Commit Graph

529 Commits

Author SHA1 Message Date
Changyuan Lyu
03bd36a387 KVM: Documentation: Enumerate allowed value macros of irq_type
The expression `irq_type[n]` may confuse readers to interpret `n`
as the bit position and think of CPU = 1 << 0, SPI = 1 << 1, and
PPI = 1 << 2.

Since arch/arm64/include/uapi/asm/kvm.h already has macro definitions
for the allowed values, this commit uses these symbols to clear up
the ambiguity.

Signed-off-by: Changyuan Lyu <changyuanl@google.com>
Link: https://lore.kernel.org/r/20240623164542.2999626-2-changyuanl@google.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
2024-06-28 22:00:18 +00:00
Changyuan Lyu
dc1d234cdd KVM: Documentation: Fix typo BFD
BDF is the acronym for Bus, Device, Function.

Signed-off-by: Changyuan Lyu <changyuanl@google.com>
Link: https://lore.kernel.org/r/20240623164542.2999626-1-changyuanl@google.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
2024-06-28 22:00:13 +00:00
Linus Torvalds
ff2632d7d0 powerpc updates for 6.10
- Enable BPF Kernel Functions (kfuncs) in the powerpc BPF JIT.
 
  - Allow per-process DEXCR (Dynamic Execution Control Register) settings via
    prctl, notably NPHIE which controls hashst/hashchk for ROP protection.
 
  - Install powerpc selftests in sub-directories. Note this changes the way
    run_kselftest.sh needs to be invoked for powerpc selftests.
 
  - Change fadump (Firmware Assisted Dump) to better handle memory add/remove.
 
  - Add support for passing additional parameters to the fadump kernel.
 
  - Add support for updating the kdump image on CPU/memory add/remove events.
 
  - Other small features, cleanups and fixes.
 
 Thanks to: Andrew Donnellan, Andy Shevchenko, Aneesh Kumar K.V, Arnd Bergmann,
 Benjamin Gray, Bjorn Helgaas, Christian Zigotzky, Christophe Jaillet, Christophe
 Leroy, Colin Ian King, Cédric Le Goater, Dr. David Alan Gilbert, Erhard Furtner,
 Frank Li, GUO Zihua, Ganesh Goudar, Geoff Levand, Ghanshyam Agrawal, Greg Kurz,
 Hari Bathini, Joel Stanley, Justin Stitt, Kunwu Chan, Li Yang, Lidong Zhong,
 Madhavan Srinivasan, Mahesh Salgaonkar, Masahiro Yamada, Matthias Schiffer,
 Naresh Kamboju, Nathan Chancellor, Nathan Lynch, Naveen N Rao, Nicholas
 Miehlbradt, Ran Wang, Randy Dunlap, Ritesh Harjani, Sachin Sant, Shirisha Ganta,
 Shrikanth Hegde, Sourabh Jain, Stephen Rothwell, sundar, Thorsten Blum, Vaibhav
 Jain, Xiaowei Bao, Yang Li, Zhao Chenhui.
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Merge tag 'powerpc-6.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc updates from Michael Ellerman:

 - Enable BPF Kernel Functions (kfuncs) in the powerpc BPF JIT.

 - Allow per-process DEXCR (Dynamic Execution Control Register) settings
   via prctl, notably NPHIE which controls hashst/hashchk for ROP
   protection.

 - Install powerpc selftests in sub-directories. Note this changes the
   way run_kselftest.sh needs to be invoked for powerpc selftests.

 - Change fadump (Firmware Assisted Dump) to better handle memory
   add/remove.

 - Add support for passing additional parameters to the fadump kernel.

 - Add support for updating the kdump image on CPU/memory add/remove
   events.

 - Other small features, cleanups and fixes.

Thanks to Andrew Donnellan, Andy Shevchenko, Aneesh Kumar K.V, Arnd
Bergmann, Benjamin Gray, Bjorn Helgaas, Christian Zigotzky, Christophe
Jaillet, Christophe Leroy, Colin Ian King, Cédric Le Goater, Dr. David
Alan Gilbert, Erhard Furtner, Frank Li, GUO Zihua, Ganesh Goudar, Geoff
Levand, Ghanshyam Agrawal, Greg Kurz, Hari Bathini, Joel Stanley, Justin
Stitt, Kunwu Chan, Li Yang, Lidong Zhong, Madhavan Srinivasan, Mahesh
Salgaonkar, Masahiro Yamada, Matthias Schiffer, Naresh Kamboju, Nathan
Chancellor, Nathan Lynch, Naveen N Rao, Nicholas Miehlbradt, Ran Wang,
Randy Dunlap, Ritesh Harjani, Sachin Sant, Shirisha Ganta, Shrikanth
Hegde, Sourabh Jain, Stephen Rothwell, sundar, Thorsten Blum, Vaibhav
Jain, Xiaowei Bao, Yang Li, and Zhao Chenhui.

* tag 'powerpc-6.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (85 commits)
  powerpc/fadump: Fix section mismatch warning
  powerpc/85xx: fix compile error without CONFIG_CRASH_DUMP
  powerpc/fadump: update documentation about bootargs_append
  powerpc/fadump: pass additional parameters when fadump is active
  powerpc/fadump: setup additional parameters for dump capture kernel
  powerpc/pseries/fadump: add support for multiple boot memory regions
  selftests/powerpc/dexcr: Fix spelling mistake "predicition" -> "prediction"
  KVM: PPC: Book3S HV nestedv2: Fix an error handling path in gs_msg_ops_kvmhv_nestedv2_config_fill_info()
  KVM: PPC: Fix documentation for ppc mmu caps
  KVM: PPC: code cleanup for kvmppc_book3s_irqprio_deliver
  KVM: PPC: Book3S HV nestedv2: Cancel pending DEC exception
  powerpc/xmon: Check cpu id in commands "c#", "dp#" and "dx#"
  powerpc/code-patching: Use dedicated memory routines for patching
  powerpc/code-patching: Test patch_instructions() during boot
  powerpc64/kasan: Pass virtual addresses to kasan_init_phys_region()
  powerpc: rename SPRN_HID2 define to SPRN_HID2_750FX
  powerpc: Fix typos
  powerpc/eeh: Fix spelling of the word "auxillary" and update comment
  macintosh/ams: Fix unused variable warning
  powerpc/Makefile: Remove bits related to the previous use of -mcmodel=large
  ...
2024-05-17 09:05:46 -07:00
Paolo Bonzini
f4bc1373d5 KVM cleanups for 6.10:
- Misc cleanups extracted from the "exit on missing userspace mapping" series,
    which has been put on hold in anticipation of a "KVM Userfault" approach,
    which should provide a superset of functionality.
 
  - Remove kvm_make_all_cpus_request_except(), which got added to hack around an
    AVIC bug, and then became dead code when a more robust fix came along.
 
  - Fix a goof in the KVM_CREATE_GUEST_MEMFD documentation.
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Merge tag 'kvm-x86-generic-6.10' of https://github.com/kvm-x86/linux into HEAD

KVM cleanups for 6.10:

 - Misc cleanups extracted from the "exit on missing userspace mapping" series,
   which has been put on hold in anticipation of a "KVM Userfault" approach,
   which should provide a superset of functionality.

 - Remove kvm_make_all_cpus_request_except(), which got added to hack around an
   AVIC bug, and then became dead code when a more robust fix came along.

 - Fix a goof in the KVM_CREATE_GUEST_MEMFD documentation.
2024-05-12 03:16:47 -04:00
Paolo Bonzini
e5f62e27b1 KVM/arm64 updates for Linux 6.10
- Move a lot of state that was previously stored on a per vcpu
   basis into a per-CPU area, because it is only pertinent to the
   host while the vcpu is loaded. This results in better state
   tracking, and a smaller vcpu structure.
 
 - Add full handling of the ERET/ERETAA/ERETAB instructions in
   nested virtualisation. The last two instructions also require
   emulating part of the pointer authentication extension.
   As a result, the trap handling of pointer authentication has
   been greattly simplified.
 
 - Turn the global (and not very scalable) LPI translation cache
   into a per-ITS, scalable cache, making non directly injected
   LPIs much cheaper to make visible to the vcpu.
 
 - A batch of pKVM patches, mostly fixes and cleanups, as the
   upstreaming process seems to be resuming. Fingers crossed!
 
 - Allocate PPIs and SGIs outside of the vcpu structure, allowing
   for smaller EL2 mapping and some flexibility in implementing
   more or less than 32 private IRQs.
 
 - Purge stale mpidr_data if a vcpu is created after the MPIDR
   map has been created.
 
 - Preserve vcpu-specific ID registers across a vcpu reset.
 
 - Various minor cleanups and improvements.
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Merge tag 'kvmarm-6.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 updates for Linux 6.10

- Move a lot of state that was previously stored on a per vcpu
  basis into a per-CPU area, because it is only pertinent to the
  host while the vcpu is loaded. This results in better state
  tracking, and a smaller vcpu structure.

- Add full handling of the ERET/ERETAA/ERETAB instructions in
  nested virtualisation. The last two instructions also require
  emulating part of the pointer authentication extension.
  As a result, the trap handling of pointer authentication has
  been greattly simplified.

- Turn the global (and not very scalable) LPI translation cache
  into a per-ITS, scalable cache, making non directly injected
  LPIs much cheaper to make visible to the vcpu.

