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Bugfixes and improvements to selftests. On top of this, Mauro converted the

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KVM documentation to rst format, which was very welcome.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull KVM fixes from Paolo Bonzini:
 "Bugfixes and improvements to selftests.

  On top of this, Mauro converted the KVM documentation to rst format,
  which was very welcome"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (44 commits)
  docs: virt: guest-halt-polling.txt convert to ReST
  docs: kvm: review-checklist.txt: rename to ReST
  docs: kvm: Convert timekeeping.txt to ReST format
  docs: kvm: Convert s390-diag.txt to ReST format
  docs: kvm: Convert ppc-pv.txt to ReST format
  docs: kvm: Convert nested-vmx.txt to ReST format
  docs: kvm: Convert mmu.txt to ReST format
  docs: kvm: Convert locking.txt to ReST format
  docs: kvm: Convert hypercalls.txt to ReST format
  docs: kvm: arm/psci.txt: convert to ReST
  docs: kvm: convert arm/hyp-abi.txt to ReST
  docs: kvm: Convert api.txt to ReST format
  docs: kvm: convert devices/xive.txt to ReST
  docs: kvm: convert devices/xics.txt to ReST
  docs: kvm: convert devices/vm.txt to ReST
  docs: kvm: convert devices/vfio.txt to ReST
  docs: kvm: convert devices/vcpu.txt to ReST
  docs: kvm: convert devices/s390_flic.txt to ReST
  docs: kvm: convert devices/mpic.txt to ReST
  docs: kvm: convert devices/arm-vgit.txt to ReST
  ...
This commit is contained in:
Linus Torvalds 2020-02-16 13:01:42 -08:00
commit 44024adb4a
49 changed files with 4903 additions and 3364 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
Documentation/virtual/guest-halt-polling.txt → Documentation/virt/guest-halt-polling.rst
View File

@ -1,9 +1,11 @@
==================
Guest halt polling
==================
The cpuidle_haltpoll driver, with the haltpoll governor, allows
the guest vcpus to poll for a specified amount of time before
halting.
This provides the following benefits to host side polling:
1) The POLL flag is set while polling is performed, which allows
@ -29,18 +31,21 @@ Module Parameters
The haltpoll governor has 5 tunable module parameters:
1) guest_halt_poll_ns:
Maximum amount of time, in nanoseconds, that polling is
performed before halting.
Default: 200000
2) guest_halt_poll_shrink:
Division factor used to shrink per-cpu guest_halt_poll_ns when
wakeup event occurs after the global guest_halt_poll_ns.
Default: 2
3) guest_halt_poll_grow:
Multiplication factor used to grow per-cpu guest_halt_poll_ns
when event occurs after per-cpu guest_halt_poll_ns
but before global guest_halt_poll_ns.
@ -48,6 +53,7 @@ but before global guest_halt_poll_ns.
Default: 2
4) guest_halt_poll_grow_start:
The per-cpu guest_halt_poll_ns eventually reaches zero
in case of an idle system. This value sets the initial
per-cpu guest_halt_poll_ns when growing. This can
@ -66,7 +72,7 @@ high once achieves global guest_halt_poll_ns value).
Default: Y
The module parameters can be set from the debugfs files in:
The module parameters can be set from the debugfs files in::
/sys/module/haltpoll/parameters/
@ -74,5 +80,5 @@ Further Notes
=============
- Care should be taken when setting the guest_halt_poll_ns parameter as a
large value has the potential to drive the cpu usage to 100% on a machine which
would be almost entirely idle otherwise.
large value has the potential to drive the cpu usage to 100% on a machine
which would be almost entirely idle otherwise.

2
Documentation/virt/index.rst
View File

@ -8,7 +8,9 @@ Linux Virtualization Support
:maxdepth: 2
kvm/index
uml/user_mode_linux
paravirt_ops
guest-halt-polling
.. only:: html and subproject

2714
Documentation/virt/kvm/api.txt → Documentation/virt/kvm/api.rst
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File diff suppressed because it is too large Load Diff

18
Documentation/virt/kvm/arm/hyp-abi.txt → Documentation/virt/kvm/arm/hyp-abi.rst
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@ -1,4 +1,8 @@
* Internal ABI between the kernel and HYP
.. SPDX-License-Identifier: GPL-2.0
=======================================
Internal ABI between the kernel and HYP
=======================================
This file documents the interaction between the Linux kernel and the
hypervisor layer when running Linux as a hypervisor (for example
@ -19,7 +23,9 @@ and only act on individual CPUs.
Unless specified otherwise, any built-in hypervisor must implement
these functions (see arch/arm{,64}/include/asm/virt.h):
* r0/x0 = HVC_SET_VECTORS
* ::
r0/x0 = HVC_SET_VECTORS
r1/x1 = vectors
Set HVBAR/VBAR_EL2 to 'vectors' to enable a hypervisor. 'vectors'
@ -27,13 +33,17 @@ these functions (see arch/arm{,64}/include/asm/virt.h):
of the architecture. Only implemented by the initial stubs, not by
Linux hypervisors.
* r0/x0 = HVC_RESET_VECTORS
* ::
r0/x0 = HVC_RESET_VECTORS
Turn HYP/EL2 MMU off, and reset HVBAR/VBAR_EL2 to the initials
stubs' exception vector value. This effectively disables an existing
hypervisor.
* r0/x0 = HVC_SOFT_RESTART
* ::
r0/x0 = HVC_SOFT_RESTART
r1/x1 = restart address
x2 = x0's value when entering the next payload (arm64)
x3 = x1's value when entering the next payload (arm64)

12
Documentation/virt/kvm/arm/index.rst Normal file
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@ -0,0 +1,12 @@
.. SPDX-License-Identifier: GPL-2.0
===
ARM
===
.. toctree::
:maxdepth: 2
hyp-abi
psci
pvtime

36
Documentation/virt/kvm/arm/psci.txt → Documentation/virt/kvm/arm/psci.rst
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@ -1,3 +1,9 @@
.. SPDX-License-Identifier: GPL-2.0
=========================================
Power State Coordination Interface (PSCI)
=========================================
KVM implements the PSCI (Power State Coordination Interface)
specification in order to provide services such as CPU on/off, reset
and power-off to the guest.
@ -33,29 +39,39 @@ The following register is defined:
Holds the state of the firmware support to mitigate CVE-2017-5715, as
offered by KVM to the guest via a HVC call. The workaround is described
under SMCCC_ARCH_WORKAROUND_1 in [1].
Accepted values are:
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL: KVM does not offer
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL:
KVM does not offer
firmware support for the workaround. The mitigation status for the
guest is unknown.
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_AVAIL: The workaround HVC call is
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_AVAIL:
The workaround HVC call is
available to the guest and required for the mitigation.
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_REQUIRED: The workaround HVC call
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_REQUIRED:
The workaround HVC call
is available to the guest, but it is not needed on this VCPU.
* KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
Holds the state of the firmware support to mitigate CVE-2018-3639, as
offered by KVM to the guest via a HVC call. The workaround is described
under SMCCC_ARCH_WORKAROUND_2 in [1].
under SMCCC_ARCH_WORKAROUND_2 in [1]_.
Accepted values are:
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL: A workaround is not
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL:
A workaround is not
available. KVM does not offer firmware support for the workaround.
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_UNKNOWN: The workaround state is
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_UNKNOWN:
The workaround state is
unknown. KVM does not offer firmware support for the workaround.
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL: The workaround is available,
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL:
The workaround is available,
and can be disabled by a vCPU. If
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED is set, it is active for
this vCPU.
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED: The workaround is
always active on this vCPU or it is not needed.
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED:
The workaround is always active on this vCPU or it is not needed.
[1] https://developer.arm.com/-/media/developer/pdf/ARM_DEN_0070A_Firmware_interfaces_for_mitigating_CVE-2017-5715.pdf
.. [1] https://developer.arm.com/-/media/developer/pdf/ARM_DEN_0070A_Firmware_interfaces_for_mitigating_CVE-2017-5715.pdf

72
Documentation/virt/kvm/devices/arm-vgic-its.txt → Documentation/virt/kvm/devices/arm-vgic-its.rst
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@ -1,3 +1,6 @@
.. SPDX-License-Identifier: GPL-2.0
===============================================
ARM Virtual Interrupt Translation Service (ITS)
===============================================
@ -12,22 +15,32 @@ There can be multiple ITS controllers per guest, each of them has to have
a separate, non-overlapping MMIO region.
Groups:
Groups
======
KVM_DEV_ARM_VGIC_GRP_ADDR
-------------------------
Attributes:
KVM_VGIC_ITS_ADDR_TYPE (rw, 64-bit)
Base address in the guest physical address space of the GICv3 ITS
control register frame.
This address needs to be 64K aligned and the region covers 128K.
Errors:
-E2BIG: Address outside of addressable IPA range
-EINVAL: Incorrectly aligned address
-EEXIST: Address already configured
-EFAULT: Invalid user pointer for attr->addr.
-ENODEV: Incorrect attribute or the ITS is not supported.
======= =================================================
-E2BIG Address outside of addressable IPA range
-EINVAL Incorrectly aligned address
-EEXIST Address already configured
-EFAULT Invalid user pointer for attr->addr.
-ENODEV Incorrect attribute or the ITS is not supported.
======= =================================================
KVM_DEV_ARM_VGIC_GRP_CTRL
-------------------------
Attributes:
KVM_DEV_ARM_VGIC_CTRL_INIT
request the initialization of the ITS, no additional parameter in
@ -58,16 +71,21 @@ Groups:
"ITS Restore Sequence".
Errors:
-ENXIO: ITS not properly configured as required prior to setting
======= ==========================================================
-ENXIO ITS not properly configured as required prior to setting
this attribute
-ENOMEM: Memory shortage when allocating ITS internal data
-EINVAL: Inconsistent restored data
-EFAULT: Invalid guest ram access
-EBUSY: One or more VCPUS are running
-EACCES: The virtual ITS is backed by a physical GICv4 ITS, and the
-ENOMEM Memory shortage when allocating ITS internal data
-EINVAL Inconsistent restored data
-EFAULT Invalid guest ram access
-EBUSY One or more VCPUS are running
-EACCES The virtual ITS is backed by a physical GICv4 ITS, and the
state is not available
======= ==========================================================
KVM_DEV_ARM_VGIC_GRP_ITS_REGS
-----------------------------
Attributes:
The attr field of kvm_device_attr encodes the offset of the
ITS register, relative to the ITS control frame base address
@ -78,6 +96,7 @@ Groups:
be accessed with full length.
Writes to read-only registers are ignored by the kernel except for:
- GITS_CREADR. It must be restored otherwise commands in the queue
will be re-executed after restoring CWRITER. GITS_CREADR must be
restored before restoring the GITS_CTLR which is likely to enable the
@ -91,23 +110,29 @@ Groups:
For other registers, getting or setting a register has the same
effect as reading/writing the register on real hardware.
Errors:
-ENXIO: Offset does not correspond to any supported register
-EFAULT: Invalid user pointer for attr->addr
-EINVAL: Offset is not 64-bit aligned
-EBUSY: one or more VCPUS are running
======= ====================================================
-ENXIO Offset does not correspond to any supported register
-EFAULT Invalid user pointer for attr->addr
-EINVAL Offset is not 64-bit aligned
-EBUSY one or more VCPUS are running
======= ====================================================
ITS Restore Sequence:
-------------------------
---------------------
The following ordering must be followed when restoring the GIC and the ITS:
a) restore all guest memory and create vcpus
b) restore all redistributors
c) provide the ITS base address
(KVM_DEV_ARM_VGIC_GRP_ADDR)
d) restore the ITS in the following order:
1. Restore GITS_CBASER
2. Restore all other GITS_ registers, except GITS_CTLR!
2. Restore all other ``GITS_`` registers, except GITS_CTLR!
3. Load the ITS table data (KVM_DEV_ARM_ITS_RESTORE_TABLES)
4. Restore GITS_CTLR
@ -125,12 +150,13 @@ Then vcpus can be started.
entries in the collection are listed in no particular order.
All entries are 8 bytes.
Device Table Entry (DTE):
Device Table Entry (DTE)::
bits: | 63| 62 ... 49 | 48 ... 5 | 4 ... 0 |
values: | V | next | ITT_addr | Size |
where;
where:
- V indicates whether the entry is valid. If not, other fields
are not meaningful.
- next: equals to 0 if this entry is the last one; otherwise it
@ -140,24 +166,26 @@ Then vcpus can be started.
- Size specifies the supported number of bits for the EventID,
minus one
Collection Table Entry (CTE):
Collection Table Entry (CTE)::
bits: | 63| 62 .. 52 | 51 ... 16 | 15 ... 0 |
values: | V | RES0 | RDBase | ICID |
where:
- V indicates whether the entry is valid. If not, other fields are
not meaningful.
- RES0: reserved field with Should-Be-Zero-or-Preserved behavior.
- RDBase is the PE number (GICR_TYPER.Processor_Number semantic),
- ICID is the collection ID
Interrupt Translation Entry (ITE):
Interrupt Translation Entry (ITE)::
bits: | 63 ... 48 | 47 ... 16 | 15 ... 0 |
values: | next | pINTID | ICID |
where:
- next: equals to 0 if this entry is the last one; otherwise it corresponds
to the EventID offset to the next ITE capped by 2^16 -1.
- pINTID is the physical LPI ID; if zero, it means the entry is not valid

102
Documentation/virt/kvm/devices/arm-vgic-v3.txt → Documentation/virt/kvm/devices/arm-vgic-v3.rst
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@ -1,9 +1,12 @@
.. SPDX-License-Identifier: GPL-2.0
==============================================================
ARM Virtual Generic Interrupt Controller v3 and later (VGICv3)
==============================================================
Device types supported:
KVM_DEV_TYPE_ARM_VGIC_V3 ARM Generic Interrupt Controller v3.0
- KVM_DEV_TYPE_ARM_VGIC_V3 ARM Generic Interrupt Controller v3.0
Only one VGIC instance may be instantiated through this API. The created VGIC
will act as the VM interrupt controller, requiring emulated user-space devices
@ -16,6 +19,7 @@ Creating a guest GICv3 device requires a host GICv3 as well.
Groups:
KVM_DEV_ARM_VGIC_GRP_ADDR
Attributes:
KVM_VGIC_V3_ADDR_TYPE_DIST (rw, 64-bit)
Base address in the guest physical address space of the GICv3 distributor
register mappings. Only valid for KVM_DEV_TYPE_ARM_VGIC_V3.
@ -29,21 +33,25 @@ Groups:
This address needs to be 64K aligned.
KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION (rw, 64-bit)
The attribute data pointed to by kvm_device_attr.addr is a __u64 value:
The attribute data pointed to by kvm_device_attr.addr is a __u64 value::
bits: | 63 .... 52 | 51 .... 16 | 15 - 12 |11 - 0
values: | count | base | flags | index
- index encodes the unique redistributor region index
- flags: reserved for future use, currently 0
- base field encodes bits [51:16] of the guest physical base address
of the first redistributor in the region.
- count encodes the number of redistributors in the region. Must be
greater than 0.
There are two 64K pages for each redistributor in the region and
redistributors are laid out contiguously within the region. Regions
are filled with redistributors in the index order. The sum of all
region count fields must be greater than or equal to the number of
VCPUs. Redistributor regions must be registered in the incremental
index order, starting from index 0.
The characteristics of a specific redistributor region can be read
by presetting the index field in the attr data.
Only valid for KVM_DEV_TYPE_ARM_VGIC_V3.
@ -52,21 +60,25 @@ Groups:
KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION attributes.
Errors:
-E2BIG: Address outside of addressable IPA range
-EINVAL: Incorrectly aligned address, bad redistributor region
======= =============================================================
-E2BIG Address outside of addressable IPA range
-EINVAL Incorrectly aligned address, bad redistributor region
count/index, mixed redistributor region attribute usage
-EEXIST: Address already configured
-ENOENT: Attempt to read the characteristics of a non existing
-EEXIST Address already configured
-ENOENT Attempt to read the characteristics of a non existing
redistributor region
-ENXIO: The group or attribute is unknown/unsupported for this device
-ENXIO The group or attribute is unknown/unsupported for this device
or hardware support is missing.
-EFAULT: Invalid user pointer for attr->addr.
-EFAULT Invalid user pointer for attr->addr.
======= =============================================================
KVM_DEV_ARM_VGIC_GRP_DIST_REGS
KVM_DEV_ARM_VGIC_GRP_REDIST_REGS
KVM_DEV_ARM_VGIC_GRP_DIST_REGS, KVM_DEV_ARM_VGIC_GRP_REDIST_REGS
Attributes:
The attr field of kvm_device_attr encodes two values:
The attr field of kvm_device_attr encodes two values::
bits: | 63 .... 32 | 31 .... 0 |
values: | mpidr | offset |
@ -93,7 +105,8 @@ Groups:
redistributor is accessed. The mpidr is ignored for the distributor.
The mpidr encoding is based on the affinity information in the
architecture defined MPIDR, and the field is encoded as follows:
architecture defined MPIDR, and the field is encoded as follows::
| 63 .... 56 | 55 .... 48 | 47 .... 40 | 39 .... 32 |
| Aff3 | Aff2 | Aff1 | Aff0 |
@ -148,24 +161,30 @@ Groups:
ignored.
Errors:
-ENXIO: Getting or setting this register is not yet supported
-EBUSY: One or more VCPUs are running
====== =====================================================
-ENXIO Getting or setting this register is not yet supported
-EBUSY One or more VCPUs are running
====== =====================================================
KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS
Attributes:
The attr field of kvm_device_attr encodes two values:
The attr field of kvm_device_attr encodes two values::
bits: | 63 .... 32 | 31 .... 16 | 15 .... 0 |
values: | mpidr | RES | instr |
The mpidr field encodes the CPU ID based on the affinity information in the
architecture defined MPIDR, and the field is encoded as follows:
architecture defined MPIDR, and the field is encoded as follows::
| 63 .... 56 | 55 .... 48 | 47 .... 40 | 39 .... 32 |
| Aff3 | Aff2 | Aff1 | Aff0 |
The instr field encodes the system register to access based on the fields
defined in the A64 instruction set encoding for system register access
(RES means the bits are reserved for future use and should be zero):
(RES means the bits are reserved for future use and should be zero)::
| 15 ... 14 | 13 ... 11 | 10 ... 7 | 6 ... 3 | 2 ... 0 |
| Op 0 | Op1 | CRn | CRm | Op2 |
@ -178,26 +197,35 @@ Groups:
CPU interface registers access is not implemented for AArch32 mode.
Error -ENXIO is returned when accessed in AArch32 mode.
Errors:
-ENXIO: Getting or setting this register is not yet supported
-EBUSY: VCPU is running
-EINVAL: Invalid mpidr or register value supplied
======= =====================================================
-ENXIO Getting or setting this register is not yet supported
-EBUSY VCPU is running
-EINVAL Invalid mpidr or register value supplied
======= =====================================================
KVM_DEV_ARM_VGIC_GRP_NR_IRQS
Attributes:
A value describing the number of interrupts (SGI, PPI and SPI) for
this GIC instance, ranging from 64 to 1024, in increments of 32.
kvm_device_attr.addr points to a __u32 value.
Errors:
-EINVAL: Value set is out of the expected range
-EBUSY: Value has already be set.
======= ======================================
-EINVAL Value set is out of the expected range
-EBUSY Value has already be set.
======= ======================================
KVM_DEV_ARM_VGIC_GRP_CTRL
Attributes:
KVM_DEV_ARM_VGIC_CTRL_INIT
request the initialization of the VGIC, no additional parameter in
kvm_device_attr.addr.
@ -205,18 +233,24 @@ Groups:
save all LPI pending bits into guest RAM pending tables.
The first kB of the pending table is not altered by this operation.
Errors:
-ENXIO: VGIC not properly configured as required prior to calling
======= ========================================================
-ENXIO VGIC not properly configured as required prior to calling
this attribute
-ENODEV: no online VCPU
-ENOMEM: memory shortage when allocating vgic internal data
-EFAULT: Invalid guest ram access
-EBUSY: One or more VCPUS are running
-ENODEV no online VCPU
-ENOMEM memory shortage when allocating vgic internal data
-EFAULT Invalid guest ram access
-EBUSY One or more VCPUS are running
======= ========================================================
KVM_DEV_ARM_VGIC_GRP_LEVEL_INFO
Attributes:
The attr field of kvm_device_attr encodes the following values:
The attr field of kvm_device_attr encodes the following values::
bits: | 63 .... 32 | 31 .... 10 | 9 .... 0 |
values: | mpidr | info | vINTID |
@ -228,6 +262,7 @@ Groups:
VGIC_LEVEL_INFO_LINE_LEVEL:
Get/Set the input level of the IRQ line for a set of 32 contiguously
numbered interrupts.
vINTID must be a multiple of 32.
kvm_device_attr.addr points to a __u32 value which will contain a
@ -243,9 +278,14 @@ Groups:
reported with the same value regardless of the mpidr specified.
The mpidr field encodes the CPU ID based on the affinity information in the
architecture defined MPIDR, and the field is encoded as follows:
architecture defined MPIDR, and the field is encoded as follows::
| 63 .... 56 | 55 .... 48 | 47 .... 40 | 39 .... 32 |
| Aff3 | Aff2 | Aff1 | Aff0 |
Errors:
-EINVAL: vINTID is not multiple of 32 or
info field is not VGIC_LEVEL_INFO_LINE_LEVEL
======= =============================================
-EINVAL vINTID is not multiple of 32 or info field is
not VGIC_LEVEL_INFO_LINE_LEVEL
======= =============================================

