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Changeset58ad30cf91("docs: fix reference to core-api/namespaces.rst") enabled a new feature at Sphinx: it will now generate index for each document title, plus to each chapter inside it. There's a drawback, though: one document cannot have two sections with the same name anymore. A followup patch will change the logic of autosectionlabel to avoid most creating references for every single section title, but still we need to be able to reference the chapters inside a document. There are a few places where there are two chapters with the same name. This patch renames one of the chapters, in order to avoid symbol conflict within the same document. PS.: as I don't speach Chinese, I had some help from a friend (Wen Liu) at the Chinese translation for "publishing patches" for this document: Documentation/translations/zh_CN/process/5.Posting.rst Fixes:58ad30cf91("docs: fix reference to core-api/namespaces.rst") Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Link: https://lore.kernel.org/r/2bffb91e4a63d41bf5fae1c23e1e8b3bba0b8806.1584716446.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
1115 lines
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ReStructuredText
1115 lines
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ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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.. _ultravisor:
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============================
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Protected Execution Facility
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============================
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.. contents::
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:depth: 3
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Introduction
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############
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Protected Execution Facility (PEF) is an architectural change for
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POWER 9 that enables Secure Virtual Machines (SVMs). DD2.3 chips
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(PVR=0x004e1203) or greater will be PEF-capable. A new ISA release
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will include the PEF RFC02487 changes.
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When enabled, PEF adds a new higher privileged mode, called Ultravisor
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mode, to POWER architecture. Along with the new mode there is new
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firmware called the Protected Execution Ultravisor (or Ultravisor
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for short). Ultravisor mode is the highest privileged mode in POWER
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architecture.
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+------------------+
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| Privilege States |
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+==================+
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| Problem |
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+------------------+
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| Supervisor |
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+------------------+
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| Hypervisor |
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+------------------+
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| Ultravisor |
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+------------------+
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PEF protects SVMs from the hypervisor, privileged users, and other
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VMs in the system. SVMs are protected while at rest and can only be
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executed by an authorized machine. All virtual machines utilize
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hypervisor services. The Ultravisor filters calls between the SVMs
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and the hypervisor to assure that information does not accidentally
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leak. All hypercalls except H_RANDOM are reflected to the hypervisor.
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H_RANDOM is not reflected to prevent the hypervisor from influencing
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random values in the SVM.
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To support this there is a refactoring of the ownership of resources
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in the CPU. Some of the resources which were previously hypervisor
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privileged are now ultravisor privileged.
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Hardware
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========
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The hardware changes include the following:
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* There is a new bit in the MSR that determines whether the current
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process is running in secure mode, MSR(S) bit 41. MSR(S)=1, process
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is in secure mode, MSR(s)=0 process is in normal mode.
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* The MSR(S) bit can only be set by the Ultravisor.
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* HRFID cannot be used to set the MSR(S) bit. If the hypervisor needs
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to return to a SVM it must use an ultracall. It can determine if
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the VM it is returning to is secure.
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* There is a new Ultravisor privileged register, SMFCTRL, which has an
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enable/disable bit SMFCTRL(E).
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* The privilege of a process is now determined by three MSR bits,
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MSR(S, HV, PR). In each of the tables below the modes are listed
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from least privilege to highest privilege. The higher privilege
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modes can access all the resources of the lower privilege modes.
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**Secure Mode MSR Settings**
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+---+---+---+---------------+
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| S | HV| PR|Privilege |
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+===+===+===+===============+
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| 1 | 0 | 1 | Problem |
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+---+---+---+---------------+
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| 1 | 0 | 0 | Privileged(OS)|
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+---+---+---+---------------+
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| 1 | 1 | 0 | Ultravisor |
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+---+---+---+---------------+
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| 1 | 1 | 1 | Reserved |
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+---+---+---+---------------+
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**Normal Mode MSR Settings**
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+---+---+---+---------------+
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| S | HV| PR|Privilege |
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+===+===+===+===============+
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| 0 | 0 | 1 | Problem |
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+---+---+---+---------------+
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| 0 | 0 | 0 | Privileged(OS)|
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+---+---+---+---------------+
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| 0 | 1 | 0 | Hypervisor |
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+---+---+---+---------------+
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| 0 | 1 | 1 | Problem (Host)|
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+---+---+---+---------------+
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* Memory is partitioned into secure and normal memory. Only processes
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that are running in secure mode can access secure memory.
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* The hardware does not allow anything that is not running secure to
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access secure memory. This means that the Hypervisor cannot access
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the memory of the SVM without using an ultracall (asking the
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Ultravisor). The Ultravisor will only allow the hypervisor to see
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the SVM memory encrypted.
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* I/O systems are not allowed to directly address secure memory. This
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limits the SVMs to virtual I/O only.