- A batch of pKVM patches, mostly fixes and cleanups, as the
  upstreaming process seems to be resuming. Fingers crossed!

- Allocate PPIs and SGIs outside of the vcpu structure, allowing
  for smaller EL2 mapping and some flexibility in implementing
  more or less than 32 private IRQs.

- Purge stale mpidr_data if a vcpu is created after the MPIDR
  map has been created.

- Preserve vcpu-specific ID registers across a vcpu reset.

- Various minor cleanups and improvements.
2024-05-12 03:15:53 -04:00
Michael Roth
4af663c2f6 KVM: SEV: Allow per-guest configuration of GHCB protocol version
The GHCB protocol version may be different from one guest to the next.
Add a field to track it for each KVM instance and extend KVM_SEV_INIT2
to allow it to be configured by userspace.

Now that all SEV-ES support for GHCB protocol version 2 is in place, go
ahead and default to it when creating SEV-ES guests through the new
KVM_SEV_INIT2 interface. Keep the older KVM_SEV_ES_INIT interface
restricted to GHCB protocol version 1.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Message-ID: <20240501071048.2208265-5-michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-05-07 13:28:05 -04:00
Joel Stanley
651d61bc8b KVM: PPC: Fix documentation for ppc mmu caps
The documentation mentions KVM_CAP_PPC_RADIX_MMU, but the defines in the
kvm headers spell it KVM_CAP_PPC_MMU_RADIX. Similarly with
KVM_CAP_PPC_MMU_HASH_V3.

Fixes: c927013227 ("KVM: PPC: Book3S HV: Add userspace interfaces for POWER9 MMU")
Signed-off-by: Joel Stanley <joel@jms.id.au>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230411061446.26324-1-joel@jms.id.au
2024-05-08 01:28:00 +10:00
Carlos López
2098acaf24 KVM: fix documentation for KVM_CREATE_GUEST_MEMFD
The KVM_CREATE_GUEST_MEMFD ioctl returns a file descriptor, and is
documented as such in the description. However, the "Returns" field
in the documentation states that the ioctl returns 0 on success.
Update this to match the description.

Signed-off-by: Carlos López <clopez@suse.de>
Fixes: a7800aa80e ("KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory")
Link: https://lore.kernel.org/r/20240424103317.28522-1-clopez@suse.de
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-05-03 15:11:23 -07:00
Marc Zyngier
8540bd1b99 Merge branch kvm-arm64/pkvm-6.10 into kvmarm-master/next
* kvm-arm64/pkvm-6.10: (25 commits)
  : .
  : At last, a bunch of pKVM patches, courtesy of Fuad Tabba.
  : From the cover letter:
  :
  : "This series is a bit of a bombay-mix of patches we've been
  : carrying. There's no one overarching theme, but they do improve
  : the code by fixing existing bugs in pKVM, refactoring code to
  : make it more readable and easier to re-use for pKVM, or adding
  : functionality to the existing pKVM code upstream."
  : .
  KVM: arm64: Force injection of a data abort on NISV MMIO exit
  KVM: arm64: Restrict supported capabilities for protected VMs
  KVM: arm64: Refactor setting the return value in kvm_vm_ioctl_enable_cap()
  KVM: arm64: Document the KVM/arm64-specific calls in hypercalls.rst
  KVM: arm64: Rename firmware pseudo-register documentation file
  KVM: arm64: Reformat/beautify PTP hypercall documentation
  KVM: arm64: Clarify rationale for ZCR_EL1 value restored on guest exit
  KVM: arm64: Introduce and use predicates that check for protected VMs
  KVM: arm64: Add is_pkvm_initialized() helper
  KVM: arm64: Simplify vgic-v3 hypercalls
  KVM: arm64: Move setting the page as dirty out of the critical section
  KVM: arm64: Change kvm_handle_mmio_return() return polarity
  KVM: arm64: Fix comment for __pkvm_vcpu_init_traps()
  KVM: arm64: Prevent kmemleak from accessing .hyp.data
  KVM: arm64: Do not map the host fpsimd state to hyp in pKVM
  KVM: arm64: Rename __tlb_switch_to_{guest,host}() in VHE
  KVM: arm64: Support TLB invalidation in guest context
  KVM: arm64: Avoid BBM when changing only s/w bits in Stage-2 PTE
  KVM: arm64: Check for PTE validity when checking for executable/cacheable
  KVM: arm64: Avoid BUG-ing from the host abort path
  ...

Signed-off-by: Marc Zyngier <maz@kernel.org>
2024-05-03 11:39:52 +01:00
Marc Zyngier
3b467b1658 KVM: arm64: Force injection of a data abort on NISV MMIO exit
If a vcpu exits for a data abort with an invalid syndrome, the
expectations are that userspace has a chance to save the day if
it has requested to see such exits.

However, this is completely futile in the case of a protected VM,
as none of the state is available. In this particular case, inject
a data abort directly into the vcpu, consistent with what userspace
could do.

This also helps with pKVM, which discards all syndrome information when
forwarding data aborts that are not known to be MMIO.

Finally, document this tweak to the API.

Signed-off-by: Fuad Tabba <tabba@google.com>
Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240423150538.2103045-31-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
2024-05-01 16:48:15 +01:00
Will Deacon
4dc8c9de38 KVM: arm64: Document the KVM/arm64-specific calls in hypercalls.rst
KVM/arm64 makes use of the SMCCC "Vendor Specific Hypervisor Service
Call Range" to expose KVM-specific hypercalls to guests in a
discoverable and extensible fashion.

Document the existence of this interface and the discovery hypercall.

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240423150538.2103045-28-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
2024-05-01 16:48:14 +01:00
Will Deacon
af725804f9 KVM: arm64: Rename firmware pseudo-register documentation file
In preparation for describing the guest view of KVM/arm64 hypercalls in
hypercalls.rst, move the existing contents of the file concerning the
firmware pseudo-registers elsewhere.

Cc: Raghavendra Rao Ananta <rananta@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240423150538.2103045-27-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
2024-05-01 16:48:14 +01:00
Will Deacon
5a08146d9b KVM: arm64: Reformat/beautify PTP hypercall documentation
The PTP hypercall documentation doesn't produce the best-looking table
when formatting in HTML as all of the return value definitions end up
on the same line.

Reformat the PTP hypercall documentation to follow the formatting used
by hypercalls.rst.

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240423150538.2103045-26-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
2024-05-01 16:48:14 +01:00
Paolo Bonzini
4f5defae70 KVM: SEV: introduce KVM_SEV_INIT2 operation
The idea that no parameter would ever be necessary when enabling SEV or
SEV-ES for a VM was decidedly optimistic.  In fact, in some sense it's
already a parameter whether SEV or SEV-ES is desired.  Another possible
source of variability is the desired set of VMSA features, as that affects
the measurement of the VM's initial state and cannot be changed
arbitrarily by the hypervisor.

Create a new sub-operation for KVM_MEMORY_ENCRYPT_OP that can take a struct,
and put the new op to work by including the VMSA features as a field of the
struct.  The existing KVM_SEV_INIT and KVM_SEV_ES_INIT use the full set of
supported VMSA features for backwards compatibility.

The struct also includes the usual bells and whistles for future
extensibility: a flags field that must be zero for now, and some padding
at the end.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20240404121327.3107131-13-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-04-11 13:08:25 -04:00
Paolo Bonzini
26c44aa9e0 KVM: SEV: define VM types for SEV and SEV-ES
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20240404121327.3107131-11-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-04-11 13:08:25 -04:00
Paolo Bonzini
ac5c48027b KVM: SEV: publish supported VMSA features
Compute the set of features to be stored in the VMSA when KVM is
initialized; move it from there into kvm_sev_info when SEV is initialized,
and then into the initial VMSA.

The new variable can then be used to return the set of supported features
to userspace, via the KVM_GET_DEVICE_ATTR ioctl.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com>
Message-ID: <20240404121327.3107131-6-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-04-11 13:08:22 -04:00
Paolo Bonzini
c20722c412 Documentation: kvm/sev: clarify usage of KVM_MEMORY_ENCRYPT_OP
Explain that it operates on the VM file descriptor, and also clarify how
detection of SEV operates on old kernels predating commit 2da1ed62d5
("KVM: SVM: document KVM_MEM_ENCRYPT_OP, let userspace detect if SEV
is available").

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-03-18 19:03:53 -04:00
Paolo Bonzini
19cebbab99 Documentation: kvm/sev: separate description of firmware
The description of firmware is included part under the "SEV Key Management"
header, part under the KVM_SEV_INIT ioctl.  Put these two bits together and
and rename "SEV Key Management" to what it actually is, namely a description
of the KVM_MEMORY_ENCRYPT_OP API.

Reviewed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-03-18 19:03:52 -04:00
Paolo Bonzini
c822a075ab Guest-side KVM async #PF ABI cleanup for 6.9
Delete kvm_vcpu_pv_apf_data.enabled to fix a goof in KVM's async #PF ABI where
 the enabled field pushes the size of "struct kvm_vcpu_pv_apf_data" from 64 to
 68 bytes, i.e. beyond a single cache line.
 
 The enabled field is purely a guest-side flag that Linux-as-a-guest uses to
 track whether or not the guest has enabled async #PF support.  The actual flag
 that is passed to the host, i.e. to KVM proper, is a single bit in a synthetic
 MSR, MSR_KVM_ASYNC_PF_EN, i.e. is in a location completely unrelated to the
 shared kvm_vcpu_pv_apf_data structure.
 