67
Documentation/virt/kvm/devices/arm-vgic.txt → Documentation/virt/kvm/devices/arm-vgic.rst
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@ -1,8 +1,12 @@
.. SPDX-License-Identifier: GPL-2.0
==================================================
ARM Virtual Generic Interrupt Controller v2 (VGIC)
==================================================
Device types supported:
KVM_DEV_TYPE_ARM_VGIC_V2 ARM Generic Interrupt Controller v2.0
- KVM_DEV_TYPE_ARM_VGIC_V2 ARM Generic Interrupt Controller v2.0
Only one VGIC instance may be instantiated through either this API or the
legacy KVM_CREATE_IRQCHIP API. The created VGIC will act as the VM interrupt
@ -18,6 +22,7 @@ create both a GICv3 and GICv2 device on the same VM.
Groups:
KVM_DEV_ARM_VGIC_GRP_ADDR
Attributes:
KVM_VGIC_V2_ADDR_TYPE_DIST (rw, 64-bit)
Base address in the guest physical address space of the GIC distributor
register mappings. Only valid for KVM_DEV_TYPE_ARM_VGIC_V2.
@ -27,17 +32,23 @@ Groups:
Base address in the guest physical address space of the GIC virtual cpu
interface register mappings. Only valid for KVM_DEV_TYPE_ARM_VGIC_V2.
This address needs to be 4K aligned and the region covers 4 KByte.
Errors:
-E2BIG: Address outside of addressable IPA range
-EINVAL: Incorrectly aligned address
-EEXIST: Address already configured
-ENXIO: The group or attribute is unknown/unsupported for this device
======= =============================================================
-E2BIG Address outside of addressable IPA range
-EINVAL Incorrectly aligned address
-EEXIST Address already configured
-ENXIO The group or attribute is unknown/unsupported for this device
or hardware support is missing.
-EFAULT: Invalid user pointer for attr->addr.
-EFAULT Invalid user pointer for attr->addr.
======= =============================================================
KVM_DEV_ARM_VGIC_GRP_DIST_REGS
Attributes:
The attr field of kvm_device_attr encodes two values:
The attr field of kvm_device_attr encodes two values::
bits: | 63 .... 40 | 39 .. 32 | 31 .... 0 |
values: | reserved | vcpu_index | offset |
@ -58,14 +69,20 @@ Groups:
KVM_DEV_ARM_VGIC_GRP_DIST_REGS and KVM_DEV_ARM_VGIC_GRP_CPU_REGS) to ensure
the expected behavior. Unless GICD_IIDR has been set from userspace, writes
to the interrupt group registers (GICD_IGROUPR) are ignored.
Errors:
-ENXIO: Getting or setting this register is not yet supported
-EBUSY: One or more VCPUs are running
-EINVAL: Invalid vcpu_index supplied
======= =====================================================
-ENXIO Getting or setting this register is not yet supported
-EBUSY One or more VCPUs are running
-EINVAL Invalid vcpu_index supplied
======= =====================================================
KVM_DEV_ARM_VGIC_GRP_CPU_REGS
Attributes:
The attr field of kvm_device_attr encodes two values:
The attr field of kvm_device_attr encodes two values::
bits: | 63 .... 40 | 39 .. 32 | 31 .... 0 |
values: | reserved | vcpu_index | offset |
@ -101,27 +118,39 @@ Groups:
value left by 3 places to obtain the actual priority mask level.
Errors:
-ENXIO: Getting or setting this register is not yet supported
-EBUSY: One or more VCPUs are running
-EINVAL: Invalid vcpu_index supplied
======= =====================================================
-ENXIO Getting or setting this register is not yet supported
-EBUSY One or more VCPUs are running
-EINVAL Invalid vcpu_index supplied
======= =====================================================
KVM_DEV_ARM_VGIC_GRP_NR_IRQS
Attributes:
A value describing the number of interrupts (SGI, PPI and SPI) for
this GIC instance, ranging from 64 to 1024, in increments of 32.
Errors:
-EINVAL: Value set is out of the expected range
-EBUSY: Value has already be set, or GIC has already been initialized
======= =============================================================
-EINVAL Value set is out of the expected range
-EBUSY Value has already be set, or GIC has already been initialized
with default values.
======= =============================================================
KVM_DEV_ARM_VGIC_GRP_CTRL
Attributes:
KVM_DEV_ARM_VGIC_CTRL_INIT
request the initialization of the VGIC or ITS, no additional parameter
in kvm_device_attr.addr.
Errors:
-ENXIO: VGIC not properly configured as required prior to calling
======= =========================================================
-ENXIO VGIC not properly configured as required prior to calling
this attribute
-ENODEV: no online VCPU
-ENOMEM: memory shortage when allocating vgic internal data
-ENODEV no online VCPU
-ENOMEM memory shortage when allocating vgic internal data
======= =========================================================

19
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@ -0,0 +1,19 @@
.. SPDX-License-Identifier: GPL-2.0
=======
Devices
=======
.. toctree::
:maxdepth: 2
arm-vgic-its
arm-vgic
arm-vgic-v3
mpic
s390_flic
vcpu
vfio
vm
xics
xive

9
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@ -1,9 +1,13 @@
.. SPDX-License-Identifier: GPL-2.0
=========================
MPIC interrupt controller
=========================
Device types supported:
KVM_DEV_TYPE_FSL_MPIC_20 Freescale MPIC v2.0
KVM_DEV_TYPE_FSL_MPIC_42 Freescale MPIC v4.2
- KVM_DEV_TYPE_FSL_MPIC_20 Freescale MPIC v2.0
- KVM_DEV_TYPE_FSL_MPIC_42 Freescale MPIC v4.2
Only one MPIC instance, of any type, may be instantiated. The created
MPIC will act as the system interrupt controller, connecting to each
@ -12,6 +16,7 @@ vcpu's interrupt inputs.
Groups:
KVM_DEV_MPIC_GRP_MISC
Attributes:
KVM_DEV_MPIC_BASE_ADDR (rw, 64-bit)
Base address of the 256 KiB MPIC register space. Must be
naturally aligned. A value of zero disables the mapping.

24
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@ -1,3 +1,6 @@
.. SPDX-License-Identifier: GPL-2.0
====================================
FLIC (floating interrupt controller)
====================================
@ -31,8 +34,10 @@ Groups:
Copies all floating interrupts into a buffer provided by userspace.
When the buffer is too small it returns -ENOMEM, which is the indication
for userspace to try again with a bigger buffer.
-ENOBUFS is returned when the allocation of a kernelspace buffer has
failed.
-EFAULT is returned when copying data to userspace failed.
All interrupts remain pending, i.e. are not deleted from the list of
currently pending interrupts.
@ -60,7 +65,7 @@ Groups:
KVM_DEV_FLIC_ADAPTER_REGISTER
Register an I/O adapter interrupt source. Takes a kvm_s390_io_adapter
describing the adapter to register:
describing the adapter to register::
struct kvm_s390_io_adapter {
__u32 id;
@ -74,16 +79,19 @@ struct kvm_s390_io_adapter {
to use, maskable whether this adapter may be masked (interrupts turned off),
swap whether the indicators need to be byte swapped, and flags contains
further characteristics of the adapter.
Currently defined values for 'flags' are:
- KVM_S390_ADAPTER_SUPPRESSIBLE: adapter is subject to AIS
(adapter-interrupt-suppression) facility. This flag only has an effect if
the AIS capability is enabled.
Unknown flag values are ignored.
KVM_DEV_FLIC_ADAPTER_MODIFY
Modifies attributes of an existing I/O adapter interrupt source. Takes
a kvm_s390_io_adapter_req specifying the adapter and the operation:
a kvm_s390_io_adapter_req specifying the adapter and the operation::
struct kvm_s390_io_adapter_req {
__u32 id;
@ -103,7 +111,8 @@ struct kvm_s390_io_adapter_req {
perform a gmap translation for the guest address provided in addr,
pin a userspace page for the translated address and add it to the
list of mappings
Note: A new mapping will be created unconditionally; therefore,
.. note:: A new mapping will be created unconditionally; therefore,
the calling code should avoid making duplicate mappings.
KVM_S390_IO_ADAPTER_UNMAP
@ -112,7 +121,7 @@ struct kvm_s390_io_adapter_req {
KVM_DEV_FLIC_AISM
modify the adapter-interruption-suppression mode for a given isc if the
AIS capability is enabled. Takes a kvm_s390_ais_req describing:
AIS capability is enabled. Takes a kvm_s390_ais_req describing::
struct kvm_s390_ais_req {
__u8 isc;
@ -122,6 +131,7 @@ struct kvm_s390_ais_req {
isc contains the target I/O interruption subclass, mode the target
adapter-interruption-suppression mode. The following modes are
currently supported:
- KVM_S390_AIS_MODE_ALL: ALL-Interruptions Mode, i.e. airq injection
is always allowed;
- KVM_S390_AIS_MODE_SINGLE: SINGLE-Interruption Mode, i.e. airq
@ -139,7 +149,7 @@ struct kvm_s390_ais_req {
KVM_DEV_FLIC_AISM_ALL
Gets or sets the adapter-interruption-suppression mode for all ISCs. Takes
a kvm_s390_ais_all describing:
a kvm_s390_ais_all describing::
struct kvm_s390_ais_all {
__u8 simm; /* Single-Interruption-Mode mask */
@ -159,5 +169,5 @@ ENXIO, as specified in the API documentation). It is not possible to conclude
that a FLIC operation is unavailable based on the error code resulting from a
usage attempt.
Note: The KVM_DEV_FLIC_CLEAR_IO_IRQ ioctl will return EINVAL in case a zero
schid is specified.
.. note:: The KVM_DEV_FLIC_CLEAR_IO_IRQ ioctl will return EINVAL in case a
zero schid is specified.

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@ -0,0 +1,114 @@
.. SPDX-License-Identifier: GPL-2.0
======================
Generic vcpu interface
======================
The virtual cpu "device" also accepts the ioctls KVM_SET_DEVICE_ATTR,
KVM_GET_DEVICE_ATTR, and KVM_HAS_DEVICE_ATTR. The interface uses the same struct
kvm_device_attr as other devices, but targets VCPU-wide settings and controls.
The groups and attributes per virtual cpu, if any, are architecture specific.
1. GROUP: KVM_ARM_VCPU_PMU_V3_CTRL
==================================
:Architectures: ARM64
1.1. ATTRIBUTE: KVM_ARM_VCPU_PMU_V3_IRQ
---------------------------------------
:Parameters: in kvm_device_attr.addr the address for PMU overflow interrupt is a
pointer to an int
Returns:
======= ========================================================
-EBUSY The PMU overflow interrupt is already set
-ENXIO The overflow interrupt not set when attempting to get it
-ENODEV PMUv3 not supported
-EINVAL Invalid PMU overflow interrupt number supplied or
trying to set the IRQ number without using an in-kernel
irqchip.
======= ========================================================
A value describing the PMUv3 (Performance Monitor Unit v3) overflow interrupt
number for this vcpu. This interrupt could be a PPI or SPI, but the interrupt
type must be same for each vcpu. As a PPI, the interrupt number is the same for
all vcpus, while as an SPI it must be a separate number per vcpu.
1.2 ATTRIBUTE: KVM_ARM_VCPU_PMU_V3_INIT
---------------------------------------
:Parameters: no additional parameter in kvm_device_attr.addr
Returns:
======= ======================================================
-ENODEV PMUv3 not supported or GIC not initialized
-ENXIO PMUv3 not properly configured or in-kernel irqchip not
configured as required prior to calling this attribute
-EBUSY PMUv3 already initialized
======= ======================================================
Request the initialization of the PMUv3. If using the PMUv3 with an in-kernel
virtual GIC implementation, this must be done after initializing the in-kernel
irqchip.
2. GROUP: KVM_ARM_VCPU_TIMER_CTRL
=================================
:Architectures: ARM, ARM64
2.1. ATTRIBUTES: KVM_ARM_VCPU_TIMER_IRQ_VTIMER, KVM_ARM_VCPU_TIMER_IRQ_PTIMER
-----------------------------------------------------------------------------
:Parameters: in kvm_device_attr.addr the address for the timer interrupt is a
pointer to an int
Returns:
======= =================================
-EINVAL Invalid timer interrupt number
-EBUSY One or more VCPUs has already run
======= =================================
A value describing the architected timer interrupt number when connected to an
in-kernel virtual GIC. These must be a PPI (16 <= intid < 32). Setting the
attribute overrides the default values (see below).
============================= ==========================================
KVM_ARM_VCPU_TIMER_IRQ_VTIMER The EL1 virtual timer intid (default: 27)
KVM_ARM_VCPU_TIMER_IRQ_PTIMER The EL1 physical timer intid (default: 30)
============================= ==========================================
Setting the same PPI for different timers will prevent the VCPUs from running.
Setting the interrupt number on a VCPU configures all VCPUs created at that
time to use the number provided for a given timer, overwriting any previously
configured values on other VCPUs. Userspace should configure the interrupt
numbers on at least one VCPU after creating all VCPUs and before running any
VCPUs.
3. GROUP: KVM_ARM_VCPU_PVTIME_CTRL
==================================
:Architectures: ARM64
3.1 ATTRIBUTE: KVM_ARM_VCPU_PVTIME_IPA
--------------------------------------
:Parameters: 64-bit base address
Returns:
======= ======================================
-ENXIO Stolen time not implemented
-EEXIST Base address already set for this VCPU
-EINVAL Base address not 64 byte aligned
======= ======================================
Specifies the base address of the stolen time structure for this VCPU. The
base address must be 64 byte aligned and exist within a valid guest memory
region. See Documentation/virt/kvm/arm/pvtime.txt for more information
including the layout of the stolen time structure.

76
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@ -1,76 +0,0 @@
Generic vcpu interface
====================================
The virtual cpu "device" also accepts the ioctls KVM_SET_DEVICE_ATTR,
KVM_GET_DEVICE_ATTR, and KVM_HAS_DEVICE_ATTR. The interface uses the same struct
kvm_device_attr as other devices, but targets VCPU-wide settings and controls.
The groups and attributes per virtual cpu, if any, are architecture specific.
1. GROUP: KVM_ARM_VCPU_PMU_V3_CTRL
Architectures: ARM64
1.1. ATTRIBUTE: KVM_ARM_VCPU_PMU_V3_IRQ
Parameters: in kvm_device_attr.addr the address for PMU overflow interrupt is a
pointer to an int
Returns: -EBUSY: The PMU overflow interrupt is already set
-ENXIO: The overflow interrupt not set when attempting to get it
-ENODEV: PMUv3 not supported
-EINVAL: Invalid PMU overflow interrupt number supplied or
trying to set the IRQ number without using an in-kernel
irqchip.
A value describing the PMUv3 (Performance Monitor Unit v3) overflow interrupt
number for this vcpu. This interrupt could be a PPI or SPI, but the interrupt
type must be same for each vcpu. As a PPI, the interrupt number is the same for
all vcpus, while as an SPI it must be a separate number per vcpu.
1.2 ATTRIBUTE: KVM_ARM_VCPU_PMU_V3_INIT
Parameters: no additional parameter in kvm_device_attr.addr
Returns: -ENODEV: PMUv3 not supported or GIC not initialized
-ENXIO: PMUv3 not properly configured or in-kernel irqchip not
configured as required prior to calling this attribute
-EBUSY: PMUv3 already initialized
Request the initialization of the PMUv3. If using the PMUv3 with an in-kernel
virtual GIC implementation, this must be done after initializing the in-kernel
irqchip.
2. GROUP: KVM_ARM_VCPU_TIMER_CTRL
Architectures: ARM,ARM64
2.1. ATTRIBUTE: KVM_ARM_VCPU_TIMER_IRQ_VTIMER
2.2. ATTRIBUTE: KVM_ARM_VCPU_TIMER_IRQ_PTIMER
Parameters: in kvm_device_attr.addr the address for the timer interrupt is a
pointer to an int
Returns: -EINVAL: Invalid timer interrupt number
-EBUSY: One or more VCPUs has already run
A value describing the architected timer interrupt number when connected to an
in-kernel virtual GIC. These must be a PPI (16 <= intid < 32). Setting the
attribute overrides the default values (see below).
KVM_ARM_VCPU_TIMER_IRQ_VTIMER: The EL1 virtual timer intid (default: 27)
KVM_ARM_VCPU_TIMER_IRQ_PTIMER: The EL1 physical timer intid (default: 30)
Setting the same PPI for different timers will prevent the VCPUs from running.
Setting the interrupt number on a VCPU configures all VCPUs created at that
time to use the number provided for a given timer, overwriting any previously
configured values on other VCPUs. Userspace should configure the interrupt
numbers on at least one VCPU after creating all VCPUs and before running any
VCPUs.
3. GROUP: KVM_ARM_VCPU_PVTIME_CTRL
Architectures: ARM64
3.1 ATTRIBUTE: KVM_ARM_VCPU_PVTIME_IPA
Parameters: 64-bit base address
Returns: -ENXIO: Stolen time not implemented
-EEXIST: Base address already set for this VCPU
-EINVAL: Base address not 64 byte aligned
Specifies the base address of the stolen time structure for this VCPU. The
base address must be 64 byte aligned and exist within a valid guest memory
region. See Documentation/virt/kvm/arm/pvtime.txt for more information
including the layout of the stolen time structure.

15
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@ -1,8 +1,12 @@
.. SPDX-License-Identifier: GPL-2.0
===================
VFIO virtual device
===================
Device types supported:
KVM_DEV_TYPE_VFIO
- KVM_DEV_TYPE_VFIO
Only one VFIO instance may be created per VM. The created device
tracks VFIO groups in use by the VM and features of those groups
@ -23,14 +27,15 @@ KVM_DEV_VFIO_GROUP attributes:
for the VFIO group.
KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE: attaches a guest visible TCE table
allocated by sPAPR KVM.
kvm_device_attr.addr points to a struct:
kvm_device_attr.addr points to a struct::
struct kvm_vfio_spapr_tce {
__s32 groupfd;
__s32 tablefd;
};
where
@groupfd is a file descriptor for a VFIO group;
@tablefd is a file descriptor for a TCE table allocated via
where:
- @groupfd is a file descriptor for a VFIO group;
- @tablefd is a file descriptor for a TCE table allocated via
KVM_CREATE_SPAPR_TCE.