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* The architecture allows the SVM to share pages of memory with the
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hypervisor that are not protected with encryption. However, this
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sharing must be initiated by the SVM.
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* When a process is running in secure mode all hypercalls
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(syscall lev=1) go to the Ultravisor.
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* When a process is in secure mode all interrupts go to the
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Ultravisor.
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* The following resources have become Ultravisor privileged and
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require an Ultravisor interface to manipulate:
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* Processor configurations registers (SCOMs).
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* Stop state information.
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* The debug registers CIABR, DAWR, and DAWRX when SMFCTRL(D) is set.
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If SMFCTRL(D) is not set they do not work in secure mode. When set,
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reading and writing requires an Ultravisor call, otherwise that
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will cause a Hypervisor Emulation Assistance interrupt.
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* PTCR and partition table entries (partition table is in secure
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memory). An attempt to write to PTCR will cause a Hypervisor
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Emulation Assitance interrupt.
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* LDBAR (LD Base Address Register) and IMC (In-Memory Collection)
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non-architected registers. An attempt to write to them will cause a
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Hypervisor Emulation Assistance interrupt.
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* Paging for an SVM, sharing of memory with Hypervisor for an SVM.
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(Including Virtual Processor Area (VPA) and virtual I/O).
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Software/Microcode
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==================
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The software changes include:
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* SVMs are created from normal VM using (open source) tooling supplied
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by IBM.
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* All SVMs start as normal VMs and utilize an ultracall, UV_ESM
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(Enter Secure Mode), to make the transition.
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* When the UV_ESM ultracall is made the Ultravisor copies the VM into
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secure memory, decrypts the verification information, and checks the
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integrity of the SVM. If the integrity check passes the Ultravisor
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passes control in secure mode.
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* The verification information includes the pass phrase for the
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encrypted disk associated with the SVM. This pass phrase is given
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to the SVM when requested.
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* The Ultravisor is not involved in protecting the encrypted disk of
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the SVM while at rest.
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* For external interrupts the Ultravisor saves the state of the SVM,
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and reflects the interrupt to the hypervisor for processing.
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For hypercalls, the Ultravisor inserts neutral state into all
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registers not needed for the hypercall then reflects the call to
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the hypervisor for processing. The H_RANDOM hypercall is performed
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by the Ultravisor and not reflected.
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* For virtual I/O to work bounce buffering must be done.
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* The Ultravisor uses AES (IAPM) for protection of SVM memory. IAPM
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is a mode of AES that provides integrity and secrecy concurrently.
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* The movement of data between normal and secure pages is coordinated
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with the Ultravisor by a new HMM plug-in in the Hypervisor.
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The Ultravisor offers new services to the hypervisor and SVMs. These
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are accessed through ultracalls.
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Terminology
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===========
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* Hypercalls: special system calls used to request services from
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Hypervisor.
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* Normal memory: Memory that is accessible to Hypervisor.
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* Normal page: Page backed by normal memory and available to
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Hypervisor.
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* Shared page: A page backed by normal memory and available to both
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the Hypervisor/QEMU and the SVM (i.e page has mappings in SVM and
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Hypervisor/QEMU).
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* Secure memory: Memory that is accessible only to Ultravisor and
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SVMs.
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* Secure page: Page backed by secure memory and only available to
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Ultravisor and SVM.
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* SVM: Secure Virtual Machine.
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* Ultracalls: special system calls used to request services from
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Ultravisor.
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Ultravisor calls API
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####################
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This section describes Ultravisor calls (ultracalls) needed to
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support Secure Virtual Machines (SVM)s and Paravirtualized KVM. The
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ultracalls allow the SVMs and Hypervisor to request services from the
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Ultravisor such as accessing a register or memory region that can only
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be accessed when running in Ultravisor-privileged mode.
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The specific service needed from an ultracall is specified in register
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R3 (the first parameter to the ultracall). Other parameters to the
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ultracall, if any, are specified in registers R4 through R12.
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Return value of all ultracalls is in register R3. Other output values
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from the ultracall, if any, are returned in registers R4 through R12.
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The only exception to this register usage is the ``UV_RETURN``
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ultracall described below.
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Each ultracall returns specific error codes, applicable in the context
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of the ultracall. However, like with the PowerPC Architecture Platform
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Reference (PAPR), if no specific error code is defined for a
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particular situation, then the ultracall will fallback to an erroneous
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parameter-position based code. i.e U_PARAMETER, U_P2, U_P3 etc
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depending on the ultracall parameter that may have caused the error.
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Some ultracalls involve transferring a page of data between Ultravisor
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and Hypervisor. Secure pages that are transferred from secure memory
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to normal memory may be encrypted using dynamically generated keys.
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When the secure pages are transferred back to secure memory, they may
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be decrypted using the same dynamically generated keys. Generation and
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management of these keys will be covered in a separate document.