 Simply drop the the field and use a dedicated guest-side per-CPU variable to
 fix the ABI, as opposed to fixing the documentation to match reality.  KVM has
 never consumed kvm_vcpu_pv_apf_data.enabled, so the odds of the ABI change
 breaking anything are extremely low.
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Merge tag 'kvm-x86-asyncpf_abi-6.9' of https://github.com/kvm-x86/linux into HEAD

Guest-side KVM async #PF ABI cleanup for 6.9

Delete kvm_vcpu_pv_apf_data.enabled to fix a goof in KVM's async #PF ABI where
the enabled field pushes the size of "struct kvm_vcpu_pv_apf_data" from 64 to
68 bytes, i.e. beyond a single cache line.

The enabled field is purely a guest-side flag that Linux-as-a-guest uses to
track whether or not the guest has enabled async #PF support.  The actual flag
that is passed to the host, i.e. to KVM proper, is a single bit in a synthetic
MSR, MSR_KVM_ASYNC_PF_EN, i.e. is in a location completely unrelated to the
shared kvm_vcpu_pv_apf_data structure.

Simply drop the the field and use a dedicated guest-side per-CPU variable to
fix the ABI, as opposed to fixing the documentation to match reality.  KVM has
never consumed kvm_vcpu_pv_apf_data.enabled, so the odds of the ABI change
breaking anything are extremely low.
2024-03-18 19:03:42 -04:00
Linus Torvalds
4f712ee0cb S390:
* Changes to FPU handling came in via the main s390 pull request
 
 * Only deliver to the guest the SCLP events that userspace has
   requested.
 
 * More virtual vs physical address fixes (only a cleanup since
   virtual and physical address spaces are currently the same).
 
 * Fix selftests undefined behavior.
 
 x86:
 
 * Fix a restriction that the guest can't program a PMU event whose
   encoding matches an architectural event that isn't included in the
   guest CPUID.  The enumeration of an architectural event only says
   that if a CPU supports an architectural event, then the event can be
   programmed *using the architectural encoding*.  The enumeration does
   NOT say anything about the encoding when the CPU doesn't report support
   the event *in general*.  It might support it, and it might support it
   using the same encoding that made it into the architectural PMU spec.
 
 * Fix a variety of bugs in KVM's emulation of RDPMC (more details on
   individual commits) and add a selftest to verify KVM correctly emulates
   RDMPC, counter availability, and a variety of other PMC-related
   behaviors that depend on guest CPUID and therefore are easier to
   validate with selftests than with custom guests (aka kvm-unit-tests).
 
 * Zero out PMU state on AMD if the virtual PMU is disabled, it does not
   cause any bug but it wastes time in various cases where KVM would check
   if a PMC event needs to be synthesized.
 
 * Optimize triggering of emulated events, with a nice ~10% performance
   improvement in VM-Exit microbenchmarks when a vPMU is exposed to the
   guest.
 
 * Tighten the check for "PMI in guest" to reduce false positives if an NMI
   arrives in the host while KVM is handling an IRQ VM-Exit.
 
 * Fix a bug where KVM would report stale/bogus exit qualification information
   when exiting to userspace with an internal error exit code.
 
 * Add a VMX flag in /proc/cpuinfo to report 5-level EPT support.
 
 * Rework TDP MMU root unload, free, and alloc to run with mmu_lock held for
   read, e.g. to avoid serializing vCPUs when userspace deletes a memslot.
 
 * Tear down TDP MMU page tables at 4KiB granularity (used to be 1GiB).  KVM
   doesn't support yielding in the middle of processing a zap, and 1GiB
   granularity resulted in multi-millisecond lags that are quite impolite
   for CONFIG_PREEMPT kernels.
 
 * Allocate write-tracking metadata on-demand to avoid the memory overhead when
   a kernel is built with i915 virtualization support but the workloads use
   neither shadow paging nor i915 virtualization.
 
 * Explicitly initialize a variety of on-stack variables in the emulator that
   triggered KMSAN false positives.
 
 * Fix the debugregs ABI for 32-bit KVM.
 
 * Rework the "force immediate exit" code so that vendor code ultimately decides
   how and when to force the exit, which allowed some optimization for both
   Intel and AMD.
 
 * Fix a long-standing bug where kvm_has_noapic_vcpu could be left elevated if
   vCPU creation ultimately failed, causing extra unnecessary work.
 
 * Cleanup the logic for checking if the currently loaded vCPU is in-kernel.
 
 * Harden against underflowing the active mmu_notifier invalidation
   count, so that "bad" invalidations (usually due to bugs elsehwere in the
   kernel) are detected earlier and are less likely to hang the kernel.
 
 x86 Xen emulation:
 
 * Overlay pages can now be cached based on host virtual address,
   instead of guest physical addresses.  This removes the need to
   reconfigure and invalidate the cache if the guest changes the
   gpa but the underlying host virtual address remains the same.
 
 * When possible, use a single host TSC value when computing the deadline for
   Xen timers in order to improve the accuracy of the timer emulation.
 
 * Inject pending upcall events when the vCPU software-enables its APIC to fix
   a bug where an upcall can be lost (and to follow Xen's behavior).
 
 * Fall back to the slow path instead of warning if "fast" IRQ delivery of Xen
   events fails, e.g. if the guest has aliased xAPIC IDs.
 
 RISC-V:
 
 * Support exception and interrupt handling in selftests
 
 * New self test for RISC-V architectural timer (Sstc extension)
 
 * New extension support (Ztso, Zacas)
 
 * Support userspace emulation of random number seed CSRs.
 
 ARM:
 
 * Infrastructure for building KVM's trap configuration based on the
   architectural features (or lack thereof) advertised in the VM's ID
   registers
 
 * Support for mapping vfio-pci BARs as Normal-NC (vaguely similar to
   x86's WC) at stage-2, improving the performance of interacting with
   assigned devices that can tolerate it
 
 * Conversion of KVM's representation of LPIs to an xarray, utilized to
   address serialization some of the serialization on the LPI injection
   path
 
 * Support for _architectural_ VHE-only systems, advertised through the
   absence of FEAT_E2H0 in the CPU's ID register
 
 * Miscellaneous cleanups, fixes, and spelling corrections to KVM and
   selftests
 
 LoongArch:
 
 * Set reserved bits as zero in CPUCFG.
 
 * Start SW timer only when vcpu is blocking.
 
 * Do not restart SW timer when it is expired.
 
 * Remove unnecessary CSR register saving during enter guest.
 
 * Misc cleanups and fixes as usual.
 
 Generic:
 
 * cleanup Kconfig by removing CONFIG_HAVE_KVM, which was basically always
   true on all architectures except MIPS (where Kconfig determines the
   available depending on CPU capabilities).  It is replaced either by
   an architecture-dependent symbol for MIPS, and IS_ENABLED(CONFIG_KVM)
   everywhere else.
 
 * Factor common "select" statements in common code instead of requiring
   each architecture to specify it
 
 * Remove thoroughly obsolete APIs from the uapi headers.
 
 * Move architecture-dependent stuff to uapi/asm/kvm.h
 
 * Always flush the async page fault workqueue when a work item is being
   removed, especially during vCPU destruction, to ensure that there are no
   workers running in KVM code when all references to KVM-the-module are gone,
   i.e. to prevent a very unlikely use-after-free if kvm.ko is unloaded.
 
 * Grab a reference to the VM's mm_struct in the async #PF worker itself instead
   of gifting the worker a reference, so that there's no need to remember
   to *conditionally* clean up after the worker.
 
 Selftests:
 
 * Reduce boilerplate especially when utilize selftest TAP infrastructure.
 
 * Add basic smoke tests for SEV and SEV-ES, along with a pile of library
   support for handling private/encrypted/protected memory.
 
 * Fix benign bugs where tests neglect to close() guest_memfd files.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm updates from Paolo Bonzini:
 "S390:

   - Changes to FPU handling came in via the main s390 pull request

   - Only deliver to the guest the SCLP events that userspace has
     requested

   - More virtual vs physical address fixes (only a cleanup since
     virtual and physical address spaces are currently the same)

   - Fix selftests undefined behavior

  x86:

   - Fix a restriction that the guest can't program a PMU event whose
     encoding matches an architectural event that isn't included in the
     guest CPUID. The enumeration of an architectural event only says
     that if a CPU supports an architectural event, then the event can
     be programmed *using the architectural encoding*. The enumeration
     does NOT say anything about the encoding when the CPU doesn't
     report support the event *in general*. It might support it, and it
     might support it using the same encoding that made it into the
     architectural PMU spec

   - Fix a variety of bugs in KVM's emulation of RDPMC (more details on
     individual commits) and add a selftest to verify KVM correctly
     emulates RDMPC, counter availability, and a variety of other
     PMC-related behaviors that depend on guest CPUID and therefore are
     easier to validate with selftests than with custom guests (aka
     kvm-unit-tests)

   - Zero out PMU state on AMD if the virtual PMU is disabled, it does
     not cause any bug but it wastes time in various cases where KVM
     would check if a PMC event needs to be synthesized

   - Optimize triggering of emulated events, with a nice ~10%
     performance improvement in VM-Exit microbenchmarks when a vPMU is
     exposed to the guest

   - Tighten the check for "PMI in guest" to reduce false positives if
     an NMI arrives in the host while KVM is handling an IRQ VM-Exit