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@ -1,5 +1,8 @@
.. SPDX-License-Identifier: GPL-2.0
====================
Generic vm interface
====================================
====================
The virtual machine "device" also accepts the ioctls KVM_SET_DEVICE_ATTR,
KVM_GET_DEVICE_ATTR, and KVM_HAS_DEVICE_ATTR. The interface uses the same
@ -10,30 +13,38 @@ The groups and attributes per virtual machine, if any, are architecture
specific.
1. GROUP: KVM_S390_VM_MEM_CTRL
Architectures: s390
==============================
:Architectures: s390
1.1. ATTRIBUTE: KVM_S390_VM_MEM_ENABLE_CMMA
Parameters: none
Returns: -EBUSY if a vcpu is already defined, otherwise 0
-------------------------------------------
:Parameters: none
:Returns: -EBUSY if a vcpu is already defined, otherwise 0
Enables Collaborative Memory Management Assist (CMMA) for the virtual machine.
1.2. ATTRIBUTE: KVM_S390_VM_MEM_CLR_CMMA
Parameters: none
Returns: -EINVAL if CMMA was not enabled
----------------------------------------
:Parameters: none
:Returns: -EINVAL if CMMA was not enabled;
0 otherwise
Clear the CMMA status for all guest pages, so any pages the guest marked
as unused are again used any may not be reclaimed by the host.
1.3. ATTRIBUTE KVM_S390_VM_MEM_LIMIT_SIZE
Parameters: in attr->addr the address for the new limit of guest memory
Returns: -EFAULT if the given address is not accessible
-EINVAL if the virtual machine is of type UCONTROL
-E2BIG if the given guest memory is to big for that machine
-EBUSY if a vcpu is already defined
-ENOMEM if not enough memory is available for a new shadow guest mapping
0 otherwise
-----------------------------------------
:Parameters: in attr->addr the address for the new limit of guest memory
:Returns: -EFAULT if the given address is not accessible;
-EINVAL if the virtual machine is of type UCONTROL;
-E2BIG if the given guest memory is to big for that machine;
-EBUSY if a vcpu is already defined;
-ENOMEM if not enough memory is available for a new shadow guest mapping;
0 otherwise.
Allows userspace to query the actual limit and set a new limit for
the maximum guest memory size. The limit will be rounded up to
@ -42,11 +53,14 @@ the number of page table levels. In the case that there is no limit we will set
the limit to KVM_S390_NO_MEM_LIMIT (U64_MAX).
2. GROUP: KVM_S390_VM_CPU_MODEL
Architectures: s390
===============================
:Architectures: s390
2.1. ATTRIBUTE: KVM_S390_VM_CPU_MACHINE (r/o)
---------------------------------------------
Allows user space to retrieve machine and kvm specific cpu related information:
Allows user space to retrieve machine and kvm specific cpu related information::
struct kvm_s390_vm_cpu_machine {
__u64 cpuid; # CPUID of host
@ -56,15 +70,16 @@ struct kvm_s390_vm_cpu_machine {
__u64 fac_list[256]; # set of cpu facilities offered by host
}
Parameters: address of buffer to store the machine related cpu data
:Parameters: address of buffer to store the machine related cpu data
of type struct kvm_s390_vm_cpu_machine*
Returns: -EFAULT if the given address is not accessible from kernel space
-ENOMEM if not enough memory is available to process the ioctl
0 in case of success
:Returns: -EFAULT if the given address is not accessible from kernel space;
-ENOMEM if not enough memory is available to process the ioctl;
0 in case of success.
2.2. ATTRIBUTE: KVM_S390_VM_CPU_PROCESSOR (r/w)
===============================================
Allows user space to retrieve or request to change cpu related information for a vcpu:
Allows user space to retrieve or request to change cpu related information for a vcpu::
struct kvm_s390_vm_cpu_processor {
__u64 cpuid; # CPUID currently (to be) used by this vcpu
@ -79,41 +94,51 @@ retrieved by means of KVM_S390_VM_CPU_MACHINE as hint for reasonable configurati
setups. Instruction interceptions triggered by additionally set facility bits that
are not handled by KVM need to by imlemented in the VM driver code.
Parameters: address of buffer to store/set the processor related cpu
:Parameters: address of buffer to store/set the processor related cpu
data of type struct kvm_s390_vm_cpu_processor*.
Returns: -EBUSY in case 1 or more vcpus are already activated (only in write case)
-EFAULT if the given address is not accessible from kernel space
-ENOMEM if not enough memory is available to process the ioctl
0 in case of success
:Returns: -EBUSY in case 1 or more vcpus are already activated (only in write case);
-EFAULT if the given address is not accessible from kernel space;
-ENOMEM if not enough memory is available to process the ioctl;
0 in case of success.
.. _KVM_S390_VM_CPU_MACHINE_FEAT:
2.3. ATTRIBUTE: KVM_S390_VM_CPU_MACHINE_FEAT (r/o)
--------------------------------------------------
Allows user space to retrieve available cpu features. A feature is available if
provided by the hardware and supported by kvm. In theory, cpu features could
even be completely emulated by kvm.
::
struct kvm_s390_vm_cpu_feat {
__u64 feat[16]; # Bitmap (1 = feature available), MSB 0 bit numbering
};
Parameters: address of a buffer to load the feature list from.
Returns: -EFAULT if the given address is not accessible from kernel space.
:Parameters: address of a buffer to load the feature list from.
:Returns: -EFAULT if the given address is not accessible from kernel space;
0 in case of success.
2.4. ATTRIBUTE: KVM_S390_VM_CPU_PROCESSOR_FEAT (r/w)
----------------------------------------------------
Allows user space to retrieve or change enabled cpu features for all VCPUs of a
VM. Features that are not available cannot be enabled.
See 2.3. for a description of the parameter struct.
See :ref:`KVM_S390_VM_CPU_MACHINE_FEAT` for
a description of the parameter struct.
Parameters: address of a buffer to store/load the feature list from.
Returns: -EFAULT if the given address is not accessible from kernel space.
-EINVAL if a cpu feature that is not available is to be enabled.
-EBUSY if at least one VCPU has already been defined.
:Parameters: address of a buffer to store/load the feature list from.
:Returns: -EFAULT if the given address is not accessible from kernel space;
-EINVAL if a cpu feature that is not available is to be enabled;
-EBUSY if at least one VCPU has already been defined;
0 in case of success.
.. _KVM_S390_VM_CPU_MACHINE_SUBFUNC:
2.5. ATTRIBUTE: KVM_S390_VM_CPU_MACHINE_SUBFUNC (r/o)
-----------------------------------------------------
Allows user space to retrieve available cpu subfunctions without any filtering
done by a set IBC. These subfunctions are indicated to the guest VCPU via
@ -126,6 +151,8 @@ contained in the returned struct. If the affected instruction
indicates subfunctions via a "test bit" mechanism, the subfunction codes are
contained in the returned struct in MSB 0 bit numbering.
::
struct kvm_s390_vm_cpu_subfunc {
u8 plo[32]; # always valid (ESA/390 feature)
u8 ptff[16]; # valid with TOD-clock steering
@ -145,11 +172,12 @@ struct kvm_s390_vm_cpu_subfunc {
u8 reserved[1792]; # reserved for future instructions
};
Parameters: address of a buffer to load the subfunction blocks from.
Returns: -EFAULT if the given address is not accessible from kernel space.
:Parameters: address of a buffer to load the subfunction blocks from.
:Returns: -EFAULT if the given address is not accessible from kernel space;
0 in case of success.
2.6. ATTRIBUTE: KVM_S390_VM_CPU_PROCESSOR_SUBFUNC (r/w)
-------------------------------------------------------
Allows user space to retrieve or change cpu subfunctions to be indicated for
all VCPUs of a VM. This attribute will only be available if kernel and
@ -164,107 +192,125 @@ As long as no data has been written, a read will fail. The IBC will be used
to determine available subfunctions in this case, this will guarantee backward
compatibility.
See 2.5. for a description of the parameter struct.
See :ref:`KVM_S390_VM_CPU_MACHINE_SUBFUNC` for a
description of the parameter struct.
Parameters: address of a buffer to store/load the subfunction blocks from.
Returns: -EFAULT if the given address is not accessible from kernel space.
-EINVAL when reading, if there was no write yet.
-EBUSY if at least one VCPU has already been defined.
:Parameters: address of a buffer to store/load the subfunction blocks from.
:Returns: -EFAULT if the given address is not accessible from kernel space;
-EINVAL when reading, if there was no write yet;
-EBUSY if at least one VCPU has already been defined;
0 in case of success.
3. GROUP: KVM_S390_VM_TOD
Architectures: s390
=========================
:Architectures: s390
3.1. ATTRIBUTE: KVM_S390_VM_TOD_HIGH
------------------------------------
Allows user space to set/get the TOD clock extension (u8) (superseded by
KVM_S390_VM_TOD_EXT).
Parameters: address of a buffer in user space to store the data (u8) to
Returns: -EFAULT if the given address is not accessible from kernel space
:Parameters: address of a buffer in user space to store the data (u8) to
:Returns: -EFAULT if the given address is not accessible from kernel space;
-EINVAL if setting the TOD clock extension to != 0 is not supported
3.2. ATTRIBUTE: KVM_S390_VM_TOD_LOW
-----------------------------------
Allows user space to set/get bits 0-63 of the TOD clock register as defined in
the POP (u64).
Parameters: address of a buffer in user space to store the data (u64) to
Returns: -EFAULT if the given address is not accessible from kernel space
:Parameters: address of a buffer in user space to store the data (u64) to
:Returns: -EFAULT if the given address is not accessible from kernel space
3.3. ATTRIBUTE: KVM_S390_VM_TOD_EXT
-----------------------------------
Allows user space to set/get bits 0-63 of the TOD clock register as defined in
the POP (u64). If the guest CPU model supports the TOD clock extension (u8), it
also allows user space to get/set it. If the guest CPU model does not support
it, it is stored as 0 and not allowed to be set to a value != 0.
Parameters: address of a buffer in user space to store the data
:Parameters: address of a buffer in user space to store the data
(kvm_s390_vm_tod_clock) to
Returns: -EFAULT if the given address is not accessible from kernel space
:Returns: -EFAULT if the given address is not accessible from kernel space;
-EINVAL if setting the TOD clock extension to != 0 is not supported
4. GROUP: KVM_S390_VM_CRYPTO
Architectures: s390
============================
:Architectures: s390
4.1. ATTRIBUTE: KVM_S390_VM_CRYPTO_ENABLE_AES_KW (w/o)
------------------------------------------------------
Allows user space to enable aes key wrapping, including generating a new
wrapping key.
Parameters: none
Returns: 0
:Parameters: none
:Returns: 0
4.2. ATTRIBUTE: KVM_S390_VM_CRYPTO_ENABLE_DEA_KW (w/o)
------------------------------------------------------
Allows user space to enable dea key wrapping, including generating a new
wrapping key.
Parameters: none
Returns: 0
:Parameters: none
:Returns: 0
4.3. ATTRIBUTE: KVM_S390_VM_CRYPTO_DISABLE_AES_KW (w/o)
-------------------------------------------------------
Allows user space to disable aes key wrapping, clearing the wrapping key.
Parameters: none
Returns: 0
:Parameters: none
:Returns: 0
4.4. ATTRIBUTE: KVM_S390_VM_CRYPTO_DISABLE_DEA_KW (w/o)
-------------------------------------------------------
Allows user space to disable dea key wrapping, clearing the wrapping key.
Parameters: none
Returns: 0
:Parameters: none
:Returns: 0
5. GROUP: KVM_S390_VM_MIGRATION
Architectures: s390
===============================
:Architectures: s390
5.1. ATTRIBUTE: KVM_S390_VM_MIGRATION_STOP (w/o)
------------------------------------------------
Allows userspace to stop migration mode, needed for PGSTE migration.
Setting this attribute when migration mode is not active will have no
effects.
Parameters: none
Returns: 0
:Parameters: none
:Returns: 0
5.2. ATTRIBUTE: KVM_S390_VM_MIGRATION_START (w/o)
-------------------------------------------------
Allows userspace to start migration mode, needed for PGSTE migration.
Setting this attribute when migration mode is already active will have
no effects.
Parameters: none
Returns: -ENOMEM if there is not enough free memory to start migration mode
-EINVAL if the state of the VM is invalid (e.g. no memory defined)
:Parameters: none
:Returns: -ENOMEM if there is not enough free memory to start migration mode;
-EINVAL if the state of the VM is invalid (e.g. no memory defined);
0 in case of success.
5.3. ATTRIBUTE: KVM_S390_VM_MIGRATION_STATUS (r/o)
--------------------------------------------------
Allows userspace to query the status of migration mode.
Parameters: address of a buffer in user space to store the data (u64) to;
:Parameters: address of a buffer in user space to store the data (u64) to;
the data itself is either 0 if migration mode is disabled or 1
if it is enabled
Returns: -EFAULT if the given address is not accessible from kernel space
:Returns: -EFAULT if the given address is not accessible from kernel space;
0 in case of success.

24
Documentation/virt/kvm/devices/xics.txt → Documentation/virt/kvm/devices/xics.rst
View File

@ -1,20 +1,31 @@
.. SPDX-License-Identifier: GPL-2.0
=========================
XICS interrupt controller
=========================
Device type supported: KVM_DEV_TYPE_XICS
Groups:
1. KVM_DEV_XICS_GRP_SOURCES
Attributes: One per interrupt source, indexed by the source number.
Attributes:
One per interrupt source, indexed by the source number.
2. KVM_DEV_XICS_GRP_CTRL
Attributes:
2.1 KVM_DEV_XICS_NR_SERVERS (write only)
The kvm_device_attr.addr points to a __u32 value which is the number of
interrupt server numbers (ie, highest possible vcpu id plus one).
Errors:
-EINVAL: Value greater than KVM_MAX_VCPU_ID.
-EFAULT: Invalid user pointer for attr->addr.
-EBUSY: A vcpu is already connected to the device.
======= ==========================================
-EINVAL Value greater than KVM_MAX_VCPU_ID.
-EFAULT Invalid user pointer for attr->addr.
-EBUSY A vcpu is already connected to the device.
======= ==========================================
This device emulates the XICS (eXternal Interrupt Controller
Specification) defined in PAPR. The XICS has a set of interrupt
@ -53,24 +64,29 @@ the interrupt source number. The 64 bit state word has the following
bitfields, starting from the least-significant end of the word:
* Destination (server number), 32 bits
This specifies where the interrupt should be sent, and is the
interrupt server number specified for the destination vcpu.
* Priority, 8 bits
This is the priority specified for this interrupt source, where 0 is
the highest priority and 255 is the lowest. An interrupt with a
priority of 255 will never be delivered.
* Level sensitive flag, 1 bit
This bit is 1 for a level-sensitive interrupt source, or 0 for
edge-sensitive (or MSI).
* Masked flag, 1 bit
This bit is set to 1 if the interrupt is masked (cannot be delivered
regardless of its priority), for example by the ibm,int-off RTAS
call, or 0 if it is not masked.
* Pending flag, 1 bit
This bit is 1 if the source has a pending interrupt, otherwise 0.
Only one XICS instance may be created per VM.

102
Documentation/virt/kvm/devices/xive.txt → Documentation/virt/kvm/devices/xive.rst
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@ -1,8 +1,11 @@
.. SPDX-License-Identifier: GPL-2.0
===========================================================
POWER9 eXternal Interrupt Virtualization Engine (XIVE Gen1)
==========================================================
===========================================================
Device types supported:
KVM_DEV_TYPE_XIVE POWER9 XIVE Interrupt Controller generation 1
- KVM_DEV_TYPE_XIVE POWER9 XIVE Interrupt Controller generation 1
This device acts as a VM interrupt controller. It provides the KVM
interface to configure the interrupt sources of a VM in the underlying
@ -66,70 +69,98 @@ the legacy interrupt mode, referred as XICS (POWER7/8).
1. KVM_DEV_XIVE_GRP_CTRL
Provides global controls on the device
Attributes:
1.1 KVM_DEV_XIVE_RESET (write only)
Resets the interrupt controller configuration for sources and event
queues. To be used by kexec and kdump.
Errors: none
1.2 KVM_DEV_XIVE_EQ_SYNC (write only)
Sync all the sources and queues and mark the EQ pages dirty. This
to make sure that a consistent memory state is captured when
migrating the VM.
Errors: none
1.3 KVM_DEV_XIVE_NR_SERVERS (write only)
The kvm_device_attr.addr points to a __u32 value which is the number of
interrupt server numbers (ie, highest possible vcpu id plus one).
Errors:
-EINVAL: Value greater than KVM_MAX_VCPU_ID.
-EFAULT: Invalid user pointer for attr->addr.
-EBUSY: A vCPU is already connected to the device.
======= ==========================================
-EINVAL Value greater than KVM_MAX_VCPU_ID.
-EFAULT Invalid user pointer for attr->addr.
-EBUSY A vCPU is already connected to the device.
======= ==========================================
2. KVM_DEV_XIVE_GRP_SOURCE (write only)
Initializes a new source in the XIVE device and mask it.
Attributes:
Interrupt source number (64-bit)
The kvm_device_attr.addr points to a __u64 value:
The kvm_device_attr.addr points to a __u64 value::
bits: | 63 .... 2 | 1 | 0
values: | unused | level | type
- type: 0:MSI 1:LSI
- level: assertion level in case of an LSI.
Errors:
-E2BIG: Interrupt source number is out of range
-ENOMEM: Could not create a new source block
-EFAULT: Invalid user pointer for attr->addr.
-ENXIO: Could not allocate underlying HW interrupt
======= ==========================================
-E2BIG Interrupt source number is out of range
-ENOMEM Could not create a new source block
-EFAULT Invalid user pointer for attr->addr.
-ENXIO Could not allocate underlying HW interrupt
======= ==========================================
3. KVM_DEV_XIVE_GRP_SOURCE_CONFIG (write only)
Configures source targeting
Attributes:
Interrupt source number (64-bit)
The kvm_device_attr.addr points to a __u64 value:
The kvm_device_attr.addr points to a __u64 value::
bits: | 63 .... 33 | 32 | 31 .. 3 | 2 .. 0
values: | eisn | mask | server | priority
- priority: 0-7 interrupt priority level
- server: CPU number chosen to handle the interrupt
- mask: mask flag (unused)
- eisn: Effective Interrupt Source Number
Errors:
-ENOENT: Unknown source number
-EINVAL: Not initialized source number
-EINVAL: Invalid priority
-EINVAL: Invalid CPU number.
-EFAULT: Invalid user pointer for attr->addr.
-ENXIO: CPU event queues not configured or configuration of the
======= =======================================================
-ENOENT Unknown source number
-EINVAL Not initialized source number
-EINVAL Invalid priority
-EINVAL Invalid CPU number.
-EFAULT Invalid user pointer for attr->addr.
-ENXIO CPU event queues not configured or configuration of the
underlying HW interrupt failed
-EBUSY: No CPU available to serve interrupt
-EBUSY No CPU available to serve interrupt
======= =======================================================
4. KVM_DEV_XIVE_GRP_EQ_CONFIG (read-write)
Configures an event queue of a CPU
Attributes:
EQ descriptor identifier (64-bit)
The EQ descriptor identifier is a tuple (server, priority) :
The EQ descriptor identifier is a tuple (server, priority)::
bits: | 63 .... 32 | 31 .. 3 | 2 .. 0
values: | unused | server | priority
The kvm_device_attr.addr points to :
The kvm_device_attr.addr points to::
struct kvm_ppc_xive_eq {
__u32 flags;
__u32 qshift;
@ -138,6 +169,7 @@ the legacy interrupt mode, referred as XICS (POWER7/8).
__u32 qindex;
__u8 pad[40];
};
- flags: queue flags
KVM_XIVE_EQ_ALWAYS_NOTIFY (required)
forces notification without using the coalescing mechanism
@ -147,22 +179,31 @@ the legacy interrupt mode, referred as XICS (POWER7/8).
- qtoggle: current queue toggle bit
- qindex: current queue index
- pad: reserved for future use
Errors:
-ENOENT: Invalid CPU number
-EINVAL: Invalid priority
-EINVAL: Invalid flags
-EINVAL: Invalid queue size
-EINVAL: Invalid queue address
-EFAULT: Invalid user pointer for attr->addr.
-EIO: Configuration of the underlying HW failed
======= =========================================
-ENOENT Invalid CPU number
-EINVAL Invalid priority
-EINVAL Invalid flags
-EINVAL Invalid queue size
-EINVAL Invalid queue address
-EFAULT Invalid user pointer for attr->addr.
-EIO Configuration of the underlying HW failed
======= =========================================
5. KVM_DEV_XIVE_GRP_SOURCE_SYNC (write only)
Synchronize the source to flush event notifications
Attributes:
Interrupt source number (64-bit)
Errors:
-ENOENT: Unknown source number
-EINVAL: Not initialized source number
======= =============================
-ENOENT Unknown source number
-EINVAL Not initialized source number
======= =============================
* VCPU state
@ -175,7 +216,8 @@ the legacy interrupt mode, referred as XICS (POWER7/8).
as it synthesizes the priorities of the pending interrupts. We
capture a bit more to report debug information.
KVM_REG_PPC_VP_STATE (2 * 64bits)
KVM_REG_PPC_VP_STATE (2 * 64bits)::
bits: | 63 .... 32 | 31 .... 0 |
values: | TIMA word0 | TIMA word1 |
bits: | 127 .......... 64 |