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For now this only covers ultracalls currently implemented and being
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used by Hypervisor and SVMs but others can be added here when it
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makes sense.
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The full specification for all hypercalls/ultracalls will eventually
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be made available in the public/OpenPower version of the PAPR
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specification.
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.. note::
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If PEF is not enabled, the ultracalls will be redirected to the
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Hypervisor which must handle/fail the calls.
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Ultracalls used by Hypervisor
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=============================
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This section describes the virtual memory management ultracalls used
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by the Hypervisor to manage SVMs.
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UV_PAGE_OUT
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-----------
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Encrypt and move the contents of a page from secure memory to normal
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memory.
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Syntax
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~~~~~~
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.. code-block:: c
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uint64_t ultracall(const uint64_t UV_PAGE_OUT,
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uint16_t lpid, /* LPAR ID */
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uint64_t dest_ra, /* real address of destination page */
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uint64_t src_gpa, /* source guest-physical-address */
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uint8_t flags, /* flags */
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uint64_t order) /* page size order */
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Return values
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~~~~~~~~~~~~~
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One of the following values:
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* U_SUCCESS on success.
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* U_PARAMETER if ``lpid`` is invalid.
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* U_P2 if ``dest_ra`` is invalid.
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* U_P3 if the ``src_gpa`` address is invalid.
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* U_P4 if any bit in the ``flags`` is unrecognized
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* U_P5 if the ``order`` parameter is unsupported.
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* U_FUNCTION if functionality is not supported.
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* U_BUSY if page cannot be currently paged-out.
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Description
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~~~~~~~~~~~
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Encrypt the contents of a secure-page and make it available to
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Hypervisor in a normal page.
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By default, the source page is unmapped from the SVM's partition-
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scoped page table. But the Hypervisor can provide a hint to the
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Ultravisor to retain the page mapping by setting the ``UV_SNAPSHOT``
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flag in ``flags`` parameter.
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If the source page is already a shared page the call returns
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U_SUCCESS, without doing anything.
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Use cases
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~~~~~~~~~
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#. QEMU attempts to access an address belonging to the SVM but the
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page frame for that address is not mapped into QEMU's address
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space. In this case, the Hypervisor will allocate a page frame,
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map it into QEMU's address space and issue the ``UV_PAGE_OUT``
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call to retrieve the encrypted contents of the page.
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#. When Ultravisor runs low on secure memory and it needs to page-out
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an LRU page. In this case, Ultravisor will issue the
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``H_SVM_PAGE_OUT`` hypercall to the Hypervisor. The Hypervisor will
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then allocate a normal page and issue the ``UV_PAGE_OUT`` ultracall
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and the Ultravisor will encrypt and move the contents of the secure
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page into the normal page.
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#. When Hypervisor accesses SVM data, the Hypervisor requests the
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Ultravisor to transfer the corresponding page into a insecure page,
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which the Hypervisor can access. The data in the normal page will
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be encrypted though.
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UV_PAGE_IN
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----------
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Move the contents of a page from normal memory to secure memory.
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Syntax
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~~~~~~
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.. code-block:: c
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uint64_t ultracall(const uint64_t UV_PAGE_IN,
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uint16_t lpid, /* the LPAR ID */
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uint64_t src_ra, /* source real address of page */
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uint64_t dest_gpa, /* destination guest physical address */
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uint64_t flags, /* flags */
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uint64_t order) /* page size order */
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Return values
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~~~~~~~~~~~~~
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One of the following values:
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* U_SUCCESS on success.
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* U_BUSY if page cannot be currently paged-in.
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* U_FUNCTION if functionality is not supported
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* U_PARAMETER if ``lpid`` is invalid.
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* U_P2 if ``src_ra`` is invalid.
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* U_P3 if the ``dest_gpa`` address is invalid.
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* U_P4 if any bit in the ``flags`` is unrecognized
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* U_P5 if the ``order`` parameter is unsupported.
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Description
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~~~~~~~~~~~
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Move the contents of the page identified by ``src_ra`` from normal
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memory to secure memory and map it to the guest physical address
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``dest_gpa``.
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If `dest_gpa` refers to a shared address, map the page into the
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partition-scoped page-table of the SVM. If `dest_gpa` is not shared,
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copy the contents of the page into the corresponding secure page.
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Depending on the context, decrypt the page before being copied.
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The caller provides the attributes of the page through the ``flags``
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parameter. Valid values for ``flags`` are:
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* CACHE_INHIBITED
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* CACHE_ENABLED
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* WRITE_PROTECTION
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The Hypervisor must pin the page in memory before making
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``UV_PAGE_IN`` ultracall.
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Use cases
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~~~~~~~~~
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#. When a normal VM switches to secure mode, all its pages residing
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in normal memory, are moved into secure memory.
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#. When an SVM requests to share a page with Hypervisor the Hypervisor
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allocates a page and informs the Ultravisor.