   - Fix a bug where KVM would report stale/bogus exit qualification
     information when exiting to userspace with an internal error exit
     code

   - Add a VMX flag in /proc/cpuinfo to report 5-level EPT support

   - Rework TDP MMU root unload, free, and alloc to run with mmu_lock
     held for read, e.g. to avoid serializing vCPUs when userspace
     deletes a memslot

   - Tear down TDP MMU page tables at 4KiB granularity (used to be
     1GiB). KVM doesn't support yielding in the middle of processing a
     zap, and 1GiB granularity resulted in multi-millisecond lags that
     are quite impolite for CONFIG_PREEMPT kernels

   - Allocate write-tracking metadata on-demand to avoid the memory
     overhead when a kernel is built with i915 virtualization support
     but the workloads use neither shadow paging nor i915 virtualization

   - Explicitly initialize a variety of on-stack variables in the
     emulator that triggered KMSAN false positives

   - Fix the debugregs ABI for 32-bit KVM

   - Rework the "force immediate exit" code so that vendor code
     ultimately decides how and when to force the exit, which allowed
     some optimization for both Intel and AMD

   - Fix a long-standing bug where kvm_has_noapic_vcpu could be left
     elevated if vCPU creation ultimately failed, causing extra
     unnecessary work

   - Cleanup the logic for checking if the currently loaded vCPU is
     in-kernel

   - Harden against underflowing the active mmu_notifier invalidation
     count, so that "bad" invalidations (usually due to bugs elsehwere
     in the kernel) are detected earlier and are less likely to hang the
     kernel

  x86 Xen emulation:

   - Overlay pages can now be cached based on host virtual address,
     instead of guest physical addresses. This removes the need to
     reconfigure and invalidate the cache if the guest changes the gpa
     but the underlying host virtual address remains the same

   - When possible, use a single host TSC value when computing the
     deadline for Xen timers in order to improve the accuracy of the
     timer emulation

   - Inject pending upcall events when the vCPU software-enables its
     APIC to fix a bug where an upcall can be lost (and to follow Xen's
     behavior)

   - Fall back to the slow path instead of warning if "fast" IRQ
     delivery of Xen events fails, e.g. if the guest has aliased xAPIC
     IDs

  RISC-V:

   - Support exception and interrupt handling in selftests

   - New self test for RISC-V architectural timer (Sstc extension)

   - New extension support (Ztso, Zacas)

   - Support userspace emulation of random number seed CSRs

  ARM:

   - Infrastructure for building KVM's trap configuration based on the
     architectural features (or lack thereof) advertised in the VM's ID
     registers

   - Support for mapping vfio-pci BARs as Normal-NC (vaguely similar to
     x86's WC) at stage-2, improving the performance of interacting with
     assigned devices that can tolerate it

   - Conversion of KVM's representation of LPIs to an xarray, utilized
     to address serialization some of the serialization on the LPI
     injection path

   - Support for _architectural_ VHE-only systems, advertised through
     the absence of FEAT_E2H0 in the CPU's ID register

   - Miscellaneous cleanups, fixes, and spelling corrections to KVM and
     selftests

  LoongArch:

   - Set reserved bits as zero in CPUCFG

   - Start SW timer only when vcpu is blocking

   - Do not restart SW timer when it is expired

   - Remove unnecessary CSR register saving during enter guest

   - Misc cleanups and fixes as usual

  Generic:

   - Clean up Kconfig by removing CONFIG_HAVE_KVM, which was basically
     always true on all architectures except MIPS (where Kconfig
     determines the available depending on CPU capabilities). It is
     replaced either by an architecture-dependent symbol for MIPS, and
     IS_ENABLED(CONFIG_KVM) everywhere else

   - Factor common "select" statements in common code instead of
     requiring each architecture to specify it

   - Remove thoroughly obsolete APIs from the uapi headers

   - Move architecture-dependent stuff to uapi/asm/kvm.h

   - Always flush the async page fault workqueue when a work item is
     being removed, especially during vCPU destruction, to ensure that
     there are no workers running in KVM code when all references to
     KVM-the-module are gone, i.e. to prevent a very unlikely
     use-after-free if kvm.ko is unloaded

   - Grab a reference to the VM's mm_struct in the async #PF worker
     itself instead of gifting the worker a reference, so that there's
     no need to remember to *conditionally* clean up after the worker

  Selftests:

   - Reduce boilerplate especially when utilize selftest TAP
     infrastructure

   - Add basic smoke tests for SEV and SEV-ES, along with a pile of
     library support for handling private/encrypted/protected memory

   - Fix benign bugs where tests neglect to close() guest_memfd files"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (246 commits)
  selftests: kvm: remove meaningless assignments in Makefiles
  KVM: riscv: selftests: Add Zacas extension to get-reg-list test
  RISC-V: KVM: Allow Zacas extension for Guest/VM
  KVM: riscv: selftests: Add Ztso extension to get-reg-list test
  RISC-V: KVM: Allow Ztso extension for Guest/VM
  RISC-V: KVM: Forward SEED CSR access to user space
  KVM: riscv: selftests: Add sstc timer test
  KVM: riscv: selftests: Change vcpu_has_ext to a common function
  KVM: riscv: selftests: Add guest helper to get vcpu id
  KVM: riscv: selftests: Add exception handling support
  LoongArch: KVM: Remove unnecessary CSR register saving during enter guest
  LoongArch: KVM: Do not restart SW timer when it is expired
  LoongArch: KVM: Start SW timer only when vcpu is blocking
  LoongArch: KVM: Set reserved bits as zero in CPUCFG
  KVM: selftests: Explicitly close guest_memfd files in some gmem tests
  KVM: x86/xen: fix recursive deadlock in timer injection
  KVM: pfncache: simplify locking and make more self-contained
  KVM: x86/xen: remove WARN_ON_ONCE() with false positives in evtchn delivery
  KVM: x86/xen: inject vCPU upcall vector when local APIC is enabled
  KVM: x86/xen: improve accuracy of Xen timers
  ...
2024-03-15 13:03:13 -07:00
Linus Torvalds
38b334fc76 - Add the x86 part of the SEV-SNP host support. This will allow the
kernel to be used as a KVM hypervisor capable of running SNP (Secure
   Nested Paging) guests. Roughly speaking, SEV-SNP is the ultimate goal
   of the AMD confidential computing side, providing the most
   comprehensive confidential computing environment up to date.
 
   This is the x86 part and there is a KVM part which did not get ready
   in time for the merge window so latter will be forthcoming in the next
   cycle.
 
 - Rework the early code's position-dependent SEV variable references in
   order to allow building the kernel with clang and -fPIE/-fPIC and
   -mcmodel=kernel
 
 - The usual set of fixes, cleanups and improvements all over the place
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Merge tag 'x86_sev_for_v6.9_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 SEV updates from Borislav Petkov:

 - Add the x86 part of the SEV-SNP host support.

   This will allow the kernel to be used as a KVM hypervisor capable of
   running SNP (Secure Nested Paging) guests. Roughly speaking, SEV-SNP
   is the ultimate goal of the AMD confidential computing side,
   providing the most comprehensive confidential computing environment
   up to date.

   This is the x86 part and there is a KVM part which did not get ready
   in time for the merge window so latter will be forthcoming in the
   next cycle.

 - Rework the early code's position-dependent SEV variable references in
   order to allow building the kernel with clang and -fPIE/-fPIC and
   -mcmodel=kernel

 - The usual set of fixes, cleanups and improvements all over the place

* tag 'x86_sev_for_v6.9_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
  x86/sev: Disable KMSAN for memory encryption TUs
  x86/sev: Dump SEV_STATUS
  crypto: ccp - Have it depend on AMD_IOMMU
  iommu/amd: Fix failure return from snp_lookup_rmpentry()
  x86/sev: Fix position dependent variable references in startup code
  crypto: ccp: Make snp_range_list static
  x86/Kconfig: Remove CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
  Documentation: virt: Fix up pre-formatted text block for SEV ioctls
  crypto: ccp: Add the SNP_SET_CONFIG command
  crypto: ccp: Add the SNP_COMMIT command
  crypto: ccp: Add the SNP_PLATFORM_STATUS command
  x86/cpufeatures: Enable/unmask SEV-SNP CPU feature
  KVM: SEV: Make AVIC backing, VMSA and VMCB memory allocation SNP safe
  crypto: ccp: Add panic notifier for SEV/SNP firmware shutdown on kdump
  iommu/amd: Clean up RMP entries for IOMMU pages during SNP shutdown
  crypto: ccp: Handle legacy SEV commands when SNP is enabled
  crypto: ccp: Handle non-volatile INIT_EX data when SNP is enabled
  crypto: ccp: Handle the legacy TMR allocation when SNP is enabled
  x86/sev: Introduce an SNP leaked pages list
  crypto: ccp: Provide an API to issue SEV and SNP commands
  ...
2024-03-11 17:44:11 -07:00
Paolo Bonzini
e9a2bba476 KVM Xen and pfncache changes for 6.9:
- Rip out the half-baked support for using gfn_to_pfn caches to manage pages
    that are "mapped" into guests via physical addresses.
 
  - Add support for using gfn_to_pfn caches with only a host virtual address,
    i.e. to bypass the "gfn" stage of the cache.  The primary use case is
    overlay pages, where the guest may change the gfn used to reference the
    overlay page, but the backing hva+pfn remains the same.
 