86
Documentation/virt/kvm/halt-polling.txt → Documentation/virt/kvm/halt-polling.rst
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@ -1,3 +1,6 @@
.. SPDX-License-Identifier: GPL-2.0
===========================
The KVM halt polling system
===========================
@ -68,7 +71,8 @@ steady state polling interval but will only really do a good job for wakeups
which come at an approximately constant rate, otherwise there will be constant
adjustment of the polling interval.
[0] total block time: the time between when the halt polling function is
[0] total block time:
the time between when the halt polling function is
invoked and a wakeup source received (irrespective of
whether the scheduler is invoked within that function).
@ -81,31 +85,32 @@ shrunk. These variables are defined in include/linux/kvm_host.h and as module
parameters in virt/kvm/kvm_main.c, or arch/powerpc/kvm/book3s_hv.c in the
powerpc kvm-hv case.
Module Parameter | Description | Default Value
--------------------------------------------------------------------------------
halt_poll_ns | The global max polling | KVM_HALT_POLL_NS_DEFAULT
| interval which defines |
| the ceiling value of the |
| polling interval for | (per arch value)
| each vcpu. |
--------------------------------------------------------------------------------
halt_poll_ns_grow | The value by which the | 2
| halt polling interval is |
| multiplied in the |
| grow_halt_poll_ns() |
| function. |
--------------------------------------------------------------------------------
halt_poll_ns_grow_start | The initial value to grow | 10000
| to from zero in the |
| grow_halt_poll_ns() |
| function. |
--------------------------------------------------------------------------------
halt_poll_ns_shrink | The value by which the | 0
| halt polling interval is |
| divided in the |
| shrink_halt_poll_ns() |
| function. |
--------------------------------------------------------------------------------
+-----------------------+---------------------------+-------------------------+
|Module Parameter | Description | Default Value |
+-----------------------+---------------------------+-------------------------+
|halt_poll_ns | The global max polling | KVM_HALT_POLL_NS_DEFAULT|
| | interval which defines | |
| | the ceiling value of the | |
| | polling interval for | (per arch value) |
| | each vcpu. | |
+-----------------------+---------------------------+-------------------------+
|halt_poll_ns_grow | The value by which the | 2 |
| | halt polling interval is | |
| | multiplied in the | |
| | grow_halt_poll_ns() | |
| | function. | |
+-----------------------+---------------------------+-------------------------+
|halt_poll_ns_grow_start| The initial value to grow | 10000 |
| | to from zero in the | |
| | grow_halt_poll_ns() | |
| | function. | |
+-----------------------+---------------------------+-------------------------+
|halt_poll_ns_shrink | The value by which the | 0 |
| | halt polling interval is | |
| | divided in the | |
| | shrink_halt_poll_ns() | |
| | function. | |
+-----------------------+---------------------------+-------------------------+
These module parameters can be set from the debugfs files in:
@ -117,20 +122,19 @@ Note: that these module parameters are system wide values and are not able to
Further Notes
=============
- Care should be taken when setting the halt_poll_ns module parameter as a
large value has the potential to drive the cpu usage to 100% on a machine which
would be almost entirely idle otherwise. This is because even if a guest has
wakeups during which very little work is done and which are quite far apart, if
the period is shorter than the global max polling interval (halt_poll_ns) then
the host will always poll for the entire block time and thus cpu utilisation
will go to 100%.
- Care should be taken when setting the halt_poll_ns module parameter as a large value
has the potential to drive the cpu usage to 100% on a machine which would be almost
entirely idle otherwise. This is because even if a guest has wakeups during which very
little work is done and which are quite far apart, if the period is shorter than the
global max polling interval (halt_poll_ns) then the host will always poll for the
entire block time and thus cpu utilisation will go to 100%.
- Halt polling essentially presents a trade off between power usage and latency
and the module parameters should be used to tune the affinity for this. Idle
cpu time is essentially converted to host kernel time with the aim of decreasing
latency when entering the guest.
- Halt polling essentially presents a trade off between power usage and latency and
the module parameters should be used to tune the affinity for this. Idle cpu time is
essentially converted to host kernel time with the aim of decreasing latency when
entering the guest.
- Halt polling will only be conducted by the host when no other tasks are
runnable on that cpu, otherwise the polling will cease immediately and
schedule will be invoked to allow that other task to run. Thus this doesn't
allow a guest to denial of service the cpu.
- Halt polling will only be conducted by the host when no other tasks are runnable on
that cpu, otherwise the polling will cease immediately and schedule will be invoked to
allow that other task to run. Thus this doesn't allow a guest to denial of service the
cpu.

105
Documentation/virt/kvm/hypercalls.txt → Documentation/virt/kvm/hypercalls.rst
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@ -1,5 +1,9 @@
Linux KVM Hypercall:
.. SPDX-License-Identifier: GPL-2.0
===================
Linux KVM Hypercall
===================
X86:
KVM Hypercalls have a three-byte sequence of either the vmcall or the vmmcall
instruction. The hypervisor can replace it with instructions that are
@ -34,7 +38,8 @@ MIPS:
the return value is placed in $2 (v0).
KVM Hypercalls Documentation
===========================
============================
The template for each hypercall is:
1. Hypercall name.
2. Architecture(s)
@ -43,42 +48,49 @@ The template for each hypercall is:
1. KVM_HC_VAPIC_POLL_IRQ
------------------------
Architecture: x86
Status: active
Purpose: Trigger guest exit so that the host can check for pending
:Architecture: x86
:Status: active
:Purpose: Trigger guest exit so that the host can check for pending
interrupts on reentry.
2. KVM_HC_MMU_OP
------------------------
Architecture: x86
Status: deprecated.
Purpose: Support MMU operations such as writing to PTE,
----------------
:Architecture: x86
:Status: deprecated.
:Purpose: Support MMU operations such as writing to PTE,
flushing TLB, release PT.
3. KVM_HC_FEATURES
------------------------
Architecture: PPC
Status: active
Purpose: Expose hypercall availability to the guest. On x86 platforms, cpuid
used to enumerate which hypercalls are available. On PPC, either device tree
based lookup ( which is also what EPAPR dictates) OR KVM specific enumeration
mechanism (which is this hypercall) can be used.
------------------
:Architecture: PPC
:Status: active
:Purpose: Expose hypercall availability to the guest. On x86 platforms, cpuid
used to enumerate which hypercalls are available. On PPC, either
device tree based lookup ( which is also what EPAPR dictates)
OR KVM specific enumeration mechanism (which is this hypercall)
can be used.
4. KVM_HC_PPC_MAP_MAGIC_PAGE
------------------------
Architecture: PPC
Status: active
Purpose: To enable communication between the hypervisor and guest there is a
----------------------------
:Architecture: PPC
:Status: active
:Purpose: To enable communication between the hypervisor and guest there is a
shared page that contains parts of supervisor visible register state.
The guest can map this shared page to access its supervisor register through
memory using this hypercall.
The guest can map this shared page to access its supervisor register
through memory using this hypercall.
5. KVM_HC_KICK_CPU
------------------------
Architecture: x86
Status: active
Purpose: Hypercall used to wakeup a vcpu from HLT state
Usage example : A vcpu of a paravirtualized guest that is busywaiting in guest
------------------
:Architecture: x86
:Status: active
:Purpose: Hypercall used to wakeup a vcpu from HLT state
:Usage example:
A vcpu of a paravirtualized guest that is busywaiting in guest
kernel mode for an event to occur (ex: a spinlock to become available) can
execute HLT instruction once it has busy-waited for more than a threshold
time-interval. Execution of HLT instruction would cause the hypervisor to put
@ -89,10 +101,11 @@ is used in the hypercall for future use.
6. KVM_HC_CLOCK_PAIRING
------------------------
Architecture: x86
Status: active
Purpose: Hypercall used to synchronize host and guest clocks.
-----------------------
:Architecture: x86
:Status: active
:Purpose: Hypercall used to synchronize host and guest clocks.
Usage:
a0: guest physical address where host copies
@ -101,6 +114,8 @@ a0: guest physical address where host copies
a1: clock_type, ATM only KVM_CLOCK_PAIRING_WALLCLOCK (0)
is supported (corresponding to the host's CLOCK_REALTIME clock).
::
struct kvm_clock_pairing {
__s64 sec;
__s64 nsec;
@ -123,15 +138,16 @@ Returns KVM_EOPNOTSUPP if the host does not use TSC clocksource,
or if clock type is different than KVM_CLOCK_PAIRING_WALLCLOCK.
6. KVM_HC_SEND_IPI
------------------------
Architecture: x86
Status: active
Purpose: Send IPIs to multiple vCPUs.
------------------
a0: lower part of the bitmap of destination APIC IDs
a1: higher part of the bitmap of destination APIC IDs
a2: the lowest APIC ID in bitmap
a3: APIC ICR
:Architecture: x86
:Status: active
:Purpose: Send IPIs to multiple vCPUs.
- a0: lower part of the bitmap of destination APIC IDs
- a1: higher part of the bitmap of destination APIC IDs
- a2: the lowest APIC ID in bitmap
- a3: APIC ICR
The hypercall lets a guest send multicast IPIs, with at most 128
128 destinations per hypercall in 64-bit mode and 64 vCPUs per
@ -143,12 +159,13 @@ corresponds to the APIC ID a2+1, and so on.
Returns the number of CPUs to which the IPIs were delivered successfully.
7. KVM_HC_SCHED_YIELD
------------------------
Architecture: x86
Status: active
Purpose: Hypercall used to yield if the IPI target vCPU is preempted
---------------------
:Architecture: x86
:Status: active
:Purpose: Hypercall used to yield if the IPI target vCPU is preempted
a0: destination APIC ID
Usage example: When sending a call-function IPI-many to vCPUs, yield if
:Usage example: When sending a call-function IPI-many to vCPUs, yield if
any of the IPI target vCPUs was preempted.

16
Documentation/virt/kvm/index.rst
View File

@ -7,6 +7,22 @@ KVM
.. toctree::
:maxdepth: 2
api
amd-memory-encryption
cpuid
halt-polling
hypercalls
locking
mmu
msr
nested-vmx
ppc-pv
s390-diag
timekeeping
vcpu-requests
review-checklist
arm/index
devices/index

243
Documentation/virt/kvm/locking.rst Normal file
View File

@ -0,0 +1,243 @@
.. SPDX-License-Identifier: GPL-2.0
=================
KVM Lock Overview
=================
1. Acquisition Orders
---------------------
The acquisition orders for mutexes are as follows:
- kvm->lock is taken outside vcpu->mutex
- kvm->lock is taken outside kvm->slots_lock and kvm->irq_lock
- kvm->slots_lock is taken outside kvm->irq_lock, though acquiring
them together is quite rare.
On x86, vcpu->mutex is taken outside kvm->arch.hyperv.hv_lock.
Everything else is a leaf: no other lock is taken inside the critical
sections.
2. Exception
------------
Fast page fault:
Fast page fault is the fast path which fixes the guest page fault out of
the mmu-lock on x86. Currently, the page fault can be fast in one of the
following two cases:
1. Access Tracking: The SPTE is not present, but it is marked for access
tracking i.e. the SPTE_SPECIAL_MASK is set. That means we need to
restore the saved R/X bits. This is described in more detail later below.
2. Write-Protection: The SPTE is present and the fault is
caused by write-protect. That means we just need to change the W bit of
the spte.
What we use to avoid all the race is the SPTE_HOST_WRITEABLE bit and
SPTE_MMU_WRITEABLE bit on the spte:
- SPTE_HOST_WRITEABLE means the gfn is writable on host.
- SPTE_MMU_WRITEABLE means the gfn is writable on mmu. The bit is set when
the gfn is writable on guest mmu and it is not write-protected by shadow
page write-protection.
On fast page fault path, we will use cmpxchg to atomically set the spte W
bit if spte.SPTE_HOST_WRITEABLE = 1 and spte.SPTE_WRITE_PROTECT = 1, or
restore the saved R/X bits if VMX_EPT_TRACK_ACCESS mask is set, or both. This
is safe because whenever changing these bits can be detected by cmpxchg.
But we need carefully check these cases:
1) The mapping from gfn to pfn
The mapping from gfn to pfn may be changed since we can only ensure the pfn
is not changed during cmpxchg. This is a ABA problem, for example, below case
will happen:
+------------------------------------------------------------------------+
| At the beginning:: |
| |
| gpte = gfn1 |
| gfn1 is mapped to pfn1 on host |
| spte is the shadow page table entry corresponding with gpte and |
| spte = pfn1 |
+------------------------------------------------------------------------+
| On fast page fault path: |
+------------------------------------+-----------------------------------+
| CPU 0: | CPU 1: |
+------------------------------------+-----------------------------------+
| :: | |
| | |
| old_spte = *spte; | |
+------------------------------------+-----------------------------------+
| | pfn1 is swapped out:: |
| | |
| | spte = 0; |
| | |
| | pfn1 is re-alloced for gfn2. |
| | |
| | gpte is changed to point to |
| | gfn2 by the guest:: |
| | |
| | spte = pfn1; |
+------------------------------------+-----------------------------------+
| :: |
| |
| if (cmpxchg(spte, old_spte, old_spte+W) |
| mark_page_dirty(vcpu->kvm, gfn1) |
| OOPS!!! |
+------------------------------------------------------------------------+
We dirty-log for gfn1, that means gfn2 is lost in dirty-bitmap.
For direct sp, we can easily avoid it since the spte of direct sp is fixed
to gfn. For indirect sp, before we do cmpxchg, we call gfn_to_pfn_atomic()
to pin gfn to pfn, because after gfn_to_pfn_atomic():
- We have held the refcount of pfn that means the pfn can not be freed and
be reused for another gfn.
- The pfn is writable that means it can not be shared between different gfns
by KSM.
Then, we can ensure the dirty bitmaps is correctly set for a gfn.
Currently, to simplify the whole things, we disable fast page fault for
indirect shadow page.
2) Dirty bit tracking
In the origin code, the spte can be fast updated (non-atomically) if the
spte is read-only and the Accessed bit has already been set since the
Accessed bit and Dirty bit can not be lost.
But it is not true after fast page fault since the spte can be marked
writable between reading spte and updating spte. Like below case:
+------------------------------------------------------------------------+
| At the beginning:: |
| |
| spte.W = 0 |
| spte.Accessed = 1 |
+------------------------------------+-----------------------------------+
| CPU 0: | CPU 1: |
+------------------------------------+-----------------------------------+
| In mmu_spte_clear_track_bits():: | |
| | |
| old_spte = *spte; | |
| | |
| | |
| /* 'if' condition is satisfied. */| |
| if (old_spte.Accessed == 1 && | |
| old_spte.W == 0) | |
| spte = 0ull; | |
+------------------------------------+-----------------------------------+
| | on fast page fault path:: |
| | |
| | spte.W = 1 |
| | |
| | memory write on the spte:: |
| | |
| | spte.Dirty = 1 |
+------------------------------------+-----------------------------------+
| :: | |
| | |
| else | |
| old_spte = xchg(spte, 0ull) | |
| if (old_spte.Accessed == 1) | |
| kvm_set_pfn_accessed(spte.pfn);| |
| if (old_spte.Dirty == 1) | |
| kvm_set_pfn_dirty(spte.pfn); | |
| OOPS!!! | |
+------------------------------------+-----------------------------------+
The Dirty bit is lost in this case.
In order to avoid this kind of issue, we always treat the spte as "volatile"
if it can be updated out of mmu-lock, see spte_has_volatile_bits(), it means,
the spte is always atomically updated in this case.
3) flush tlbs due to spte updated
If the spte is updated from writable to readonly, we should flush all TLBs,
otherwise rmap_write_protect will find a read-only spte, even though the
writable spte might be cached on a CPU's TLB.
As mentioned before, the spte can be updated to writable out of mmu-lock on
fast page fault path, in order to easily audit the path, we see if TLBs need
be flushed caused by this reason in mmu_spte_update() since this is a common
function to update spte (present -> present).
Since the spte is "volatile" if it can be updated out of mmu-lock, we always
atomically update the spte, the race caused by fast page fault can be avoided,
See the comments in spte_has_volatile_bits() and mmu_spte_update().
Lockless Access Tracking:
This is used for Intel CPUs that are using EPT but do not support the EPT A/D
bits. In this case, when the KVM MMU notifier is called to track accesses to a
page (via kvm_mmu_notifier_clear_flush_young), it marks the PTE as not-present
by clearing the RWX bits in the PTE and storing the original R & X bits in
some unused/ignored bits. In addition, the SPTE_SPECIAL_MASK is also set on the
PTE (using the ignored bit 62). When the VM tries to access the page later on,
a fault is generated and the fast page fault mechanism described above is used
to atomically restore the PTE to a Present state. The W bit is not saved when
the PTE is marked for access tracking and during restoration to the Present
state, the W bit is set depending on whether or not it was a write access. If
it wasn't, then the W bit will remain clear until a write access happens, at
which time it will be set using the Dirty tracking mechanism described above.
3. Reference
------------
:Name: kvm_lock
:Type: mutex
:Arch: any
:Protects: - vm_list
:Name: kvm_count_lock
:Type: raw_spinlock_t
:Arch: any
:Protects: - hardware virtualization enable/disable
:Comment: 'raw' because hardware enabling/disabling must be atomic /wrt
migration.
:Name: kvm_arch::tsc_write_lock
:Type: raw_spinlock
:Arch: x86
:Protects: - kvm_arch::{last_tsc_write,last_tsc_nsec,last_tsc_offset}
- tsc offset in vmcb
:Comment: 'raw' because updating the tsc offsets must not be preempted.
:Name: kvm->mmu_lock
:Type: spinlock_t
:Arch: any
:Protects: -shadow page/shadow tlb entry
:Comment: it is a spinlock since it is used in mmu notifier.
:Name: kvm->srcu
:Type: srcu lock
:Arch: any
:Protects: - kvm->memslots
- kvm->buses
:Comment: The srcu read lock must be held while accessing memslots (e.g.
when using gfn_to_* functions) and while accessing in-kernel
MMIO/PIO address->device structure mapping (kvm->buses).
The srcu index can be stored in kvm_vcpu->srcu_idx per vcpu
if it is needed by multiple functions.
:Name: blocked_vcpu_on_cpu_lock
:Type: spinlock_t
:Arch: x86
:Protects: blocked_vcpu_on_cpu
:Comment: This is a per-CPU lock and it is used for VT-d posted-interrupts.
When VT-d posted-interrupts is supported and the VM has assigned
devices, we put the blocked vCPU on the list blocked_vcpu_on_cpu
protected by blocked_vcpu_on_cpu_lock, when VT-d hardware issues
wakeup notification event since external interrupts from the
assigned devices happens, we will find the vCPU on the list to
wakeup.

215
Documentation/virt/kvm/locking.txt
View File

@ -1,215 +0,0 @@
KVM Lock Overview
=================
1. Acquisition Orders
---------------------
The acquisition orders for mutexes are as follows:
- kvm->lock is taken outside vcpu->mutex
- kvm->lock is taken outside kvm->slots_lock and kvm->irq_lock
- kvm->slots_lock is taken outside kvm->irq_lock, though acquiring
them together is quite rare.
On x86, vcpu->mutex is taken outside kvm->arch.hyperv.hv_lock.
Everything else is a leaf: no other lock is taken inside the critical
sections.
2: Exception
------------
Fast page fault:
Fast page fault is the fast path which fixes the guest page fault out of
the mmu-lock on x86. Currently, the page fault can be fast in one of the
following two cases:
1. Access Tracking: The SPTE is not present, but it is marked for access
tracking i.e. the SPTE_SPECIAL_MASK is set. That means we need to
restore the saved R/X bits. This is described in more detail later below.
2. Write-Protection: The SPTE is present and the fault is
caused by write-protect. That means we just need to change the W bit of the
spte.
What we use to avoid all the race is the SPTE_HOST_WRITEABLE bit and
SPTE_MMU_WRITEABLE bit on the spte:
- SPTE_HOST_WRITEABLE means the gfn is writable on host.
- SPTE_MMU_WRITEABLE means the gfn is writable on mmu. The bit is set when
the gfn is writable on guest mmu and it is not write-protected by shadow
page write-protection.
On fast page fault path, we will use cmpxchg to atomically set the spte W
bit if spte.SPTE_HOST_WRITEABLE = 1 and spte.SPTE_WRITE_PROTECT = 1, or
restore the saved R/X bits if VMX_EPT_TRACK_ACCESS mask is set, or both. This
is safe because whenever changing these bits can be detected by cmpxchg.
But we need carefully check these cases:
1): The mapping from gfn to pfn
The mapping from gfn to pfn may be changed since we can only ensure the pfn
is not changed during cmpxchg. This is a ABA problem, for example, below case
will happen:
At the beginning:
gpte = gfn1
gfn1 is mapped to pfn1 on host
spte is the shadow page table entry corresponding with gpte and
spte = pfn1
VCPU 0 VCPU0
on fast page fault path:
old_spte = *spte;
pfn1 is swapped out:
spte = 0;
pfn1 is re-alloced for gfn2.
gpte is changed to point to
gfn2 by the guest:
spte = pfn1;
if (cmpxchg(spte, old_spte, old_spte+W)
mark_page_dirty(vcpu->kvm, gfn1)
OOPS!!!
We dirty-log for gfn1, that means gfn2 is lost in dirty-bitmap.
For direct sp, we can easily avoid it since the spte of direct sp is fixed
to gfn. For indirect sp, before we do cmpxchg, we call gfn_to_pfn_atomic()
to pin gfn to pfn, because after gfn_to_pfn_atomic():
- We have held the refcount of pfn that means the pfn can not be freed and
be reused for another gfn.
- The pfn is writable that means it can not be shared between different gfns
by KSM.
Then, we can ensure the dirty bitmaps is correctly set for a gfn.
Currently, to simplify the whole things, we disable fast page fault for
indirect shadow page.
2): Dirty bit tracking
In the origin code, the spte can be fast updated (non-atomically) if the
spte is read-only and the Accessed bit has already been set since the
Accessed bit and Dirty bit can not be lost.
But it is not true after fast page fault since the spte can be marked
writable between reading spte and updating spte. Like below case:
At the beginning:
spte.W = 0
spte.Accessed = 1
VCPU 0 VCPU0
In mmu_spte_clear_track_bits():
old_spte = *spte;
/* 'if' condition is satisfied. */
if (old_spte.Accessed == 1 &&
old_spte.W == 0)
spte = 0ull;
on fast page fault path:
spte.W = 1
memory write on the spte:
spte.Dirty = 1
else
old_spte = xchg(spte, 0ull)
if (old_spte.Accessed == 1)
kvm_set_pfn_accessed(spte.pfn);
if (old_spte.Dirty == 1)
kvm_set_pfn_dirty(spte.pfn);
OOPS!!!
The Dirty bit is lost in this case.
In order to avoid this kind of issue, we always treat the spte as "volatile"
if it can be updated out of mmu-lock, see spte_has_volatile_bits(), it means,
the spte is always atomically updated in this case.
3): flush tlbs due to spte updated
If the spte is updated from writable to readonly, we should flush all TLBs,
otherwise rmap_write_protect will find a read-only spte, even though the
writable spte might be cached on a CPU's TLB.
As mentioned before, the spte can be updated to writable out of mmu-lock on
fast page fault path, in order to easily audit the path, we see if TLBs need
be flushed caused by this reason in mmu_spte_update() since this is a common
function to update spte (present -> present).
Since the spte is "volatile" if it can be updated out of mmu-lock, we always
atomically update the spte, the race caused by fast page fault can be avoided,
See the comments in spte_has_volatile_bits() and mmu_spte_update().
Lockless Access Tracking:
This is used for Intel CPUs that are using EPT but do not support the EPT A/D
bits. In this case, when the KVM MMU notifier is called to track accesses to a
page (via kvm_mmu_notifier_clear_flush_young), it marks the PTE as not-present
by clearing the RWX bits in the PTE and storing the original R & X bits in
some unused/ignored bits. In addition, the SPTE_SPECIAL_MASK is also set on the
PTE (using the ignored bit 62). When the VM tries to access the page later on,
a fault is generated and the fast page fault mechanism described above is used
to atomically restore the PTE to a Present state. The W bit is not saved when
the PTE is marked for access tracking and during restoration to the Present
state, the W bit is set depending on whether or not it was a write access. If
it wasn't, then the W bit will remain clear until a write access happens, at
which time it will be set using the Dirty tracking mechanism described above.
3. Reference
------------
Name: kvm_lock
Type: mutex
Arch: any
Protects: - vm_list
Name: kvm_count_lock
Type: raw_spinlock_t
Arch: any
Protects: - hardware virtualization enable/disable
Comment: 'raw' because hardware enabling/disabling must be atomic /wrt
migration.
Name: kvm_arch::tsc_write_lock
Type: raw_spinlock
Arch: x86
Protects: - kvm_arch::{last_tsc_write,last_tsc_nsec,last_tsc_offset}
- tsc offset in vmcb
Comment: 'raw' because updating the tsc offsets must not be preempted.
Name: kvm->mmu_lock
Type: spinlock_t
Arch: any
Protects: -shadow page/shadow tlb entry
Comment: it is a spinlock since it is used in mmu notifier.
Name: kvm->srcu
Type: srcu lock
Arch: any
Protects: - kvm->memslots
- kvm->buses
Comment: The srcu read lock must be held while accessing memslots (e.g.
when using gfn_to_* functions) and while accessing in-kernel
MMIO/PIO address->device structure mapping (kvm->buses).
The srcu index can be stored in kvm_vcpu->srcu_idx per vcpu
if it is needed by multiple functions.
Name: blocked_vcpu_on_cpu_lock
Type: spinlock_t
Arch: x86
Protects: blocked_vcpu_on_cpu
Comment: This is a per-CPU lock and it is used for VT-d posted-interrupts.
When VT-d posted-interrupts is supported and the VM has assigned
devices, we put the blocked vCPU on the list blocked_vcpu_on_cpu
protected by blocked_vcpu_on_cpu_lock, when VT-d hardware issues
wakeup notification event since external interrupts from the
assigned devices happens, we will find the vCPU on the list to
wakeup.

58
Documentation/virt/kvm/mmu.txt → Documentation/virt/kvm/mmu.rst
View File

@ -1,3 +1,6 @@
.. SPDX-License-Identifier: GPL-2.0
======================
The x86 kvm shadow mmu
======================
@ -7,27 +10,37 @@ physical addresses to host physical addresses.
The mmu code attempts to satisfy the following requirements:
- correctness: the guest should not be able to determine that it is running
- correctness:
the guest should not be able to determine that it is running
on an emulated mmu except for timing (we attempt to comply
with the specification, not emulate the characteristics of
a particular implementation such as tlb size)
- security: the guest must not be able to touch host memory not assigned
- security:
the guest must not be able to touch host memory not assigned
to it
- performance: minimize the performance penalty imposed by the mmu
- scaling: need to scale to large memory and large vcpu guests
- hardware: support the full range of x86 virtualization hardware
- integration: Linux memory management code must be in control of guest memory
- performance:
minimize the performance penalty imposed by the mmu
- scaling:
need to scale to large memory and large vcpu guests
- hardware:
support the full range of x86 virtualization hardware
- integration:
Linux memory management code must be in control of guest memory
so that swapping, page migration, page merging, transparent
hugepages, and similar features work without change
- dirty tracking: report writes to guest memory to enable live migration
- dirty tracking:
report writes to guest memory to enable live migration
and framebuffer-based displays
- footprint: keep the amount of pinned kernel memory low (most memory
- footprint:
keep the amount of pinned kernel memory low (most memory
should be shrinkable)
- reliability: avoid multipage or GFP_ATOMIC allocations
- reliability:
avoid multipage or GFP_ATOMIC allocations
Acronyms
========
==== ====================================================================
pfn host page frame number
hpa host physical address
hva host virtual address
@ -41,6 +54,7 @@ pte page table entry (used also to refer generically to paging structure
gpte guest pte (referring to gfns)
spte shadow pte (referring to pfns)
tdp two dimensional paging (vendor neutral term for NPT and EPT)
==== ====================================================================
Virtual and real hardware supported
===================================
@ -90,11 +104,13 @@ Events
The mmu is driven by events, some from the guest, some from the host.
Guest generated events:
- writes to control registers (especially cr3)
- invlpg/invlpga instruction execution
- access to missing or protected translations
Host generated events:
- changes in the gpa->hpa translation (either through gpa->hva changes or
through hva->hpa changes)
- memory pressure (the shrinker)
@ -117,11 +133,14 @@ Leaf ptes point at guest pages.
The following table shows translations encoded by leaf ptes, with higher-level
translations in parentheses:
Non-nested guests:
Non-nested guests::
nonpaging: gpa->hpa
paging: gva->gpa->hpa
paging, tdp: (gva->)gpa->hpa
Nested guests:
Nested guests::
non-tdp: ngva->gpa->hpa (*)
tdp: (ngva->)ngpa->gpa->hpa
@ -291,28 +310,41 @@ Handling a page fault is performed as follows:
- if the RSV bit of the error code is set, the page fault is caused by guest
accessing MMIO and cached MMIO information is available.
- walk shadow page table
- check for valid generation number in the spte (see "Fast invalidation of
MMIO sptes" below)
- cache the information to vcpu->arch.mmio_gva, vcpu->arch.mmio_access and
vcpu->arch.mmio_gfn, and call the emulator
- If both P bit and R/W bit of error code are set, this could possibly
be handled as a "fast page fault" (fixed without taking the MMU lock). See
the description in Documentation/virt/kvm/locking.txt.
- if needed, walk the guest page tables to determine the guest translation
(gva->gpa or ngpa->gpa)
- if permissions are insufficient, reflect the fault back to the guest
- determine the host page
- if this is an mmio request, there is no host page; cache the info to
vcpu->arch.mmio_gva, vcpu->arch.mmio_access and vcpu->arch.mmio_gfn
- walk the shadow page table to find the spte for the translation,
instantiating missing intermediate page tables as necessary
- If this is an mmio request, cache the mmio info to the spte and set some
reserved bit on the spte (see callers of kvm_mmu_set_mmio_spte_mask)
- try to unsynchronize the page
- if successful, we can let the guest continue and modify the gpte
- emulate the instruction
- if failed, unshadow the page and let the guest continue
- update any translations that were modified by the instruction
invlpg handling:
@ -324,10 +356,12 @@ invlpg handling:
Guest control register updates:
- mov to cr3
- look up new shadow roots
- synchronize newly reachable shadow pages
- mov to cr0/cr4/efer
- set up mmu context for new paging mode
- look up new shadow roots
- synchronize newly reachable shadow pages
@ -358,6 +392,7 @@ on fault type:
(user write faults generate a #PF)
In the first case there are two additional complications:
- if CR4.SMEP is enabled: since we've turned the page into a kernel page,
the kernel may now execute it. We handle this by also setting spte.nx.
If we get a user fetch or read fault, we'll change spte.u=1 and
@ -446,4 +481,3 @@ Further reading
- NPT presentation from KVM Forum 2008
http://www.linux-kvm.org/images/c/c8/KvmForum2008%24kdf2008_21.pdf

135
Documentation/virt/kvm/msr.txt → Documentation/virt/kvm/msr.rst
View File

@ -1,6 +1,10 @@
KVM-specific MSRs.
Glauber Costa <glommer@redhat.com>, Red Hat Inc, 2010
=====================================================
.. SPDX-License-Identifier: GPL-2.0
=================
KVM-specific MSRs
=================
:Author: Glauber Costa <glommer@redhat.com>, Red Hat Inc, 2010
KVM makes use of some custom MSRs to service some requests.
@ -9,15 +13,17 @@ Custom MSRs have a range reserved for them, that goes from
but they are deprecated and their use is discouraged.
Custom MSR list
--------
---------------
The current supported Custom MSR list is:
MSR_KVM_WALL_CLOCK_NEW: 0x4b564d00
MSR_KVM_WALL_CLOCK_NEW:
0x4b564d00
data: 4-byte alignment physical address of a memory area which must be
data:
4-byte alignment physical address of a memory area which must be
in guest RAM. This memory is expected to hold a copy of the following
structure:
structure::
struct pvclock_wall_clock {
u32 version;
@ -30,13 +36,16 @@ MSR_KVM_WALL_CLOCK_NEW: 0x4b564d00
Users that want to reliably query this information more than once have
to write more than once to this MSR. Fields have the following meanings:
version: guest has to check version before and after grabbing
version:
guest has to check version before and after grabbing
time information and check that they are both equal and even.
An odd version indicates an in-progress update.
sec: number of seconds for wallclock at time of boot.
sec:
number of seconds for wallclock at time of boot.
nsec: number of nanoseconds for wallclock at time of boot.
nsec:
number of nanoseconds for wallclock at time of boot.
In order to get the current wallclock time, the system_time from
MSR_KVM_SYSTEM_TIME_NEW needs to be added.
@ -47,11 +56,13 @@ MSR_KVM_WALL_CLOCK_NEW: 0x4b564d00
Availability of this MSR must be checked via bit 3 in 0x4000001 cpuid
leaf prior to usage.
MSR_KVM_SYSTEM_TIME_NEW: 0x4b564d01
MSR_KVM_SYSTEM_TIME_NEW:
0x4b564d01
data: 4-byte aligned physical address of a memory area which must be in
data:
4-byte aligned physical address of a memory area which must be in
guest RAM, plus an enable bit in bit 0. This memory is expected to hold
a copy of the following structure:
a copy of the following structure::
struct pvclock_vcpu_time_info {
u32 version;
@ -72,23 +83,28 @@ MSR_KVM_SYSTEM_TIME_NEW: 0x4b564d01
Fields have the following meanings:
version: guest has to check version before and after grabbing
version:
guest has to check version before and after grabbing
time information and check that they are both equal and even.
An odd version indicates an in-progress update.
tsc_timestamp: the tsc value at the current VCPU at the time
tsc_timestamp:
the tsc value at the current VCPU at the time
of the update of this structure. Guests can subtract this value
from current tsc to derive a notion of elapsed time since the
structure update.
system_time: a host notion of monotonic time, including sleep
system_time:
a host notion of monotonic time, including sleep
time at the time this structure was last updated. Unit is
nanoseconds.
tsc_to_system_mul: multiplier to be used when converting
tsc_to_system_mul:
multiplier to be used when converting
tsc-related quantity to nanoseconds
tsc_shift: shift to be used when converting tsc-related
tsc_shift:
shift to be used when converting tsc-related
quantity to nanoseconds. This shift will ensure that
multiplication with tsc_to_system_mul does not overflow.
A positive value denotes a left shift, a negative value
@ -96,7 +112,7 @@ MSR_KVM_SYSTEM_TIME_NEW: 0x4b564d01
The conversion from tsc to nanoseconds involves an additional
right shift by 32 bits. With this information, guests can
derive per-CPU time by doing:
derive per-CPU time by doing::
time = (current_tsc - tsc_timestamp)
if (tsc_shift >= 0)
@ -106,29 +122,34 @@ MSR_KVM_SYSTEM_TIME_NEW: 0x4b564d01
time = (time * tsc_to_system_mul) >> 32
time = time + system_time
flags: bits in this field indicate extended capabilities
flags:
bits in this field indicate extended capabilities
coordinated between the guest and the hypervisor. Availability
of specific flags has to be checked in 0x40000001 cpuid leaf.
Current flags are:
flag bit | cpuid bit | meaning
-------------------------------------------------------------
| | time measures taken across
0 | 24 | multiple cpus are guaranteed to
| | be monotonic
-------------------------------------------------------------
| | guest vcpu has been paused by
1 | N/A | the host
| | See 4.70 in api.txt
-------------------------------------------------------------
+-----------+--------------+----------------------------------+
| flag bit | cpuid bit | meaning |
+-----------+--------------+----------------------------------+
| | | time measures taken across |
| 0 | 24 | multiple cpus are guaranteed to |
| | | be monotonic |
+-----------+--------------+----------------------------------+
| | | guest vcpu has been paused by |
| 1 | N/A | the host |
| | | See 4.70 in api.txt |
+-----------+--------------+----------------------------------+
Availability of this MSR must be checked via bit 3 in 0x4000001 cpuid
leaf prior to usage.
MSR_KVM_WALL_CLOCK: 0x11
MSR_KVM_WALL_CLOCK:
0x11
data and functioning: same as MSR_KVM_WALL_CLOCK_NEW. Use that instead.
data and functioning:
same as MSR_KVM_WALL_CLOCK_NEW. Use that instead.
This MSR falls outside the reserved KVM range and may be removed in the
future. Its usage is deprecated.
@ -136,9 +157,11 @@ MSR_KVM_WALL_CLOCK: 0x11
Availability of this MSR must be checked via bit 0 in 0x4000001 cpuid
leaf prior to usage.
MSR_KVM_SYSTEM_TIME: 0x12
MSR_KVM_SYSTEM_TIME:
0x12
data and functioning: same as MSR_KVM_SYSTEM_TIME_NEW. Use that instead.
data and functioning:
same as MSR_KVM_SYSTEM_TIME_NEW. Use that instead.
This MSR falls outside the reserved KVM range and may be removed in the
future. Its usage is deprecated.
@ -146,7 +169,7 @@ MSR_KVM_SYSTEM_TIME: 0x12
Availability of this MSR must be checked via bit 0 in 0x4000001 cpuid
leaf prior to usage.
The suggested algorithm for detecting kvmclock presence is then:
The suggested algorithm for detecting kvmclock presence is then::
if (!kvm_para_available()) /* refer to cpuid.txt */
return NON_PRESENT;
@ -163,8 +186,11 @@ MSR_KVM_SYSTEM_TIME: 0x12
} else
return NON_PRESENT;
MSR_KVM_ASYNC_PF_EN: 0x4b564d02
data: Bits 63-6 hold 64-byte aligned physical address of a
MSR_KVM_ASYNC_PF_EN:
0x4b564d02
data:
Bits 63-6 hold 64-byte aligned physical address of a
64 byte memory area which must be in guest RAM and must be
zeroed. Bits 5-3 are reserved and should be zero. Bit 0 is 1
when asynchronous page faults are enabled on the vcpu 0 when
@ -200,11 +226,13 @@ MSR_KVM_ASYNC_PF_EN: 0x4b564d02
Currently type 2 APF will be always delivered on the same vcpu as
type 1 was, but guest should not rely on that.
MSR_KVM_STEAL_TIME: 0x4b564d03
MSR_KVM_STEAL_TIME:
0x4b564d03
data: 64-byte alignment physical address of a memory area which must be
data:
64-byte alignment physical address of a memory area which must be
in guest RAM, plus an enable bit in bit 0. This memory is expected to
hold a copy of the following structure:
hold a copy of the following structure::
struct kvm_steal_time {
__u64 steal;
@ -224,25 +252,32 @@ MSR_KVM_STEAL_TIME: 0x4b564d03
Fields have the following meanings:
version: a sequence counter. In other words, guest has to check
version:
a sequence counter. In other words, guest has to check
this field before and after grabbing time information and make
sure they are both equal and even. An odd version indicates an
in-progress update.
flags: At this point, always zero. May be used to indicate
flags:
At this point, always zero. May be used to indicate
changes in this structure in the future.
steal: the amount of time in which this vCPU did not run, in
steal:
the amount of time in which this vCPU did not run, in
nanoseconds. Time during which the vcpu is idle, will not be
reported as steal time.
preempted: indicate the vCPU who owns this struct is running or
preempted:
indicate the vCPU who owns this struct is running or
not. Non-zero values mean the vCPU has been preempted. Zero
means the vCPU is not preempted. NOTE, it is always zero if the
the hypervisor doesn't support this field.
MSR_KVM_EOI_EN: 0x4b564d04
data: Bit 0 is 1 when PV end of interrupt is enabled on the vcpu; 0
MSR_KVM_EOI_EN:
0x4b564d04
data:
Bit 0 is 1 when PV end of interrupt is enabled on the vcpu; 0
when disabled. Bit 1 is reserved and must be zero. When PV end of
interrupt is enabled (bit 0 set), bits 63-2 hold a 4-byte aligned
physical address of a 4 byte memory area which must be in guest RAM and
@ -274,11 +309,13 @@ MSR_KVM_EOI_EN: 0x4b564d04
clear it using a single CPU instruction, such as test and clear, or
compare and exchange.
MSR_KVM_POLL_CONTROL: 0x4b564d05
MSR_KVM_POLL_CONTROL:
0x4b564d05
Control host-side polling.
data: Bit 0 enables (1) or disables (0) host-side HLT polling logic.
data:
Bit 0 enables (1) or disables (0) host-side HLT polling logic.
KVM guests can request the host not to poll on HLT, for example if
they are performing polling themselves.