  - Add an ioctl() to allow mapping Xen's shared_info page using an hva instead
    of a gpa, so that userspace doesn't need to reconfigure and invalidate the
    cache/mapping if the guest changes the gpa (but userspace keeps the resolved
    hva the same).
 
  - When possible, use a single host TSC value when computing the deadline for
    Xen timers in order to improve the accuracy of the timer emulation.
 
  - Inject pending upcall events when the vCPU software-enables its APIC to fix
    a bug where an upcall can be lost (and to follow Xen's behavior).
 
  - Fall back to the slow path instead of warning if "fast" IRQ delivery of Xen
    events fails, e.g. if the guest has aliased xAPIC IDs.
 
  - Extend gfn_to_pfn_cache's mutex to cover (de)activation (in addition to
    refresh), and drop a now-redundant acquisition of xen_lock (that was
    protecting the shared_info cache) to fix a deadlock due to recursively
    acquiring xen_lock.
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Merge tag 'kvm-x86-xen-6.9' of https://github.com/kvm-x86/linux into HEAD

KVM Xen and pfncache changes for 6.9:

 - Rip out the half-baked support for using gfn_to_pfn caches to manage pages
   that are "mapped" into guests via physical addresses.

 - Add support for using gfn_to_pfn caches with only a host virtual address,
   i.e. to bypass the "gfn" stage of the cache.  The primary use case is
   overlay pages, where the guest may change the gfn used to reference the
   overlay page, but the backing hva+pfn remains the same.

 - Add an ioctl() to allow mapping Xen's shared_info page using an hva instead
   of a gpa, so that userspace doesn't need to reconfigure and invalidate the
   cache/mapping if the guest changes the gpa (but userspace keeps the resolved
   hva the same).

 - When possible, use a single host TSC value when computing the deadline for
   Xen timers in order to improve the accuracy of the timer emulation.

 - Inject pending upcall events when the vCPU software-enables its APIC to fix
   a bug where an upcall can be lost (and to follow Xen's behavior).

 - Fall back to the slow path instead of warning if "fast" IRQ delivery of Xen
   events fails, e.g. if the guest has aliased xAPIC IDs.

 - Extend gfn_to_pfn_cache's mutex to cover (de)activation (in addition to
   refresh), and drop a now-redundant acquisition of xen_lock (that was
   protecting the shared_info cache) to fix a deadlock due to recursively
   acquiring xen_lock.
2024-03-11 10:42:55 -04:00
Linus Torvalds
137e0ec05a KVM GUEST_MEMFD fixes for 6.8:
- Make KVM_MEM_GUEST_MEMFD mutually exclusive with KVM_MEM_READONLY to
   avoid creating an inconsistent ABI (KVM_MEM_GUEST_MEMFD is not writable
   from userspace, so there would be no way to write to a read-only
   guest_memfd).
 
 - Update documentation for KVM_SW_PROTECTED_VM to make it abundantly
   clear that such VMs are purely for development and testing.
 
 - Limit KVM_SW_PROTECTED_VM guests to the TDP MMU, as the long term plan
   is to support confidential VMs with deterministic private memory (SNP
   and TDX) only in the TDP MMU.
 
 - Fix a bug in a GUEST_MEMFD dirty logging test that caused false passes.
 
 x86 fixes:
 
 - Fix missing marking of a guest page as dirty when emulating an atomic access.
 
 - Check for mmu_notifier invalidation events before faulting in the pfn,
   and before acquiring mmu_lock, to avoid unnecessary work and lock
   contention with preemptible kernels (including CONFIG_PREEMPT_DYNAMIC
   in non-preemptible mode).
 
 - Disable AMD DebugSwap by default, it breaks VMSA signing and will be
   re-enabled with a better VM creation API in 6.10.
 
 - Do the cache flush of converted pages in svm_register_enc_region() before
   dropping kvm->lock, to avoid a race with unregistering of the same region
   and the consequent use-after-free issue.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:
 "KVM GUEST_MEMFD fixes for 6.8:

   - Make KVM_MEM_GUEST_MEMFD mutually exclusive with KVM_MEM_READONLY
     to avoid creating an inconsistent ABI (KVM_MEM_GUEST_MEMFD is not
     writable from userspace, so there would be no way to write to a
     read-only guest_memfd).

   - Update documentation for KVM_SW_PROTECTED_VM to make it abundantly
     clear that such VMs are purely for development and testing.

   - Limit KVM_SW_PROTECTED_VM guests to the TDP MMU, as the long term
     plan is to support confidential VMs with deterministic private
     memory (SNP and TDX) only in the TDP MMU.

   - Fix a bug in a GUEST_MEMFD dirty logging test that caused false
     passes.

  x86 fixes:

   - Fix missing marking of a guest page as dirty when emulating an
     atomic access.

   - Check for mmu_notifier invalidation events before faulting in the
     pfn, and before acquiring mmu_lock, to avoid unnecessary work and
     lock contention with preemptible kernels (including
     CONFIG_PREEMPT_DYNAMIC in non-preemptible mode).

   - Disable AMD DebugSwap by default, it breaks VMSA signing and will
     be re-enabled with a better VM creation API in 6.10.

   - Do the cache flush of converted pages in svm_register_enc_region()
     before dropping kvm->lock, to avoid a race with unregistering of
     the same region and the consequent use-after-free issue"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  SEV: disable SEV-ES DebugSwap by default
  KVM: x86/mmu: Retry fault before acquiring mmu_lock if mapping is changing
  KVM: SVM: Flush pages under kvm->lock to fix UAF in svm_register_enc_region()
  KVM: selftests: Add a testcase to verify GUEST_MEMFD and READONLY are exclusive
  KVM: selftests: Create GUEST_MEMFD for relevant invalid flags testcases
  KVM: x86/mmu: Restrict KVM_SW_PROTECTED_VM to the TDP MMU
  KVM: x86: Update KVM_SW_PROTECTED_VM docs to make it clear they're a WIP
  KVM: Make KVM_MEM_GUEST_MEMFD mutually exclusive with KVM_MEM_READONLY
  KVM: x86: Mark target gfn of emulated atomic instruction as dirty
2024-03-10 09:27:39 -07:00
Michael Kelley
04ed680e76 Documentation: hyperv: Add overview of PCI pass-thru device support
Add documentation topic for PCI pass-thru devices in Linux guests
on Hyper-V and for the associated PCI controller driver (pci-hyperv.c).

Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com>
Link: https://lore.kernel.org/r/20240222200710.305259-1-mhklinux@outlook.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20240222200710.305259-1-mhklinux@outlook.com>
2024-03-01 08:29:49 +00:00
Sean Christopherson
422692098c KVM: x86: Update KVM_SW_PROTECTED_VM docs to make it clear they're a WIP
Rewrite the help message for KVM_SW_PROTECTED_VM to make it clear that
software-protected VMs are a development and testing vehicle for
guest_memfd(), and that attempting to use KVM_SW_PROTECTED_VM for anything
remotely resembling a "real" VM will fail.  E.g. any memory accesses from
KVM will incorrectly access shared memory, nested TDP is wildly broken,
and so on and so forth.

Update KVM's API documentation with similar warnings to discourage anyone
from attempting to run anything but selftests with KVM_X86_SW_PROTECTED_VM.

Fixes: 89ea60c2c7 ("KVM: x86: Add support for "protected VMs" that can utilize private memory")
Link: https://lore.kernel.org/r/20240222190612.2942589-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-02-22 17:07:06 -08:00
Paul Durrant
3991f35805 KVM: x86/xen: allow vcpu_info to be mapped by fixed HVA
If the guest does not explicitly set the GPA of vcpu_info structure in
memory then, for guests with 32 vCPUs or fewer, the vcpu_info embedded
in the shared_info page may be used. As described in a previous commit,
the shared_info page is an overlay at a fixed HVA within the VMM, so in
this case it also more optimal to activate the vcpu_info cache with a
fixed HVA to avoid unnecessary invalidation if the guest memory layout
is modified.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-14-paul@xen.org
[sean: use kvm_gpc_is_{gpa,hva}_active()]
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-02-22 07:01:17 -08:00
Paul Durrant
b9220d3279 KVM: x86/xen: allow shared_info to be mapped by fixed HVA
The shared_info page is not guest memory as such. It is a dedicated page
allocated by the VMM and overlaid onto guest memory in a GFN chosen by the
guest and specified in the XENMEM_add_to_physmap hypercall. The guest may
even request that shared_info be moved from one GFN to another by
re-issuing that hypercall, but the HVA is never going to change.

Because the shared_info page is an overlay the memory slots need to be
updated in response to the hypercall. However, memory slot adjustment is
not atomic and, whilst all vCPUs are paused, there is still the possibility
that events may be delivered (which requires the shared_info page to be
updated) whilst the shared_info GPA is absent. The HVA is never absent
though, so it makes much more sense to use that as the basis for the
kernel's mapping.

Hence add a new KVM_XEN_ATTR_TYPE_SHARED_INFO_HVA attribute type for this
purpose and a KVM_XEN_HVM_CONFIG_SHARED_INFO_HVA flag to advertize its
availability. Don't actually advertize it yet though. That will be done in
a subsequent patch, which will also add tests for the new attribute type.

Also update the KVM API documentation with the new attribute and also fix
it up to consistently refer to 'shared_info' (with the underscore).