33
Documentation/virt/kvm/nested-vmx.txt → Documentation/virt/kvm/nested-vmx.rst
View File

@ -1,3 +1,6 @@
.. SPDX-License-Identifier: GPL-2.0
==========
Nested VMX
==========
@ -75,6 +78,8 @@ of this structure changes, this can break live migration across KVM versions.
VMCS12_REVISION (from vmx.c) should be changed if struct vmcs12 or its inner
struct shadow_vmcs is ever changed.
::
typedef u64 natural_width;
struct __packed vmcs12 {
/* According to the Intel spec, a VMCS region must start with
@ -220,21 +225,21 @@ Authors
-------
These patches were written by:
Abel Gordon, abelg <at> il.ibm.com
Nadav Har'El, nyh <at> il.ibm.com
Orit Wasserman, oritw <at> il.ibm.com
Ben-Ami Yassor, benami <at> il.ibm.com
Muli Ben-Yehuda, muli <at> il.ibm.com
- Abel Gordon, abelg <at> il.ibm.com
- Nadav Har'El, nyh <at> il.ibm.com
- Orit Wasserman, oritw <at> il.ibm.com
- Ben-Ami Yassor, benami <at> il.ibm.com
- Muli Ben-Yehuda, muli <at> il.ibm.com
With contributions by:
Anthony Liguori, aliguori <at> us.ibm.com
Mike Day, mdday <at> us.ibm.com
Michael Factor, factor <at> il.ibm.com
Zvi Dubitzky, dubi <at> il.ibm.com
- Anthony Liguori, aliguori <at> us.ibm.com
- Mike Day, mdday <at> us.ibm.com
- Michael Factor, factor <at> il.ibm.com
- Zvi Dubitzky, dubi <at> il.ibm.com
And valuable reviews by:
Avi Kivity, avi <at> redhat.com
Gleb Natapov, gleb <at> redhat.com
Marcelo Tosatti, mtosatti <at> redhat.com
Kevin Tian, kevin.tian <at> intel.com
and others.
- Avi Kivity, avi <at> redhat.com
- Gleb Natapov, gleb <at> redhat.com
- Marcelo Tosatti, mtosatti <at> redhat.com
- Kevin Tian, kevin.tian <at> intel.com
- and others.

26
Documentation/virt/kvm/ppc-pv.txt → Documentation/virt/kvm/ppc-pv.rst
View File

@ -1,3 +1,6 @@
.. SPDX-License-Identifier: GPL-2.0
=================================
The PPC KVM paravirtual interface
=================================
@ -34,8 +37,9 @@ up the hypercall. To call a hypercall, just call these instructions.
The parameters are as follows:
======== ================ ================
Register IN OUT
======== ================ ================
r0 - volatile
r3 1st parameter Return code
r4 2nd parameter 1st output value
@ -47,6 +51,7 @@ The parameters are as follows:
r10 8th parameter 7th output value
r11 hypercall number 8th output value
r12 - volatile
======== ================ ================
Hypercall definitions are shared in generic code, so the same hypercall numbers
apply for x86 and powerpc alike with the exception that each KVM hypercall
@ -54,11 +59,13 @@ also needs to be ORed with the KVM vendor code which is (42 << 16).
Return codes can be as follows:
==== =========================
Code Meaning
==== =========================
0 Success
12 Hypercall not implemented
<0 Error
==== =========================
The magic page
==============
@ -72,7 +79,7 @@ desired location. The first parameter indicates the effective address when the
MMU is enabled. The second parameter indicates the address in real mode, if
applicable to the target. For now, we always map the page to -4096. This way we
can access it using absolute load and store functions. The following
instruction reads the first field of the magic page:
instruction reads the first field of the magic page::
ld rX, -4096(0)
@ -93,8 +100,10 @@ a bitmap of available features inside the magic page.
The following enhancements to the magic page are currently available:
============================ =======================================
KVM_MAGIC_FEAT_SR Maps SR registers r/w in the magic page
KVM_MAGIC_FEAT_MAS0_TO_SPRG7 Maps MASn, ESR, PIR and high SPRGs
============================ =======================================
For enhanced features in the magic page, please check for the existence of the
feature before using them!
@ -121,8 +130,8 @@ when entering the guest or don't have any impact on the hypervisor's behavior.
The following bits are safe to be set inside the guest:
MSR_EE
MSR_RI
- MSR_EE
- MSR_RI
If any other bit changes in the MSR, please still use mtmsr(d).
@ -138,9 +147,9 @@ guest. Implementing any of those mappings is optional, as the instruction traps
also act on the shared page. So calling privileged instructions still works as
before.
======================= ================================
From To
==== ==
======================= ================================
mfmsr rX ld rX, magic_page->msr
mfsprg rX, 0 ld rX, magic_page->sprg0
mfsprg rX, 1 ld rX, magic_page->sprg1
@ -173,7 +182,7 @@ mtsrin rX, rY b <special mtsrin section>
[BookE only]
wrteei [0|1] b <special wrteei section>
======================= ================================
Some instructions require more logic to determine what's going on than a load
or store instruction can deliver. To enable patching of those, we keep some
@ -191,6 +200,7 @@ for example.
Hypercall ABIs in KVM on PowerPC
=================================
1) KVM hypercalls (ePAPR)
These are ePAPR compliant hypercall implementation (mentioned above). Even

3
Documentation/virt/kvm/review-checklist.txt → Documentation/virt/kvm/review-checklist.rst
View File

@ -1,3 +1,6 @@
.. SPDX-License-Identifier: GPL-2.0
================================
Review checklist for kvm patches
================================

5
Documentation/virt/kvm/s390-diag.txt → Documentation/virt/kvm/s390-diag.rst
View File

@ -1,3 +1,6 @@
.. SPDX-License-Identifier: GPL-2.0
=============================
The s390 DIAGNOSE call on KVM
=============================
@ -16,7 +19,7 @@ DIAGNOSE calls by the guest cause a mandatory intercept. This implies
all supported DIAGNOSE calls need to be handled by either KVM or its
userspace.
All DIAGNOSE calls supported by KVM use the RS-a format:
All DIAGNOSE calls supported by KVM use the RS-a format::
--------------------------------------
| '83' | R1 | R3 | B2 | D2 |

135
Documentation/virt/kvm/timekeeping.txt → Documentation/virt/kvm/timekeeping.rst
View File

@ -1,17 +1,21 @@
.. SPDX-License-Identifier: GPL-2.0
======================================================
Timekeeping Virtualization for X86-Based Architectures
======================================================
Zachary Amsden <zamsden@redhat.com>
Copyright (c) 2010, Red Hat. All rights reserved.
:Author: Zachary Amsden <zamsden@redhat.com>
:Copyright: (c) 2010, Red Hat. All rights reserved.
.. Contents
1) Overview
2) Timing Devices
3) TSC Hardware
4) Virtualization Problems
=========================================================================
1) Overview
1. Overview
===========
One of the most complicated parts of the X86 platform, and specifically,
the virtualization of this platform is the plethora of timing devices available
@ -27,15 +31,15 @@ The purpose of this document is to collect data and information relevant to
timekeeping which may be difficult to find elsewhere, specifically,
information relevant to KVM and hardware-based virtualization.
=========================================================================
2) Timing Devices
2. Timing Devices
=================
First we discuss the basic hardware devices available. TSC and the related
KVM clock are special enough to warrant a full exposition and are described in
the following section.
2.1) i8254 - PIT
2.1. i8254 - PIT
----------------
One of the first timer devices available is the programmable interrupt timer,
or PIT. The PIT has a fixed frequency 1.193182 MHz base clock and three
@ -50,7 +54,7 @@ The PIT uses I/O ports 0x40 - 0x43. Access to the 16-bit counters is done
using single or multiple byte access to the I/O ports. There are 6 modes
available, but not all modes are available to all timers, as only timer 2
has a connected gate input, required for modes 1 and 5. The gate line is
controlled by port 61h, bit 0, as illustrated in the following diagram.
controlled by port 61h, bit 0, as illustrated in the following diagram::
-------------- ----------------
| | | |
@ -70,29 +74,33 @@ controlled by port 61h, bit 0, as illustrated in the following diagram.
| | |
|------>| CLOCK OUT | ---------> Port 61h, bit 5
| | |
Port 61h, bit 0 ---------->| GATE TIMER 2 | \_.---- ____
Port 61h, bit 0 -------->| GATE TIMER 2 | \_.---- ____
---------------- _| )--|LPF|---Speaker
/ *---- \___/
Port 61h, bit 1 -----------------------------------/
Port 61h, bit 1 ---------------------------------/
The timer modes are now described.
Mode 0: Single Timeout. This is a one-shot software timeout that counts down
Mode 0: Single Timeout.
This is a one-shot software timeout that counts down
when the gate is high (always true for timers 0 and 1). When the count
reaches zero, the output goes high.
Mode 1: Triggered One-shot. The output is initially set high. When the gate
Mode 1: Triggered One-shot.
The output is initially set high. When the gate
line is set high, a countdown is initiated (which does not stop if the gate is
lowered), during which the output is set low. When the count reaches zero,
the output goes high.
Mode 2: Rate Generator. The output is initially set high. When the countdown
Mode 2: Rate Generator.
The output is initially set high. When the countdown
reaches 1, the output goes low for one count and then returns high. The value
is reloaded and the countdown automatically resumes. If the gate line goes
low, the count is halted. If the output is low when the gate is lowered, the
output automatically goes high (this only affects timer 2).
Mode 3: Square Wave. This generates a high / low square wave. The count
Mode 3: Square Wave.
This generates a high / low square wave. The count
determines the length of the pulse, which alternates between high and low
when zero is reached. The count only proceeds when gate is high and is
automatically reloaded on reaching zero. The count is decremented twice at
@ -103,12 +111,14 @@ Mode 3: Square Wave. This generates a high / low square wave. The count
values are not observed when reading. This is the intended mode for timer 2,
which generates sine-like tones by low-pass filtering the square wave output.
Mode 4: Software Strobe. After programming this mode and loading the counter,
Mode 4: Software Strobe.
After programming this mode and loading the counter,
the output remains high until the counter reaches zero. Then the output
goes low for 1 clock cycle and returns high. The counter is not reloaded.
Counting only occurs when gate is high.
Mode 5: Hardware Strobe. After programming and loading the counter, the
Mode 5: Hardware Strobe.
After programming and loading the counter, the
output remains high. When the gate is raised, a countdown is initiated
(which does not stop if the gate is lowered). When the counter reaches zero,
the output goes low for 1 clock cycle and then returns high. The counter is
@ -118,13 +128,13 @@ In addition to normal binary counting, the PIT supports BCD counting. The
command port, 0x43 is used to set the counter and mode for each of the three
timers.
PIT commands, issued to port 0x43, using the following bit encoding:
PIT commands, issued to port 0x43, using the following bit encoding::
Bit 7-4: Command (See table below)
Bit 3-1: Mode (000 = Mode 0, 101 = Mode 5, 11X = undefined)
Bit 0 : Binary (0) / BCD (1)
Command table:
Command table::
0000 - Latch Timer 0 count for port 0x40
sample and hold the count to be read in port 0x40;
@ -177,7 +187,8 @@ Command table:
Bit 3-1 = Mode
Bit 0 = Binary (0) / BCD mode (1)
2.2) RTC
2.2. RTC
--------
The second device which was available in the original PC was the MC146818 real
time clock. The original device is now obsolete, and usually emulated by the
@ -201,7 +212,7 @@ in progress, as indicated in the status register.
The clock uses a 32.768kHz crystal, so bits 6-4 of register A should be
programmed to a 32kHz divider if the RTC is to count seconds.
This is the RAM map originally used for the RTC/CMOS:
This is the RAM map originally used for the RTC/CMOS::
Location Size Description
------------------------------------------
@ -255,7 +266,8 @@ ODh byte Register D (read only)
32h byte Current century BCD (*)
(*) location vendor specific and now determined from ACPI global tables
2.3) APIC
2.3. APIC
---------
On Pentium and later processors, an on-board timer is available to each CPU
as part of the Advanced Programmable Interrupt Controller. The APIC is
@ -276,7 +288,8 @@ timer is programmed through the LVT (local vector timer) register, is capable
of one-shot or periodic operation, and is based on the bus clock divided down
by the programmable divider register.
2.4) HPET
2.4. HPET
---------
HPET is quite complex, and was originally intended to replace the PIT / RTC
support of the X86 PC. It remains to be seen whether that will be the case, as
@ -297,7 +310,8 @@ indicated through ACPI tables by the BIOS.
Detailed specification of the HPET is beyond the current scope of this
document, as it is also very well documented elsewhere.
2.5) Offboard Timers
2.5. Offboard Timers
--------------------
Several cards, both proprietary (watchdog boards) and commonplace (e1000) have
timing chips built into the cards which may have registers which are accessible
@ -307,9 +321,8 @@ general frowned upon as not playing by the agreed rules of the game. Such a
timer device would require additional support to be virtualized properly and is
not considered important at this time as no known operating system does this.
=========================================================================
3) TSC Hardware
3. TSC Hardware
===============
The TSC or time stamp counter is relatively simple in theory; it counts
instruction cycles issued by the processor, which can be used as a measure of
@ -340,7 +353,8 @@ allows the guest visible TSC to be offset by a constant. Newer implementations
promise to allow the TSC to additionally be scaled, but this hardware is not
yet widely available.
3.1) TSC synchronization
3.1. TSC synchronization
------------------------
The TSC is a CPU-local clock in most implementations. This means, on SMP
platforms, the TSCs of different CPUs may start at different times depending
@ -357,7 +371,8 @@ practice, getting a perfectly synchronized TSC will not be possible unless all
values are read from the same clock, which generally only is possible on single
socket systems or those with special hardware support.
3.2) TSC and CPU hotplug
3.2. TSC and CPU hotplug
------------------------
As touched on already, CPUs which arrive later than the boot time of the system
may not have a TSC value that is synchronized with the rest of the system.
@ -367,7 +382,8 @@ a guarantee. This can have the effect of bringing a system from a state where
TSC is synchronized back to a state where TSC synchronization flaws, however
small, may be exposed to the OS and any virtualization environment.
3.3) TSC and multi-socket / NUMA
3.3. TSC and multi-socket / NUMA
--------------------------------
Multi-socket systems, especially large multi-socket systems are likely to have
individual clocksources rather than a single, universally distributed clock.
@ -385,7 +401,8 @@ standards for telecommunications and computer equipment.
It is recommended not to trust the TSCs to remain synchronized on NUMA or
multiple socket systems for these reasons.
3.4) TSC and C-states
3.4. TSC and C-states
---------------------
C-states, or idling states of the processor, especially C1E and deeper sleep
states may be problematic for TSC as well. The TSC may stop advancing in such
@ -396,7 +413,8 @@ based on CPU and chipset identifications.
The TSC in such a case may be corrected by catching it up to a known external
clocksource.
3.5) TSC frequency change / P-states
3.5. TSC frequency change / P-states
------------------------------------
To make things slightly more interesting, some CPUs may change frequency. They
may or may not run the TSC at the same rate, and because the frequency change
@ -416,14 +434,16 @@ other processors. In such cases, the TSC on halted CPUs could advance faster
than that of non-halted processors. AMD Turion processors are known to have
this problem.
3.6) TSC and STPCLK / T-states
3.6. TSC and STPCLK / T-states
------------------------------
External signals given to the processor may also have the effect of stopping
the TSC. This is typically done for thermal emergency power control to prevent
an overheating condition, and typically, there is no way to detect that this
condition has happened.
3.7) TSC virtualization - VMX
3.7. TSC virtualization - VMX
-----------------------------
VMX provides conditional trapping of RDTSC, RDMSR, WRMSR and RDTSCP
instructions, which is enough for full virtualization of TSC in any manner. In
@ -431,14 +451,16 @@ addition, VMX allows passing through the host TSC plus an additional TSC_OFFSET
field specified in the VMCS. Special instructions must be used to read and
write the VMCS field.
3.8) TSC virtualization - SVM
3.8. TSC virtualization - SVM
-----------------------------
SVM provides conditional trapping of RDTSC, RDMSR, WRMSR and RDTSCP
instructions, which is enough for full virtualization of TSC in any manner. In
addition, SVM allows passing through the host TSC plus an additional offset
field specified in the SVM control block.
3.9) TSC feature bits in Linux
3.9. TSC feature bits in Linux
------------------------------
In summary, there is no way to guarantee the TSC remains in perfect
synchronization unless it is explicitly guaranteed by the architecture. Even
@ -448,13 +470,16 @@ despite being locally consistent.
The following feature bits are used by Linux to signal various TSC attributes,
but they can only be taken to be meaningful for UP or single node systems.
X86_FEATURE_TSC : The TSC is available in hardware
X86_FEATURE_RDTSCP : The RDTSCP instruction is available
X86_FEATURE_CONSTANT_TSC : The TSC rate is unchanged with P-states
X86_FEATURE_NONSTOP_TSC : The TSC does not stop in C-states
X86_FEATURE_TSC_RELIABLE : TSC sync checks are skipped (VMware)
========================= =======================================
X86_FEATURE_TSC The TSC is available in hardware
X86_FEATURE_RDTSCP The RDTSCP instruction is available
X86_FEATURE_CONSTANT_TSC The TSC rate is unchanged with P-states
X86_FEATURE_NONSTOP_TSC The TSC does not stop in C-states
X86_FEATURE_TSC_RELIABLE TSC sync checks are skipped (VMware)
========================= =======================================
4) Virtualization Problems
4. Virtualization Problems
==========================
Timekeeping is especially problematic for virtualization because a number of
challenges arise. The most obvious problem is that time is now shared between
@ -473,7 +498,8 @@ BIOS, but not in such an extreme fashion. However, the fact that SMM mode may
cause similar problems to virtualization makes it a good justification for
solving many of these problems on bare metal.
4.1) Interrupt clocking
4.1. Interrupt clocking
-----------------------
One of the most immediate problems that occurs with legacy operating systems
is that the system timekeeping routines are often designed to keep track of
@ -502,7 +528,8 @@ thus requires interrupt slewing to keep proper time. It does use a low enough
rate (ed: is it 18.2 Hz?) however that it has not yet been a problem in
practice.
4.2) TSC sampling and serialization
4.2. TSC sampling and serialization
-----------------------------------
As the highest precision time source available, the cycle counter of the CPU
has aroused much interest from developers. As explained above, this timer has
@ -524,7 +551,8 @@ it may be necessary for an implementation to guard against "backwards" reads of
the TSC as seen from other CPUs, even in an otherwise perfectly synchronized
system.
4.3) Timespec aliasing
4.3. Timespec aliasing
----------------------
Additionally, this lack of serialization from the TSC poses another challenge
when using results of the TSC when measured against another time source. As
@ -548,7 +576,8 @@ This aliasing requires care in the computation and recalibration of kvmclock
and any other values derived from TSC computation (such as TSC virtualization
itself).
4.4) Migration
4.4. Migration
--------------
Migration of a virtual machine raises problems for timekeeping in two ways.
First, the migration itself may take time, during which interrupts cannot be
@ -566,7 +595,8 @@ always be caught up to the original rate. KVM clock avoids these problems by
simply storing multipliers and offsets against the TSC for the guest to convert
back into nanosecond resolution values.
4.5) Scheduling
4.5. Scheduling
---------------
Since scheduling may be based on precise timing and firing of interrupts, the
scheduling algorithms of an operating system may be adversely affected by
@ -579,7 +609,8 @@ In an attempt to work around this, several implementations have provided a
paravirtualized scheduler clock, which reveals the true amount of CPU time for
which a virtual machine has been running.
4.6) Watchdogs
4.6. Watchdogs
--------------
Watchdog timers, such as the lock detector in Linux may fire accidentally when
running under hardware virtualization due to timer interrupts being delayed or
@ -587,7 +618,8 @@ misinterpretation of the passage of real time. Usually, these warnings are
spurious and can be ignored, but in some circumstances it may be necessary to
disable such detection.
4.7) Delays and precision timing
4.7. Delays and precision timing
--------------------------------
Precise timing and delays may not be possible in a virtualized system. This
can happen if the system is controlling physical hardware, or issues delays to
@ -600,7 +632,8 @@ The second issue may cause performance problems, but this is unlikely to be a
significant issue. In many cases these delays may be eliminated through
configuration or paravirtualization.
4.8) Covert channels and leaks
4.8. Covert channels and leaks
------------------------------
In addition to the above problems, time information will inevitably leak to the
guest about the host in anything but a perfect implementation of virtualized