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-13-paul@xen.org
[sean: store "hva" as a user pointer, use kvm_gpc_is_{gpa,hva}_active()]
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-02-22 07:00:52 -08:00
Xiaoyao Li
df01f0a116 KVM: x86: Improve documentation of MSR_KVM_ASYNC_PF_EN
Fix some incorrect statement of MSR_KVM_ASYNC_PF_EN documentation and
state clearly the token in 'struct kvm_vcpu_pv_apf_data' of 'page ready'
event is matchted with the token in CR2 in 'page not present' event.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20231025055914.1201792-3-xiaoyao.li@intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-02-06 10:59:52 -08:00
Xiaoyao Li
ccb2280ec2 x86/kvm: Use separate percpu variable to track the enabling of asyncpf
Refer to commit fd10cde929 ("KVM paravirt: Add async PF initialization
to PV guest") and commit 344d9588a9 ("KVM: Add PV MSR to enable
asynchronous page faults delivery"). It turns out that at the time when
asyncpf was introduced, the purpose was defining the shared PV data 'struct
kvm_vcpu_pv_apf_data' with the size of 64 bytes. However, it made a mistake
and defined the size to 68 bytes, which failed to make fit in a cache line
and made the code inconsistent with the documentation.

Below justification quoted from Sean[*]

  KVM (the host side) has *never* read kvm_vcpu_pv_apf_data.enabled, and
  the documentation clearly states that enabling is based solely on the
  bit in the synthetic MSR.

  So rather than update the documentation, fix the goof by removing the
  enabled filed and use the separate percpu variable instread.
  KVM-as-a-host obviously doesn't enforce anything or consume the size,
  and changing the header will only affect guests that are rebuilt against
  the new header, so there's no chance of ABI breakage between KVM and its
  guests. The only possible breakage is if some other hypervisor is
  emulating KVM's async #PF (LOL) and relies on the guest to set
  kvm_vcpu_pv_apf_data.enabled. But (a) I highly doubt such a hypervisor
  exists, (b) that would arguably be a violation of KVM's "spec", and
  (c) the worst case scenario is that the guest would simply lose async
  #PF functionality.

[*] https://lore.kernel.org/all/ZS7ERnnRqs8Fl0ZF@google.com/T/#u

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20231025055914.1201792-2-xiaoyao.li@intel.com
[sean: use true/false instead of 1/0 for booleans]
Signed-off-by: Sean Christopherson <seanjc@google.com>
2024-02-06 10:58:56 -08:00
Michael Roth
1bfca8d280 Documentation: virt: Fix up pre-formatted text block for SEV ioctls
A missing newline after "::" resulted in the htmldocs build failing to
recognize the start of a pre-formatted block of text, resulting in

  kernel/linux/Documentation/virt/coco/sev-guest.rst:75: WARNING: Inline emphasis start-string without end-string.
  kernel/linux/Documentation/virt/coco/sev-guest.rst:78: WARNING: Inline emphasis start-string without end-string.
  kernel/linux/Documentation/virt/coco/sev-guest.rst:81: WARNING: Inline emphasis start-string without end-string.
  kernel/linux/Documentation/virt/coco/sev-guest.rst:83: WARNING: Definition list ends without a blank line; unexpected unindent.

Fix it.

Fixes: f5db8841eb ("crypto: ccp: Add the SNP_PLATFORM_STATUS command")
Closes: https://lore.kernel.org/linux-next/20240202145932.31c62fd6@canb.auug.org.au/
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240202160544.2297320-1-michael.roth@amd.com
2024-02-02 17:21:22 +01:00
Brijesh Singh
cb645fe478 crypto: ccp: Add the SNP_SET_CONFIG command
The SEV-SNP firmware provides the SNP_CONFIG command used to set various
system-wide configuration values for SNP guests, such as the reported
TCB version used when signing guest attestation reports. Add an
interface to set this via userspace.

  [ mdr: Squash in doc patch from Dionna, drop extended request/
    certificate handling and simplify this to a simple wrapper around
    SNP_CONFIG fw cmd. ]

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Co-developed-by: Alexey Kardashevskiy <aik@amd.com>
Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
Co-developed-by: Dionna Glaze <dionnaglaze@google.com>
Signed-off-by: Dionna Glaze <dionnaglaze@google.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240126041126.1927228-26-michael.roth@amd.com
2024-01-29 20:34:19 +01:00
Tom Lendacky
fad133c79a crypto: ccp: Add the SNP_COMMIT command
The SNP_COMMIT command is used to commit the currently installed version
of the SEV firmware. Once committed, the firmware cannot be replaced
with a previous firmware version (cannot be rolled back). This command
will also update the reported TCB to match that of the currently
installed firmware.

  [ mdr: Note the reported TCB update in the documentation/commit. ]

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240126041126.1927228-25-michael.roth@amd.com
2024-01-29 20:34:19 +01:00
Brijesh Singh
f5db8841eb crypto: ccp: Add the SNP_PLATFORM_STATUS command
This command is used to query the SNP platform status. See the SEV-SNP
spec for more details.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240126041126.1927228-24-michael.roth@amd.com
2024-01-29 20:34:19 +01:00
Paolo Bonzini
7f26fea9bc KVM x86 MMU changes for 6.8:
- Fix a relatively benign off-by-one error when splitting huge pages during
    CLEAR_DIRTY_LOG.
 
  - Fix a bug where KVM could incorrectly test-and-clear dirty bits in non-leaf
    TDP MMU SPTEs if a racing thread replaces a huge SPTE with a non-huge SPTE.
 
  - Relax the TDP MMU's lockdep assertions related to holding mmu_lock for read
    versus write so that KVM doesn't pass "bool shared" all over the place just
    to have precise assertions in paths that don't actually care about whether
    the caller is a reader or a writer.
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Merge tag 'kvm-x86-mmu-6.8' of https://github.com/kvm-x86/linux into HEAD

KVM x86 MMU changes for 6.8:

 - Fix a relatively benign off-by-one error when splitting huge pages during
   CLEAR_DIRTY_LOG.

 - Fix a bug where KVM could incorrectly test-and-clear dirty bits in non-leaf
   TDP MMU SPTEs if a racing thread replaces a huge SPTE with a non-huge SPTE.

 - Relax the TDP MMU's lockdep assertions related to holding mmu_lock for read
   versus write so that KVM doesn't pass "bool shared" all over the place just
   to have precise assertions in paths that don't actually care about whether
   the caller is a reader or a writer.
2024-01-08 08:10:32 -05:00
Paolo Bonzini
3115d2de39 KVM Xen change for 6.8:
To workaround Xen guests that don't expect Xen PV clocks to be marked as being
 based on a stable TSC, add a Xen config knob to allow userspace to opt out of
 KVM setting the "TSC stable" bit in Xen PV clocks.  Note, the "TSC stable" bit
 was added to the PVCLOCK ABI by KVM without an ack from Xen, i.e. KVM isn't
 entirely blameless for the buggy guest behavior.
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Merge tag 'kvm-x86-xen-6.8' of https://github.com/kvm-x86/linux into HEAD

KVM Xen change for 6.8:

To workaround Xen guests that don't expect Xen PV clocks to be marked as being
based on a stable TSC, add a Xen config knob to allow userspace to opt out of
KVM setting the "TSC stable" bit in Xen PV clocks.  Note, the "TSC stable" bit
was added to the PVCLOCK ABI by KVM without an ack from Xen, i.e. KVM isn't
entirely blameless for the buggy guest behavior.
2024-01-08 08:10:20 -05:00
Paolo Bonzini
a5d3df8ae1 KVM: remove deprecated UAPIs
The deprecated interfaces were removed 15 years ago.  KVM's
device assignment was deprecated in 4.2 and removed 6.5 years
ago; the only interest might be in compiling ancient versions
of QEMU, but QEMU has been using its own imported copy of the
kernel headers since June 2011.  So again we go into archaeology
territory; just remove the cruft.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-12-08 15:43:33 -05:00
Paul Durrant
6d72283526 KVM x86/xen: add an override for PVCLOCK_TSC_STABLE_BIT
Unless explicitly told to do so (by passing 'clocksource=tsc' and
'tsc=stable:socket', and then jumping through some hoops concerning
potential CPU hotplug) Xen will never use TSC as its clocksource.
Hence, by default, a Xen guest will not see PVCLOCK_TSC_STABLE_BIT set
in either the primary or secondary pvclock memory areas. This has
led to bugs in some guest kernels which only become evident if
PVCLOCK_TSC_STABLE_BIT *is* set in the pvclocks. Hence, to support
such guests, give the VMM a new Xen HVM config flag to tell KVM to
forcibly clear the bit in the Xen pvclocks.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20231102162128.2353459-1-paul@xen.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-12-07 15:52:57 -08:00
Paolo Bonzini
250ce1b4d2 KVM: x86/mmu: always take tdp_mmu_pages_lock
It is cheap to take tdp_mmu_pages_lock in all write-side critical sections.
We already do it all the time when zapping with read_lock(), so it is not
a problem to do it from the kvm_tdp_mmu_zap_all() path (aka
kvm_arch_flush_shadow_all(), aka VM destruction and MMU notifier release).

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20231125083400.1399197-4-pbonzini@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-12-01 07:52:08 -08:00
Sean Christopherson
89ea60c2c7 KVM: x86: Add support for "protected VMs" that can utilize private memory
Add a new x86 VM type, KVM_X86_SW_PROTECTED_VM, to serve as a development
and testing vehicle for Confidential (CoCo) VMs, and potentially to even
become a "real" product in the distant future, e.g. a la pKVM.

The private memory support in KVM x86 is aimed at AMD's SEV-SNP and
Intel's TDX, but those technologies are extremely complex (understatement),
difficult to debug, don't support running as nested guests, and require
hardware that's isn't universally accessible.  I.e. relying SEV-SNP or TDX
for maintaining guest private memory isn't a realistic option.

At the very least, KVM_X86_SW_PROTECTED_VM will enable a variety of
selftests for guest_memfd and private memory support without requiring
unique hardware.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20231027182217.3615211-24-seanjc@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-11-14 08:01:05 -05:00
Chao Peng
8dd2eee9d5 KVM: x86/mmu: Handle page fault for private memory
Add support for resolving page faults on guest private memory for VMs
that differentiate between "shared" and "private" memory.  For such VMs,
KVM_MEM_GUEST_MEMFD memslots can include both fd-based private memory and
hva-based shared memory, and KVM needs to map in the "correct" variant,
i.e. KVM needs to map the gfn shared/private as appropriate based on the
current state of the gfn's KVM_MEMORY_ATTRIBUTE_PRIVATE flag.

For AMD's SEV-SNP and Intel's TDX, the guest effectively gets to request
shared vs. private via a bit in the guest page tables, i.e. what the guest
wants may conflict with the current memory attributes.  To support such
"implicit" conversion requests, exit to user with KVM_EXIT_MEMORY_FAULT
to forward the request to userspace.  Add a new flag for memory faults,
KVM_MEMORY_EXIT_FLAG_PRIVATE, to communicate whether the guest wants to
map memory as shared vs. private.

Like KVM_MEMORY_ATTRIBUTE_PRIVATE, use bit 3 for flagging private memory
so that KVM can use bits 0-2 for capturing RWX behavior if/when userspace
needs such information, e.g. a likely user of KVM_EXIT_MEMORY_FAULT is to
exit on missing mappings when handling guest page fault VM-Exits.  In
that case, userspace will want to know RWX information in order to
correctly/precisely resolve the fault.

Note, private memory *must* be backed by guest_memfd, i.e. shared mappings
always come from the host userspace page tables, and private mappings
always come from a guest_memfd instance.

Co-developed-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Message-Id: <20231027182217.3615211-21-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-11-14 08:01:04 -05:00
Sean Christopherson
a7800aa80e KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory
Introduce an ioctl(), KVM_CREATE_GUEST_MEMFD, to allow creating file-based
memory that is tied to a specific KVM virtual machine and whose primary
purpose is to serve guest memory.

A guest-first memory subsystem allows for optimizations and enhancements
that are kludgy or outright infeasible to implement/support in a generic
memory subsystem.  With guest_memfd, guest protections and mapping sizes
are fully decoupled from host userspace mappings.   E.g. KVM currently
doesn't support mapping memory as writable in the guest without it also
being writable in host userspace, as KVM's ABI uses VMA protections to
define the allow guest protection.  Userspace can fudge this by
establishing two mappings, a writable mapping for the guest and readable
one for itself, but that’s suboptimal on multiple fronts.

Similarly, KVM currently requires the guest mapping size to be a strict
subset of the host userspace mapping size, e.g. KVM doesn’t support
creating a 1GiB guest mapping unless userspace also has a 1GiB guest
mapping.  Decoupling the mappings sizes would allow userspace to precisely
map only what is needed without impacting guest performance, e.g. to
harden against unintentional accesses to guest memory.

Decoupling guest and userspace mappings may also allow for a cleaner
alternative to high-granularity mappings for HugeTLB, which has reached a
bit of an impasse and is unlikely to ever be merged.

A guest-first memory subsystem also provides clearer line of sight to
things like a dedicated memory pool (for slice-of-hardware VMs) and
elimination of "struct page" (for offload setups where userspace _never_
needs to mmap() guest memory).

More immediately, being able to map memory into KVM guests without mapping
said memory into the host is critical for Confidential VMs (CoCo VMs), the
initial use case for guest_memfd.  While AMD's SEV and Intel's TDX prevent
untrusted software from reading guest private data by encrypting guest
memory with a key that isn't usable by the untrusted host, projects such
as Protected KVM (pKVM) provide confidentiality and integrity *without*
relying on memory encryption.  And with SEV-SNP and TDX, accessing guest
private memory can be fatal to the host, i.e. KVM must be prevent host
userspace from accessing guest memory irrespective of hardware behavior.

Attempt #1 to support CoCo VMs was to add a VMA flag to mark memory as
being mappable only by KVM (or a similarly enlightened kernel subsystem).
That approach was abandoned largely due to it needing to play games with
PROT_NONE to prevent userspace from accessing guest memory.

Attempt #2 to was to usurp PG_hwpoison to prevent the host from mapping
guest private memory into userspace, but that approach failed to meet
several requirements for software-based CoCo VMs, e.g. pKVM, as the kernel
wouldn't easily be able to enforce a 1:1 page:guest association, let alone
a 1:1 pfn:gfn mapping.  And using PG_hwpoison does not work for memory
that isn't backed by 'struct page', e.g. if devices gain support for
exposing encrypted memory regions to guests.

Attempt #3 was to extend the memfd() syscall and wrap shmem to provide
dedicated file-based guest memory.  That approach made it as far as v10
before feedback from Hugh Dickins and Christian Brauner (and others) led
to it demise.

Hugh's objection was that piggybacking shmem made no sense for KVM's use
case as KVM didn't actually *want* the features provided by shmem.  I.e.
KVM was using memfd() and shmem to avoid having to manage memory directly,
not because memfd() and shmem were the optimal solution, e.g. things like
read/write/mmap in shmem were dead weight.

Christian pointed out flaws with implementing a partial overlay (wrapping
only _some_ of shmem), e.g. poking at inode_operations or super_operations
would show shmem stuff, but address_space_operations and file_operations
would show KVM's overlay.  Paraphrashing heavily, Christian suggested KVM
stop being lazy and create a proper API.

Link: https://lore.kernel.org/all/20201020061859.18385-1-kirill.shutemov@linux.intel.com
Link: https://lore.kernel.org/all/20210416154106.23721-1-kirill.shutemov@linux.intel.com
Link: https://lore.kernel.org/all/20210824005248.200037-1-seanjc@google.com
Link: https://lore.kernel.org/all/20211111141352.26311-1-chao.p.peng@linux.intel.com
Link: https://lore.kernel.org/all/20221202061347.1070246-1-chao.p.peng@linux.intel.com
Link: https://lore.kernel.org/all/ff5c5b97-acdf-9745-ebe5-c6609dd6322e@google.com
Link: https://lore.kernel.org/all/20230418-anfallen-irdisch-6993a61be10b@brauner
Link: https://lore.kernel.org/all/ZEM5Zq8oo+xnApW9@google.com
Link: https://lore.kernel.org/linux-mm/20230306191944.GA15773@monkey
Link: https://lore.kernel.org/linux-mm/ZII1p8ZHlHaQ3dDl@casper.infradead.org
Cc: Fuad Tabba <tabba@google.com>
Cc: Vishal Annapurve <vannapurve@google.com>
Cc: Ackerley Tng <ackerleytng@google.com>
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Maciej Szmigiero <mail@maciej.szmigiero.name>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Quentin Perret <qperret@google.com>
Cc: Michael Roth <michael.roth@amd.com>
Cc: Wang <wei.w.wang@intel.com>
Cc: Liam Merwick <liam.merwick@oracle.com>
Cc: Isaku Yamahata <isaku.yamahata@gmail.com>
Co-developed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Co-developed-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Co-developed-by: Chao Peng <chao.p.peng@linux.intel.com>
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Co-developed-by: Ackerley Tng <ackerleytng@google.com>
Signed-off-by: Ackerley Tng <ackerleytng@google.com>
Co-developed-by: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Co-developed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Co-developed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20231027182217.3615211-17-seanjc@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-11-14 08:01:03 -05:00
Chao Peng
5a475554db KVM: Introduce per-page memory attributes
In confidential computing usages, whether a page is private or shared is
necessary information for KVM to perform operations like page fault
handling, page zapping etc. There are other potential use cases for
per-page memory attributes, e.g. to make memory read-only (or no-exec,
or exec-only, etc.) without having to modify memslots.

Introduce the KVM_SET_MEMORY_ATTRIBUTES ioctl, advertised by
KVM_CAP_MEMORY_ATTRIBUTES, to allow userspace to set the per-page memory
attributes to a guest memory range.

Use an xarray to store the per-page attributes internally, with a naive,
not fully optimized implementation, i.e. prioritize correctness over
performance for the initial implementation.

Use bit 3 for the PRIVATE attribute so that KVM can use bits 0-2 for RWX
attributes/protections in the future, e.g. to give userspace fine-grained
control over read, write, and execute protections for guest memory.

Provide arch hooks for handling attribute changes before and after common
code sets the new attributes, e.g. x86 will use the "pre" hook to zap all
relevant mappings, and the "post" hook to track whether or not hugepages
can be used to map the range.

To simplify the implementation wrap the entire sequence with
kvm_mmu_invalidate_{begin,end}() even though the operation isn't strictly
guaranteed to be an invalidation.  For the initial use case, x86 *will*
always invalidate memory, and preventing arch code from creating new
mappings while the attributes are in flux makes it much easier to reason
about the correctness of consuming attributes.

It's possible that future usages may not require an invalidation, e.g.
if KVM ends up supporting RWX protections and userspace grants _more_
protections, but again opt for simplicity and punt optimizations to
if/when they are needed.