1186
Documentation/virt/uml/UserModeLinux-HOWTO.txt → Documentation/virt/uml/user_mode_linux.rst
View File

File diff suppressed because it is too large Load Diff

16
arch/x86/include/asm/kvm_host.h
View File

@ -781,9 +781,19 @@ struct kvm_vcpu_arch {
u64 msr_kvm_poll_control;
/*
* Indicate whether the access faults on its page table in guest
* which is set when fix page fault and used to detect unhandeable
* instruction.
* Indicates the guest is trying to write a gfn that contains one or
* more of the PTEs used to translate the write itself, i.e. the access
* is changing its own translation in the guest page tables. KVM exits
* to userspace if emulation of the faulting instruction fails and this
* flag is set, as KVM cannot make forward progress.
*
* If emulation fails for a write to guest page tables, KVM unprotects
* (zaps) the shadow page for the target gfn and resumes the guest to
* retry the non-emulatable instruction (on hardware). Unprotecting the
* gfn doesn't allow forward progress for a self-changing access because
* doing so also zaps the translation for the gfn, i.e. retrying the
* instruction will hit a !PRESENT fault, which results in a new shadow
* page and sends KVM back to square one.
*/
bool write_fault_to_shadow_pgtable;

3
arch/x86/kvm/lapic.c
View File

@ -1080,9 +1080,6 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
result = 1;
/* assumes that there are only KVM_APIC_INIT/SIPI */
apic->pending_events = (1UL << KVM_APIC_INIT);
/* make sure pending_events is visible before sending
* the request */
smp_wmb();
kvm_make_request(KVM_REQ_EVENT, vcpu);
kvm_vcpu_kick(vcpu);
}

13
arch/x86/kvm/mmu.h
View File

@ -102,6 +102,19 @@ static inline void kvm_mmu_load_cr3(struct kvm_vcpu *vcpu)
kvm_get_active_pcid(vcpu));
}
int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
bool prefault);
static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
u32 err, bool prefault)
{
#ifdef CONFIG_RETPOLINE
if (likely(vcpu->arch.mmu->page_fault == kvm_tdp_page_fault))
return kvm_tdp_page_fault(vcpu, cr2_or_gpa, err, prefault);
#endif
return vcpu->arch.mmu->page_fault(vcpu, cr2_or_gpa, err, prefault);
}
/*
* Currently, we have two sorts of write-protection, a) the first one
* write-protects guest page to sync the guest modification, b) another one is

9
arch/x86/kvm/mmu/mmu.c
View File

@ -4219,7 +4219,7 @@ int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code,
}
EXPORT_SYMBOL_GPL(kvm_handle_page_fault);
static int tdp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
bool prefault)
{
int max_level;
@ -4925,7 +4925,7 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
return;
context->mmu_role.as_u64 = new_role.as_u64;
context->page_fault = tdp_page_fault;
context->page_fault = kvm_tdp_page_fault;
context->sync_page = nonpaging_sync_page;
context->invlpg = nonpaging_invlpg;
context->update_pte = nonpaging_update_pte;
@ -5436,9 +5436,8 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
}
if (r == RET_PF_INVALID) {
r = vcpu->arch.mmu->page_fault(vcpu, cr2_or_gpa,
lower_32_bits(error_code),
false);
r = kvm_mmu_do_page_fault(vcpu, cr2_or_gpa,
lower_32_bits(error_code), false);
WARN_ON(r == RET_PF_INVALID);
}

2
arch/x86/kvm/mmu/paging_tmpl.h
View File

@ -33,7 +33,7 @@
#define PT_GUEST_ACCESSED_SHIFT PT_ACCESSED_SHIFT
#define PT_HAVE_ACCESSED_DIRTY(mmu) true
#ifdef CONFIG_X86_64
#define PT_MAX_FULL_LEVELS 4
#define PT_MAX_FULL_LEVELS PT64_ROOT_MAX_LEVEL
#define CMPXCHG cmpxchg
#else
#define CMPXCHG cmpxchg64

2
arch/x86/kvm/svm.c
View File

@ -2175,7 +2175,6 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
u32 dummy;
u32 eax = 1;
vcpu->arch.microcode_version = 0x01000065;
svm->spec_ctrl = 0;
svm->virt_spec_ctrl = 0;
@ -2266,6 +2265,7 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
init_vmcb(svm);
svm_init_osvw(vcpu);
vcpu->arch.microcode_version = 0x01000065;
return 0;

33
arch/x86/kvm/vmx/nested.c
View File

@ -544,7 +544,8 @@ static void nested_vmx_disable_intercept_for_msr(unsigned long *msr_bitmap_l1,
}
}
static inline void enable_x2apic_msr_intercepts(unsigned long *msr_bitmap) {
static inline void enable_x2apic_msr_intercepts(unsigned long *msr_bitmap)
{
int msr;
for (msr = 0x800; msr <= 0x8ff; msr += BITS_PER_LONG) {
@ -1981,7 +1982,7 @@ static int nested_vmx_handle_enlightened_vmptrld(struct kvm_vcpu *vcpu,
}
/*
* Clean fields data can't de used on VMLAUNCH and when we switch
* Clean fields data can't be used on VMLAUNCH and when we switch
* between different L2 guests as KVM keeps a single VMCS12 per L1.
*/
if (from_launch || evmcs_gpa_changed)
@ -3575,6 +3576,33 @@ static void nested_vmx_inject_exception_vmexit(struct kvm_vcpu *vcpu,
nested_vmx_vmexit(vcpu, EXIT_REASON_EXCEPTION_NMI, intr_info, exit_qual);
}
/*
* Returns true if a debug trap is pending delivery.
*
* In KVM, debug traps bear an exception payload. As such, the class of a #DB
* exception may be inferred from the presence of an exception payload.
*/
static inline bool vmx_pending_dbg_trap(struct kvm_vcpu *vcpu)
{
return vcpu->arch.exception.pending &&
vcpu->arch.exception.nr == DB_VECTOR &&
vcpu->arch.exception.payload;
}
/*
* Certain VM-exits set the 'pending debug exceptions' field to indicate a
* recognized #DB (data or single-step) that has yet to be delivered. Since KVM
* represents these debug traps with a payload that is said to be compatible
* with the 'pending debug exceptions' field, write the payload to the VMCS
* field if a VM-exit is delivered before the debug trap.
*/
static void nested_vmx_update_pending_dbg(struct kvm_vcpu *vcpu)
{
if (vmx_pending_dbg_trap(vcpu))
vmcs_writel(GUEST_PENDING_DBG_EXCEPTIONS,
vcpu->arch.exception.payload);
}
static int vmx_check_nested_events(struct kvm_vcpu *vcpu, bool external_intr)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
@ -3587,6 +3615,7 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu, bool external_intr)
test_bit(KVM_APIC_INIT, &apic->pending_events)) {
if (block_nested_events)
return -EBUSY;
nested_vmx_update_pending_dbg(vcpu);
clear_bit(KVM_APIC_INIT, &apic->pending_events);
nested_vmx_vmexit(vcpu, EXIT_REASON_INIT_SIGNAL, 0, 0);
return 0;

5
arch/x86/kvm/vmx/vmx.c
View File

@ -2947,6 +2947,9 @@ void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
static int get_ept_level(struct kvm_vcpu *vcpu)
{
/* Nested EPT currently only supports 4-level walks. */
if (is_guest_mode(vcpu) && nested_cpu_has_ept(get_vmcs12(vcpu)))
return 4;
if (cpu_has_vmx_ept_5levels() && (cpuid_maxphyaddr(vcpu) > 48))
return 5;
return 4;
@ -4238,7 +4241,6 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
vmx->msr_ia32_umwait_control = 0;
vcpu->arch.microcode_version = 0x100000000ULL;
vmx->vcpu.arch.regs[VCPU_REGS_RDX] = get_rdx_init_val();
vmx->hv_deadline_tsc = -1;
kvm_set_cr8(vcpu, 0);
@ -6763,6 +6765,7 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
vmx->nested.posted_intr_nv = -1;
vmx->nested.current_vmptr = -1ull;
vcpu->arch.microcode_version = 0x100000000ULL;
vmx->msr_ia32_feature_control_valid_bits = FEAT_CTL_LOCKED;
/*

42
arch/x86/kvm/x86.c
View File

@ -438,6 +438,14 @@ void kvm_deliver_exception_payload(struct kvm_vcpu *vcpu)
* for #DB exceptions under VMX.
*/
vcpu->arch.dr6 ^= payload & DR6_RTM;
/*
* The #DB payload is defined as compatible with the 'pending
* debug exceptions' field under VMX, not DR6. While bit 12 is
* defined in the 'pending debug exceptions' field (enabled
* breakpoint), it is reserved and must be zero in DR6.
*/
vcpu->arch.dr6 &= ~BIT(12);
break;
case PF_VECTOR:
vcpu->arch.cr2 = payload;
@ -490,19 +498,7 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
vcpu->arch.exception.error_code = error_code;
vcpu->arch.exception.has_payload = has_payload;
vcpu->arch.exception.payload = payload;
/*
* In guest mode, payload delivery should be deferred,
* so that the L1 hypervisor can intercept #PF before
* CR2 is modified (or intercept #DB before DR6 is
* modified under nVMX). However, for ABI
* compatibility with KVM_GET_VCPU_EVENTS and
* KVM_SET_VCPU_EVENTS, we can't delay payload
* delivery unless userspace has enabled this
* functionality via the per-VM capability,
* KVM_CAP_EXCEPTION_PAYLOAD.
*/
if (!vcpu->kvm->arch.exception_payload_enabled ||
!is_guest_mode(vcpu))
if (!is_guest_mode(vcpu))
kvm_deliver_exception_payload(vcpu);
return;
}
@ -2448,7 +2444,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
vcpu->hv_clock.tsc_timestamp = tsc_timestamp;
vcpu->hv_clock.system_time = kernel_ns + v->kvm->arch.kvmclock_offset;
vcpu->last_guest_tsc = tsc_timestamp;
WARN_ON(vcpu->hv_clock.system_time < 0);
WARN_ON((s64)vcpu->hv_clock.system_time < 0);
/* If the host uses TSC clocksource, then it is stable */
pvclock_flags = 0;
@ -3795,6 +3791,21 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu,
{
process_nmi(vcpu);
/*
* In guest mode, payload delivery should be deferred,
* so that the L1 hypervisor can intercept #PF before
* CR2 is modified (or intercept #DB before DR6 is
* modified under nVMX). Unless the per-VM capability,
* KVM_CAP_EXCEPTION_PAYLOAD, is set, we may not defer the delivery of
* an exception payload and handle after a KVM_GET_VCPU_EVENTS. Since we
* opportunistically defer the exception payload, deliver it if the
* capability hasn't been requested before processing a
* KVM_GET_VCPU_EVENTS.
*/
if (!vcpu->kvm->arch.exception_payload_enabled &&
vcpu->arch.exception.pending && vcpu->arch.exception.has_payload)
kvm_deliver_exception_payload(vcpu);
/*
* The API doesn't provide the instruction length for software
* exceptions, so don't report them. As long as the guest RIP
@ -8942,7 +8953,6 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int idt_index,
kvm_rip_write(vcpu, ctxt->eip);
kvm_set_rflags(vcpu, ctxt->eflags);
kvm_make_request(KVM_REQ_EVENT, vcpu);
return 1;
}
EXPORT_SYMBOL_GPL(kvm_task_switch);
@ -10182,7 +10192,7 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work)
work->arch.cr3 != vcpu->arch.mmu->get_cr3(vcpu))
return;
vcpu->arch.mmu->page_fault(vcpu, work->cr2_or_gpa, 0, true);
kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, 0, true);
}
static inline u32 kvm_async_pf_hash_fn(gfn_t gfn)

3
tools/testing/selftests/kvm/Makefile
View File

@ -8,7 +8,7 @@ KSFT_KHDR_INSTALL := 1
UNAME_M := $(shell uname -m)
LIBKVM = lib/assert.c lib/elf.c lib/io.c lib/kvm_util.c lib/sparsebit.c
LIBKVM_x86_64 = lib/x86_64/processor.c lib/x86_64/vmx.c lib/x86_64/ucall.c
LIBKVM_x86_64 = lib/x86_64/processor.c lib/x86_64/vmx.c lib/x86_64/svm.c lib/x86_64/ucall.c
LIBKVM_aarch64 = lib/aarch64/processor.c lib/aarch64/ucall.c
LIBKVM_s390x = lib/s390x/processor.c lib/s390x/ucall.c
@ -26,6 +26,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/vmx_dirty_log_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_set_nested_state_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_tsc_adjust_test
TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test
TEST_GEN_PROGS_x86_64 += x86_64/svm_vmcall_test
TEST_GEN_PROGS_x86_64 += clear_dirty_log_test
TEST_GEN_PROGS_x86_64 += dirty_log_test
TEST_GEN_PROGS_x86_64 += kvm_create_max_vcpus

44
tools/testing/selftests/kvm/include/x86_64/processor.h
View File

@ -36,24 +36,24 @@
#define X86_CR4_SMAP (1ul << 21)
#define X86_CR4_PKE (1ul << 22)
/* The enum values match the intruction encoding of each register */
enum x86_register {
RAX = 0,
RCX,
RDX,
RBX,
RSP,
RBP,
RSI,
RDI,
R8,
R9,
R10,
R11,
R12,
R13,
R14,
R15,
/* General Registers in 64-Bit Mode */
struct gpr64_regs {
u64 rax;
u64 rcx;
u64 rdx;
u64 rbx;
u64 rsp;
u64 rbp;
u64 rsi;
u64 rdi;
u64 r8;
u64 r9;
u64 r10;
u64 r11;
u64 r12;
u64 r13;
u64 r14;
u64 r15;
};
struct desc64 {
@ -220,20 +220,20 @@ static inline void set_cr4(uint64_t val)
__asm__ __volatile__("mov %0, %%cr4" : : "r" (val) : "memory");
}
static inline uint64_t get_gdt_base(void)
static inline struct desc_ptr get_gdt(void)
{
struct desc_ptr gdt;
__asm__ __volatile__("sgdt %[gdt]"
: /* output */ [gdt]"=m"(gdt));
return gdt.address;
return gdt;
}
static inline uint64_t get_idt_base(void)
static inline struct desc_ptr get_idt(void)
{
struct desc_ptr idt;
__asm__ __volatile__("sidt %[idt]"
: /* output */ [idt]"=m"(idt));
return idt.address;
return idt;
}
#define SET_XMM(__var, __xmm) \