Suggested-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/all/Y2WB48kD0J4VGynX@google.com
Cc: Fuad Tabba <tabba@google.com>
Cc: Xu Yilun <yilun.xu@intel.com>
Cc: Mickaël Salaün <mic@digikod.net>
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20231027182217.3615211-14-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-11-13 05:31:38 -05:00
Chao Peng
16f95f3b95 KVM: Add KVM_EXIT_MEMORY_FAULT exit to report faults to userspace
Add a new KVM exit type to allow userspace to handle memory faults that
KVM cannot resolve, but that userspace *may* be able to handle (without
terminating the guest).

KVM will initially use KVM_EXIT_MEMORY_FAULT to report implicit
conversions between private and shared memory.  With guest private memory,
there will be two kind of memory conversions:

  - explicit conversion: happens when the guest explicitly calls into KVM
    to map a range (as private or shared)

  - implicit conversion: happens when the guest attempts to access a gfn
    that is configured in the "wrong" state (private vs. shared)

On x86 (first architecture to support guest private memory), explicit
conversions will be reported via KVM_EXIT_HYPERCALL+KVM_HC_MAP_GPA_RANGE,
but reporting KVM_EXIT_HYPERCALL for implicit conversions is undesriable
as there is (obviously) no hypercall, and there is no guarantee that the
guest actually intends to convert between private and shared, i.e. what
KVM thinks is an implicit conversion "request" could actually be the
result of a guest code bug.

KVM_EXIT_MEMORY_FAULT will be used to report memory faults that appear to
be implicit conversions.

Note!  To allow for future possibilities where KVM reports
KVM_EXIT_MEMORY_FAULT and fills run->memory_fault on _any_ unresolved
fault, KVM returns "-EFAULT" (-1 with errno == EFAULT from userspace's
perspective), not '0'!  Due to historical baggage within KVM, exiting to
userspace with '0' from deep callstacks, e.g. in emulation paths, is
infeasible as doing so would require a near-complete overhaul of KVM,
whereas KVM already propagates -errno return codes to userspace even when
the -errno originated in a low level helper.

Report the gpa+size instead of a single gfn even though the initial usage
is expected to always report single pages.  It's entirely possible, likely
even, that KVM will someday support sub-page granularity faults, e.g.
Intel's sub-page protection feature allows for additional protections at
128-byte granularity.

Link: https://lore.kernel.org/all/20230908222905.1321305-5-amoorthy@google.com
Link: https://lore.kernel.org/all/ZQ3AmLO2SYv3DszH@google.com
Cc: Anish Moorthy <amoorthy@google.com>
Cc: David Matlack <dmatlack@google.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Co-developed-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20231027182217.3615211-10-seanjc@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-11-13 05:31:11 -05:00
Sean Christopherson
bb58b90b1a KVM: Introduce KVM_SET_USER_MEMORY_REGION2
Introduce a "version 2" of KVM_SET_USER_MEMORY_REGION so that additional
information can be supplied without setting userspace up to fail.  The
padding in the new kvm_userspace_memory_region2 structure will be used to
pass a file descriptor in addition to the userspace_addr, i.e. allow
userspace to point at a file descriptor and map memory into a guest that
is NOT mapped into host userspace.

Alternatively, KVM could simply add "struct kvm_userspace_memory_region2"
without a new ioctl(), but as Paolo pointed out, adding a new ioctl()
makes detection of bad flags a bit more robust, e.g. if the new fd field
is guarded only by a flag and not a new ioctl(), then a userspace bug
(setting a "bad" flag) would generate out-of-bounds access instead of an
-EINVAL error.

Cc: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Message-Id: <20231027182217.3615211-9-seanjc@google.com>
Acked-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-11-13 05:30:41 -05:00
Paolo Bonzini
45b890f768 KVM/arm64 updates for 6.7
- Generalized infrastructure for 'writable' ID registers, effectively
    allowing userspace to opt-out of certain vCPU features for its guest
 
  - Optimization for vSGI injection, opportunistically compressing MPIDR
    to vCPU mapping into a table
 
  - Improvements to KVM's PMU emulation, allowing userspace to select
    the number of PMCs available to a VM
 
  - Guest support for memory operation instructions (FEAT_MOPS)
 
  - Cleanups to handling feature flags in KVM_ARM_VCPU_INIT, squashing
    bugs and getting rid of useless code
 
  - Changes to the way the SMCCC filter is constructed, avoiding wasted
    memory allocations when not in use
 
  - Load the stage-2 MMU context at vcpu_load() for VHE systems, reducing
    the overhead of errata mitigations
 
  - Miscellaneous kernel and selftest fixes
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Merge tag 'kvmarm-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 updates for 6.7

 - Generalized infrastructure for 'writable' ID registers, effectively
   allowing userspace to opt-out of certain vCPU features for its guest

 - Optimization for vSGI injection, opportunistically compressing MPIDR
   to vCPU mapping into a table

 - Improvements to KVM's PMU emulation, allowing userspace to select
   the number of PMCs available to a VM

 - Guest support for memory operation instructions (FEAT_MOPS)

 - Cleanups to handling feature flags in KVM_ARM_VCPU_INIT, squashing
   bugs and getting rid of useless code

 - Changes to the way the SMCCC filter is constructed, avoiding wasted
   memory allocations when not in use

 - Load the stage-2 MMU context at vcpu_load() for VHE systems, reducing
   the overhead of errata mitigations

 - Miscellaneous kernel and selftest fixes
2023-10-31 16:37:07 -04:00
Paolo Bonzini
fadaf574a7 KVM x86 Documentation updates for 6.7:
- Fix various typos, notably a confusing reference to the non-existent
    "struct kvm_vcpu_event" (the actual structure is kvm_vcpu_events, plural).
 
  - Update x86's kvm_mmu_page documentation to bring it closer to the code
    (this raced with the removal of async zapping and so the documentation is
    already stale; my bad).
 
  - Document the behavior of x86 PMU filters on fixed counters.
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Merge tag 'kvm-x86-docs-6.7' of https://github.com/kvm-x86/linux into HEAD

KVM x86 Documentation updates for 6.7:

 - Fix various typos, notably a confusing reference to the non-existent
   "struct kvm_vcpu_event" (the actual structure is kvm_vcpu_events, plural).

 - Update x86's kvm_mmu_page documentation to bring it closer to the code
   (this raced with the removal of async zapping and so the documentation is
   already stale; my bad).

 - Document the behavior of x86 PMU filters on fixed counters.
2023-10-31 10:12:45 -04:00
Oliver Upton
a87a36436c Merge branch kvm-arm64/writable-id-regs into kvmarm/next
* kvm-arm64/writable-id-regs:
  : Writable ID registers, courtesy of Jing Zhang
  :
  : This series significantly expands the architectural feature set that
  : userspace can manipulate via the ID registers. A new ioctl is defined
  : that makes the mutable fields in the ID registers discoverable to
  : userspace.
  KVM: selftests: Avoid using forced target for generating arm64 headers
  tools headers arm64: Fix references to top srcdir in Makefile
  KVM: arm64: selftests: Test for setting ID register from usersapce
  tools headers arm64: Update sysreg.h with kernel sources
  KVM: selftests: Generate sysreg-defs.h and add to include path
  perf build: Generate arm64's sysreg-defs.h and add to include path
  tools: arm64: Add a Makefile for generating sysreg-defs.h
  KVM: arm64: Document vCPU feature selection UAPIs
  KVM: arm64: Allow userspace to change ID_AA64ZFR0_EL1
  KVM: arm64: Allow userspace to change ID_AA64PFR0_EL1
  KVM: arm64: Allow userspace to change ID_AA64MMFR{0-2}_EL1
  KVM: arm64: Allow userspace to change ID_AA64ISAR{0-2}_EL1
  KVM: arm64: Bump up the default KVM sanitised debug version to v8p8
  KVM: arm64: Reject attempts to set invalid debug arch version
  KVM: arm64: Advertise selected DebugVer in DBGDIDR.Version
  KVM: arm64: Use guest ID register values for the sake of emulation
  KVM: arm64: Document KVM_ARM_GET_REG_WRITABLE_MASKS
  KVM: arm64: Allow userspace to get the writable masks for feature ID registers

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
2023-10-30 20:21:09 +00:00
Oliver Upton
dafa493dd0 KVM: arm64: Document vCPU feature selection UAPIs
KVM/arm64 has a couple schemes for handling vCPU feature selection now,
which is a lot to put on userspace. Add some documentation about how
these interact and provide some recommendations for how to use the
writable ID register scheme.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231003230408.3405722-11-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
2023-10-04 17:11:51 +00:00
Jing Zhang
6656cda0f3 KVM: arm64: Document KVM_ARM_GET_REG_WRITABLE_MASKS
Add some basic documentation on how to get feature ID register writable
masks from userspace.

Signed-off-by: Jing Zhang <jingzhangos@google.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231003230408.3405722-3-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
2023-10-04 17:10:15 +00:00
Tianrui Zhao
6f0257a032 LoongArch: KVM: Supplement kvm document about LoongArch-specific part
Supplement kvm document about LoongArch-specific part, such as add
api introduction for GET/SET_ONE_REG, GET/SET_FPU, GET/SET_MP_STATE,
etc.

Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Tianrui Zhao <zhaotianrui@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2023-10-02 10:01:29 +08:00