297
tools/testing/selftests/kvm/include/x86_64/svm.h Normal file
View File

@ -0,0 +1,297 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
* tools/testing/selftests/kvm/include/x86_64/svm.h
* This is a copy of arch/x86/include/asm/svm.h
*
*/
#ifndef SELFTEST_KVM_SVM_H
#define SELFTEST_KVM_SVM_H
enum {
INTERCEPT_INTR,
INTERCEPT_NMI,
INTERCEPT_SMI,
INTERCEPT_INIT,
INTERCEPT_VINTR,
INTERCEPT_SELECTIVE_CR0,
INTERCEPT_STORE_IDTR,
INTERCEPT_STORE_GDTR,
INTERCEPT_STORE_LDTR,
INTERCEPT_STORE_TR,
INTERCEPT_LOAD_IDTR,
INTERCEPT_LOAD_GDTR,
INTERCEPT_LOAD_LDTR,
INTERCEPT_LOAD_TR,
INTERCEPT_RDTSC,
INTERCEPT_RDPMC,
INTERCEPT_PUSHF,
INTERCEPT_POPF,
INTERCEPT_CPUID,
INTERCEPT_RSM,
INTERCEPT_IRET,
INTERCEPT_INTn,
INTERCEPT_INVD,
INTERCEPT_PAUSE,
INTERCEPT_HLT,
INTERCEPT_INVLPG,
INTERCEPT_INVLPGA,
INTERCEPT_IOIO_PROT,
INTERCEPT_MSR_PROT,
INTERCEPT_TASK_SWITCH,
INTERCEPT_FERR_FREEZE,
INTERCEPT_SHUTDOWN,
INTERCEPT_VMRUN,
INTERCEPT_VMMCALL,
INTERCEPT_VMLOAD,
INTERCEPT_VMSAVE,
INTERCEPT_STGI,
INTERCEPT_CLGI,
INTERCEPT_SKINIT,
INTERCEPT_RDTSCP,
INTERCEPT_ICEBP,
INTERCEPT_WBINVD,
INTERCEPT_MONITOR,
INTERCEPT_MWAIT,
INTERCEPT_MWAIT_COND,
INTERCEPT_XSETBV,
INTERCEPT_RDPRU,
};
struct __attribute__ ((__packed__)) vmcb_control_area {
u32 intercept_cr;
u32 intercept_dr;
u32 intercept_exceptions;
u64 intercept;
u8 reserved_1[40];
u16 pause_filter_thresh;
u16 pause_filter_count;
u64 iopm_base_pa;
u64 msrpm_base_pa;
u64 tsc_offset;
u32 asid;
u8 tlb_ctl;
u8 reserved_2[3];
u32 int_ctl;
u32 int_vector;
u32 int_state;
u8 reserved_3[4];
u32 exit_code;
u32 exit_code_hi;
u64 exit_info_1;
u64 exit_info_2;
u32 exit_int_info;
u32 exit_int_info_err;
u64 nested_ctl;
u64 avic_vapic_bar;
u8 reserved_4[8];
u32 event_inj;
u32 event_inj_err;
u64 nested_cr3;
u64 virt_ext;
u32 clean;
u32 reserved_5;
u64 next_rip;
u8 insn_len;
u8 insn_bytes[15];
u64 avic_backing_page; /* Offset 0xe0 */
u8 reserved_6[8]; /* Offset 0xe8 */
u64 avic_logical_id; /* Offset 0xf0 */
u64 avic_physical_id; /* Offset 0xf8 */
u8 reserved_7[768];
};
#define TLB_CONTROL_DO_NOTHING 0
#define TLB_CONTROL_FLUSH_ALL_ASID 1
#define TLB_CONTROL_FLUSH_ASID 3
#define TLB_CONTROL_FLUSH_ASID_LOCAL 7
#define V_TPR_MASK 0x0f
#define V_IRQ_SHIFT 8
#define V_IRQ_MASK (1 << V_IRQ_SHIFT)
#define V_GIF_SHIFT 9
#define V_GIF_MASK (1 << V_GIF_SHIFT)
#define V_INTR_PRIO_SHIFT 16
#define V_INTR_PRIO_MASK (0x0f << V_INTR_PRIO_SHIFT)
#define V_IGN_TPR_SHIFT 20
#define V_IGN_TPR_MASK (1 << V_IGN_TPR_SHIFT)
#define V_INTR_MASKING_SHIFT 24
#define V_INTR_MASKING_MASK (1 << V_INTR_MASKING_SHIFT)
#define V_GIF_ENABLE_SHIFT 25
#define V_GIF_ENABLE_MASK (1 << V_GIF_ENABLE_SHIFT)
#define AVIC_ENABLE_SHIFT 31
#define AVIC_ENABLE_MASK (1 << AVIC_ENABLE_SHIFT)
#define LBR_CTL_ENABLE_MASK BIT_ULL(0)
#define VIRTUAL_VMLOAD_VMSAVE_ENABLE_MASK BIT_ULL(1)
#define SVM_INTERRUPT_SHADOW_MASK 1
#define SVM_IOIO_STR_SHIFT 2
#define SVM_IOIO_REP_SHIFT 3
#define SVM_IOIO_SIZE_SHIFT 4
#define SVM_IOIO_ASIZE_SHIFT 7
#define SVM_IOIO_TYPE_MASK 1
#define SVM_IOIO_STR_MASK (1 << SVM_IOIO_STR_SHIFT)
#define SVM_IOIO_REP_MASK (1 << SVM_IOIO_REP_SHIFT)
#define SVM_IOIO_SIZE_MASK (7 << SVM_IOIO_SIZE_SHIFT)
#define SVM_IOIO_ASIZE_MASK (7 << SVM_IOIO_ASIZE_SHIFT)
#define SVM_VM_CR_VALID_MASK 0x001fULL
#define SVM_VM_CR_SVM_LOCK_MASK 0x0008ULL
#define SVM_VM_CR_SVM_DIS_MASK 0x0010ULL
#define SVM_NESTED_CTL_NP_ENABLE BIT(0)
#define SVM_NESTED_CTL_SEV_ENABLE BIT(1)
struct __attribute__ ((__packed__)) vmcb_seg {
u16 selector;
u16 attrib;
u32 limit;
u64 base;
};
struct __attribute__ ((__packed__)) vmcb_save_area {
struct vmcb_seg es;
struct vmcb_seg cs;
struct vmcb_seg ss;
struct vmcb_seg ds;
struct vmcb_seg fs;
struct vmcb_seg gs;
struct vmcb_seg gdtr;
struct vmcb_seg ldtr;
struct vmcb_seg idtr;
struct vmcb_seg tr;
u8 reserved_1[43];
u8 cpl;
u8 reserved_2[4];
u64 efer;
u8 reserved_3[112];
u64 cr4;
u64 cr3;
u64 cr0;
u64 dr7;
u64 dr6;
u64 rflags;
u64 rip;
u8 reserved_4[88];
u64 rsp;
u8 reserved_5[24];
u64 rax;
u64 star;
u64 lstar;
u64 cstar;
u64 sfmask;
u64 kernel_gs_base;
u64 sysenter_cs;
u64 sysenter_esp;
u64 sysenter_eip;
u64 cr2;
u8 reserved_6[32];
u64 g_pat;
u64 dbgctl;
u64 br_from;
u64 br_to;
u64 last_excp_from;
u64 last_excp_to;
};
struct __attribute__ ((__packed__)) vmcb {
struct vmcb_control_area control;
struct vmcb_save_area save;
};
#define SVM_CPUID_FUNC 0x8000000a
#define SVM_VM_CR_SVM_DISABLE 4
#define SVM_SELECTOR_S_SHIFT 4
#define SVM_SELECTOR_DPL_SHIFT 5
#define SVM_SELECTOR_P_SHIFT 7
#define SVM_SELECTOR_AVL_SHIFT 8
#define SVM_SELECTOR_L_SHIFT 9
#define SVM_SELECTOR_DB_SHIFT 10
#define SVM_SELECTOR_G_SHIFT 11
#define SVM_SELECTOR_TYPE_MASK (0xf)
#define SVM_SELECTOR_S_MASK (1 << SVM_SELECTOR_S_SHIFT)
#define SVM_SELECTOR_DPL_MASK (3 << SVM_SELECTOR_DPL_SHIFT)
#define SVM_SELECTOR_P_MASK (1 << SVM_SELECTOR_P_SHIFT)
#define SVM_SELECTOR_AVL_MASK (1 << SVM_SELECTOR_AVL_SHIFT)
#define SVM_SELECTOR_L_MASK (1 << SVM_SELECTOR_L_SHIFT)
#define SVM_SELECTOR_DB_MASK (1 << SVM_SELECTOR_DB_SHIFT)
#define SVM_SELECTOR_G_MASK (1 << SVM_SELECTOR_G_SHIFT)
#define SVM_SELECTOR_WRITE_MASK (1 << 1)
#define SVM_SELECTOR_READ_MASK SVM_SELECTOR_WRITE_MASK
#define SVM_SELECTOR_CODE_MASK (1 << 3)
#define INTERCEPT_CR0_READ 0
#define INTERCEPT_CR3_READ 3
#define INTERCEPT_CR4_READ 4
#define INTERCEPT_CR8_READ 8
#define INTERCEPT_CR0_WRITE (16 + 0)
#define INTERCEPT_CR3_WRITE (16 + 3)
#define INTERCEPT_CR4_WRITE (16 + 4)
#define INTERCEPT_CR8_WRITE (16 + 8)
#define INTERCEPT_DR0_READ 0
#define INTERCEPT_DR1_READ 1
#define INTERCEPT_DR2_READ 2
#define INTERCEPT_DR3_READ 3
#define INTERCEPT_DR4_READ 4
#define INTERCEPT_DR5_READ 5
#define INTERCEPT_DR6_READ 6
#define INTERCEPT_DR7_READ 7
#define INTERCEPT_DR0_WRITE (16 + 0)
#define INTERCEPT_DR1_WRITE (16 + 1)
#define INTERCEPT_DR2_WRITE (16 + 2)
#define INTERCEPT_DR3_WRITE (16 + 3)
#define INTERCEPT_DR4_WRITE (16 + 4)
#define INTERCEPT_DR5_WRITE (16 + 5)
#define INTERCEPT_DR6_WRITE (16 + 6)
#define INTERCEPT_DR7_WRITE (16 + 7)
#define SVM_EVTINJ_VEC_MASK 0xff
#define SVM_EVTINJ_TYPE_SHIFT 8
#define SVM_EVTINJ_TYPE_MASK (7 << SVM_EVTINJ_TYPE_SHIFT)
#define SVM_EVTINJ_TYPE_INTR (0 << SVM_EVTINJ_TYPE_SHIFT)
#define SVM_EVTINJ_TYPE_NMI (2 << SVM_EVTINJ_TYPE_SHIFT)
#define SVM_EVTINJ_TYPE_EXEPT (3 << SVM_EVTINJ_TYPE_SHIFT)
#define SVM_EVTINJ_TYPE_SOFT (4 << SVM_EVTINJ_TYPE_SHIFT)
#define SVM_EVTINJ_VALID (1 << 31)
#define SVM_EVTINJ_VALID_ERR (1 << 11)
#define SVM_EXITINTINFO_VEC_MASK SVM_EVTINJ_VEC_MASK
#define SVM_EXITINTINFO_TYPE_MASK SVM_EVTINJ_TYPE_MASK
#define SVM_EXITINTINFO_TYPE_INTR SVM_EVTINJ_TYPE_INTR
#define SVM_EXITINTINFO_TYPE_NMI SVM_EVTINJ_TYPE_NMI
#define SVM_EXITINTINFO_TYPE_EXEPT SVM_EVTINJ_TYPE_EXEPT
#define SVM_EXITINTINFO_TYPE_SOFT SVM_EVTINJ_TYPE_SOFT
#define SVM_EXITINTINFO_VALID SVM_EVTINJ_VALID
#define SVM_EXITINTINFO_VALID_ERR SVM_EVTINJ_VALID_ERR
#define SVM_EXITINFOSHIFT_TS_REASON_IRET 36
#define SVM_EXITINFOSHIFT_TS_REASON_JMP 38
#define SVM_EXITINFOSHIFT_TS_HAS_ERROR_CODE 44
#define SVM_EXITINFO_REG_MASK 0x0F
#define SVM_CR0_SELECTIVE_MASK (X86_CR0_TS | X86_CR0_MP)
#endif /* SELFTEST_KVM_SVM_H */

38
tools/testing/selftests/kvm/include/x86_64/svm_util.h Normal file
View File

@ -0,0 +1,38 @@
/* SPDX-License-Identifier: GPL-2.0-only */
/*
* tools/testing/selftests/kvm/include/x86_64/svm_utils.h
* Header for nested SVM testing
*
* Copyright (C) 2020, Red Hat, Inc.
*/
#ifndef SELFTEST_KVM_SVM_UTILS_H
#define SELFTEST_KVM_SVM_UTILS_H
#include <stdint.h>
#include "svm.h"
#include "processor.h"
#define CPUID_SVM_BIT 2
#define CPUID_SVM BIT_ULL(CPUID_SVM_BIT)
#define SVM_EXIT_VMMCALL 0x081
struct svm_test_data {
/* VMCB */
struct vmcb *vmcb; /* gva */
void *vmcb_hva;
uint64_t vmcb_gpa;
/* host state-save area */
struct vmcb_save_area *save_area; /* gva */
void *save_area_hva;
uint64_t save_area_gpa;
};
struct svm_test_data *vcpu_alloc_svm(struct kvm_vm *vm, vm_vaddr_t *p_svm_gva);
void generic_svm_setup(struct svm_test_data *svm, void *guest_rip, void *guest_rsp);
void run_guest(struct vmcb *vmcb, uint64_t vmcb_gpa);
void nested_svm_check_supported(void);
#endif /* SELFTEST_KVM_SVM_UTILS_H */

161
tools/testing/selftests/kvm/lib/x86_64/svm.c Normal file
View File

@ -0,0 +1,161 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* tools/testing/selftests/kvm/lib/x86_64/svm.c
* Helpers used for nested SVM testing
* Largely inspired from KVM unit test svm.c
*
* Copyright (C) 2020, Red Hat, Inc.
*/
#include "test_util.h"
#include "kvm_util.h"
#include "../kvm_util_internal.h"
#include "processor.h"
#include "svm_util.h"
struct gpr64_regs guest_regs;
u64 rflags;
/* Allocate memory regions for nested SVM tests.
*
* Input Args:
* vm - The VM to allocate guest-virtual addresses in.
*
* Output Args:
* p_svm_gva - The guest virtual address for the struct svm_test_data.
*
* Return:
* Pointer to structure with the addresses of the SVM areas.
*/
struct svm_test_data *
vcpu_alloc_svm(struct kvm_vm *vm, vm_vaddr_t *p_svm_gva)
{
vm_vaddr_t svm_gva = vm_vaddr_alloc(vm, getpagesize(),
0x10000, 0, 0);
struct svm_test_data *svm = addr_gva2hva(vm, svm_gva);
svm->vmcb = (void *)vm_vaddr_alloc(vm, getpagesize(),
0x10000, 0, 0);
svm->vmcb_hva = addr_gva2hva(vm, (uintptr_t)svm->vmcb);
svm->vmcb_gpa = addr_gva2gpa(vm, (uintptr_t)svm->vmcb);
svm->save_area = (void *)vm_vaddr_alloc(vm, getpagesize(),
0x10000, 0, 0);
svm->save_area_hva = addr_gva2hva(vm, (uintptr_t)svm->save_area);
svm->save_area_gpa = addr_gva2gpa(vm, (uintptr_t)svm->save_area);
*p_svm_gva = svm_gva;
return svm;
}
static void vmcb_set_seg(struct vmcb_seg *seg, u16 selector,
u64 base, u32 limit, u32 attr)
{
seg->selector = selector;
seg->attrib = attr;
seg->limit = limit;
seg->base = base;
}
void generic_svm_setup(struct svm_test_data *svm, void *guest_rip, void *guest_rsp)
{
struct vmcb *vmcb = svm->vmcb;
uint64_t vmcb_gpa = svm->vmcb_gpa;
struct vmcb_save_area *save = &vmcb->save;
struct vmcb_control_area *ctrl = &vmcb->control;
u32 data_seg_attr = 3 | SVM_SELECTOR_S_MASK | SVM_SELECTOR_P_MASK
| SVM_SELECTOR_DB_MASK | SVM_SELECTOR_G_MASK;
u32 code_seg_attr = 9 | SVM_SELECTOR_S_MASK | SVM_SELECTOR_P_MASK
| SVM_SELECTOR_L_MASK | SVM_SELECTOR_G_MASK;
uint64_t efer;
efer = rdmsr(MSR_EFER);
wrmsr(MSR_EFER, efer | EFER_SVME);
wrmsr(MSR_VM_HSAVE_PA, svm->save_area_gpa);
memset(vmcb, 0, sizeof(*vmcb));
asm volatile ("vmsave\n\t" : : "a" (vmcb_gpa) : "memory");
vmcb_set_seg(&save->es, get_es(), 0, -1U, data_seg_attr);
vmcb_set_seg(&save->cs, get_cs(), 0, -1U, code_seg_attr);
vmcb_set_seg(&save->ss, get_ss(), 0, -1U, data_seg_attr);
vmcb_set_seg(&save->ds, get_ds(), 0, -1U, data_seg_attr);
vmcb_set_seg(&save->gdtr, 0, get_gdt().address, get_gdt().size, 0);
vmcb_set_seg(&save->idtr, 0, get_idt().address, get_idt().size, 0);
ctrl->asid = 1;
save->cpl = 0;
save->efer = rdmsr(MSR_EFER);
asm volatile ("mov %%cr4, %0" : "=r"(save->cr4) : : "memory");
asm volatile ("mov %%cr3, %0" : "=r"(save->cr3) : : "memory");
asm volatile ("mov %%cr0, %0" : "=r"(save->cr0) : : "memory");
asm volatile ("mov %%dr7, %0" : "=r"(save->dr7) : : "memory");
asm volatile ("mov %%dr6, %0" : "=r"(save->dr6) : : "memory");
asm volatile ("mov %%cr2, %0" : "=r"(save->cr2) : : "memory");
save->g_pat = rdmsr(MSR_IA32_CR_PAT);
save->dbgctl = rdmsr(MSR_IA32_DEBUGCTLMSR);
ctrl->intercept = (1ULL << INTERCEPT_VMRUN) |
(1ULL << INTERCEPT_VMMCALL);
vmcb->save.rip = (u64)guest_rip;
vmcb->save.rsp = (u64)guest_rsp;
guest_regs.rdi = (u64)svm;
}
/*
* save/restore 64-bit general registers except rax, rip, rsp
* which are directly handed through the VMCB guest processor state
*/
#define SAVE_GPR_C \
"xchg %%rbx, guest_regs+0x20\n\t" \
"xchg %%rcx, guest_regs+0x10\n\t" \
"xchg %%rdx, guest_regs+0x18\n\t" \
"xchg %%rbp, guest_regs+0x30\n\t" \
"xchg %%rsi, guest_regs+0x38\n\t" \
"xchg %%rdi, guest_regs+0x40\n\t" \
"xchg %%r8, guest_regs+0x48\n\t" \
"xchg %%r9, guest_regs+0x50\n\t" \
"xchg %%r10, guest_regs+0x58\n\t" \
"xchg %%r11, guest_regs+0x60\n\t" \
"xchg %%r12, guest_regs+0x68\n\t" \
"xchg %%r13, guest_regs+0x70\n\t" \
"xchg %%r14, guest_regs+0x78\n\t" \
"xchg %%r15, guest_regs+0x80\n\t"
#define LOAD_GPR_C SAVE_GPR_C
/*
* selftests do not use interrupts so we dropped clgi/sti/cli/stgi
* for now. registers involved in LOAD/SAVE_GPR_C are eventually
* unmodified so they do not need to be in the clobber list.
*/
void run_guest(struct vmcb *vmcb, uint64_t vmcb_gpa)
{
asm volatile (
"vmload\n\t"
"mov rflags, %%r15\n\t" // rflags
"mov %%r15, 0x170(%[vmcb])\n\t"
"mov guest_regs, %%r15\n\t" // rax
"mov %%r15, 0x1f8(%[vmcb])\n\t"
LOAD_GPR_C
"vmrun\n\t"
SAVE_GPR_C
"mov 0x170(%[vmcb]), %%r15\n\t" // rflags
"mov %%r15, rflags\n\t"
"mov 0x1f8(%[vmcb]), %%r15\n\t" // rax
"mov %%r15, guest_regs\n\t"
"vmsave\n\t"
: : [vmcb] "r" (vmcb), [vmcb_gpa] "a" (vmcb_gpa)
: "r15", "memory");
}
void nested_svm_check_supported(void)
{
struct kvm_cpuid_entry2 *entry =
kvm_get_supported_cpuid_entry(0x80000001);
if (!(entry->ecx & CPUID_SVM)) {
fprintf(stderr, "nested SVM not enabled, skipping test\n");
exit(KSFT_SKIP);
}
}

6
tools/testing/selftests/kvm/lib/x86_64/vmx.c
View File

@ -288,9 +288,9 @@ static inline void init_vmcs_host_state(void)
vmwrite(HOST_FS_BASE, rdmsr(MSR_FS_BASE));
vmwrite(HOST_GS_BASE, rdmsr(MSR_GS_BASE));
vmwrite(HOST_TR_BASE,
get_desc64_base((struct desc64 *)(get_gdt_base() + get_tr())));
vmwrite(HOST_GDTR_BASE, get_gdt_base());
vmwrite(HOST_IDTR_BASE, get_idt_base());
get_desc64_base((struct desc64 *)(get_gdt().address + get_tr())));
vmwrite(HOST_GDTR_BASE, get_gdt().address);
vmwrite(HOST_IDTR_BASE, get_idt().address);
vmwrite(HOST_IA32_SYSENTER_ESP, rdmsr(MSR_IA32_SYSENTER_ESP));
vmwrite(HOST_IA32_SYSENTER_EIP, rdmsr(MSR_IA32_SYSENTER_EIP));
}

79
tools/testing/selftests/kvm/x86_64/svm_vmcall_test.c Normal file
View File

@ -0,0 +1,79 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* svm_vmcall_test
*
* Copyright (C) 2020, Red Hat, Inc.
*
* Nested SVM testing: VMCALL
*/
#include "test_util.h"
#include "kvm_util.h"
#include "processor.h"
#include "svm_util.h"
#define VCPU_ID 5
static struct kvm_vm *vm;
static void l2_guest_code(struct svm_test_data *svm)
{
__asm__ __volatile__("vmcall");
}
static void l1_guest_code(struct svm_test_data *svm)
{
#define L2_GUEST_STACK_SIZE 64
unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
struct vmcb *vmcb = svm->vmcb;
/* Prepare for L2 execution. */
generic_svm_setup(svm, l2_guest_code,
&l2_guest_stack[L2_GUEST_STACK_SIZE]);
run_guest(vmcb, svm->vmcb_gpa);
GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_VMMCALL);
GUEST_DONE();
}
int main(int argc, char *argv[])
{
vm_vaddr_t svm_gva;
nested_svm_check_supported();
vm = vm_create_default(VCPU_ID, 0, (void *) l1_guest_code);
vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
vcpu_alloc_svm(vm, &svm_gva);
vcpu_args_set(vm, VCPU_ID, 1, svm_gva);
for (;;) {
volatile struct kvm_run *run = vcpu_state(vm, VCPU_ID);
struct ucall uc;
vcpu_run(vm, VCPU_ID);
TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
"Got exit_reason other than KVM_EXIT_IO: %u (%s)\n",
run->exit_reason,
exit_reason_str(run->exit_reason));
switch (get_ucall(vm, VCPU_ID, &uc)) {
case UCALL_ABORT:
TEST_ASSERT(false, "%s",
(const char *)uc.args[0]);
/* NOT REACHED */
case UCALL_SYNC:
break;
case UCALL_DONE:
goto done;
default:
TEST_ASSERT(false,
"Unknown ucall 0x%x.", uc.cmd);
}
}
done:
kvm_vm_free(vm);
return 0;
}

12
virt/kvm/arm/vgic/vgic-mmio.c
View File

@ -179,18 +179,6 @@ unsigned long vgic_mmio_read_pending(struct kvm_vcpu *vcpu,
return value;
}
/*
* This function will return the VCPU that performed the MMIO access and
* trapped from within the VM, and will return NULL if this is a userspace
* access.
*
* We can disable preemption locally around accessing the per-CPU variable,
* and use the resolved vcpu pointer after enabling preemption again, because
* even if the current thread is migrated to another CPU, reading the per-CPU
* value later will give us the same value as we update the per-CPU variable
* in the preempt notifier handlers.
*/
/* Must be called with irq->irq_lock held */
static void vgic_hw_irq_spending(struct kvm_vcpu *vcpu, struct vgic_irq *irq,
bool is_uaccess)

16
virt/kvm/kvm_main.c
View File

@ -4409,12 +4409,22 @@ static void kvm_sched_out(struct preempt_notifier *pn,
/**
* kvm_get_running_vcpu - get the vcpu running on the current CPU.
* Thanks to preempt notifiers, this can also be called from
* preemptible context.
*
* We can disable preemption locally around accessing the per-CPU variable,
* and use the resolved vcpu pointer after enabling preemption again,
* because even if the current thread is migrated to another CPU, reading
* the per-CPU value later will give us the same value as we update the
* per-CPU variable in the preempt notifier handlers.
*/
struct kvm_vcpu *kvm_get_running_vcpu(void)
{
return __this_cpu_read(kvm_running_vcpu);
struct kvm_vcpu *vcpu;
preempt_disable();
vcpu = __this_cpu_read(kvm_running_vcpu);
preempt_enable();
return vcpu;
}
/**