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#. When an SVM accesses a secure page that has been paged-out,
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Ultravisor invokes the Hypervisor to locate the page. After
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locating the page, the Hypervisor uses UV_PAGE_IN to make the
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page available to Ultravisor.
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UV_PAGE_INVAL
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-------------
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Invalidate the Ultravisor mapping of a page.
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Syntax
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~~~~~~
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.. code-block:: c
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uint64_t ultracall(const uint64_t UV_PAGE_INVAL,
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uint16_t lpid, /* the LPAR ID */
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uint64_t guest_pa, /* destination guest-physical-address */
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uint64_t order) /* page size order */
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Return values
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~~~~~~~~~~~~~
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One of the following values:
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* U_SUCCESS on success.
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* U_PARAMETER if ``lpid`` is invalid.
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* U_P2 if ``guest_pa`` is invalid (or corresponds to a secure
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page mapping).
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* U_P3 if the ``order`` is invalid.
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* U_FUNCTION if functionality is not supported.
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* U_BUSY if page cannot be currently invalidated.
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Description
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~~~~~~~~~~~
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This ultracall informs Ultravisor that the page mapping in Hypervisor
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corresponding to the given guest physical address has been invalidated
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and that the Ultravisor should not access the page. If the specified
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``guest_pa`` corresponds to a secure page, Ultravisor will ignore the
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attempt to invalidate the page and return U_P2.
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Use cases
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~~~~~~~~~
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#. When a shared page is unmapped from the QEMU's page table, possibly
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because it is paged-out to disk, Ultravisor needs to know that the
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page should not be accessed from its side too.
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UV_WRITE_PATE
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-------------
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Validate and write the partition table entry (PATE) for a given
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partition.
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Syntax
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~~~~~~
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.. code-block:: c
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uint64_t ultracall(const uint64_t UV_WRITE_PATE,
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uint32_t lpid, /* the LPAR ID */
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uint64_t dw0 /* the first double word to write */
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uint64_t dw1) /* the second double word to write */
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Return values
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~~~~~~~~~~~~~
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One of the following values:
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* U_SUCCESS on success.
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* U_BUSY if PATE cannot be currently written to.
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* U_FUNCTION if functionality is not supported.
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* U_PARAMETER if ``lpid`` is invalid.
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* U_P2 if ``dw0`` is invalid.
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* U_P3 if the ``dw1`` address is invalid.
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* U_PERMISSION if the Hypervisor is attempting to change the PATE
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of a secure virtual machine or if called from a
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context other than Hypervisor.
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Description
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~~~~~~~~~~~
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Validate and write a LPID and its partition-table-entry for the given
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LPID. If the LPID is already allocated and initialized, this call
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results in changing the partition table entry.
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Use cases
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~~~~~~~~~
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#. The Partition table resides in Secure memory and its entries,
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called PATE (Partition Table Entries), point to the partition-
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scoped page tables for the Hypervisor as well as each of the
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virtual machines (both secure and normal). The Hypervisor
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operates in partition 0 and its partition-scoped page tables
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reside in normal memory.
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#. This ultracall allows the Hypervisor to register the partition-
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scoped and process-scoped page table entries for the Hypervisor
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and other partitions (virtual machines) with the Ultravisor.
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#. If the value of the PATE for an existing partition (VM) changes,
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the TLB cache for the partition is flushed.
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#. The Hypervisor is responsible for allocating LPID. The LPID and
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its PATE entry are registered together. The Hypervisor manages
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the PATE entries for a normal VM and can change the PATE entry
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anytime. Ultravisor manages the PATE entries for an SVM and
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Hypervisor is not allowed to modify them.
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UV_RETURN
|
|
---------
|
|
|
|
Return control from the Hypervisor back to the Ultravisor after
|
|
processing an hypercall or interrupt that was forwarded (aka
|
|
*reflected*) to the Hypervisor.
|
|
|
|
Syntax
|
|
~~~~~~
|
|
|
|
.. code-block:: c
|
|
|
|
uint64_t ultracall(const uint64_t UV_RETURN)
|
|
|
|
Return values
|
|
~~~~~~~~~~~~~
|
|
|
|
This call never returns to Hypervisor on success. It returns
|
|
U_INVALID if ultracall is not made from a Hypervisor context.
|
|
|
|
Description
|
|
~~~~~~~~~~~
|
|
|
|
When an SVM makes an hypercall or incurs some other exception, the
|
|
Ultravisor usually forwards (aka *reflects*) the exceptions to the
|
|
Hypervisor. After processing the exception, Hypervisor uses the
|
|
``UV_RETURN`` ultracall to return control back to the SVM.
|
|
|
|
The expected register state on entry to this ultracall is:
|
|
|
|
* Non-volatile registers are restored to their original values.
|
|
* If returning from an hypercall, register R0 contains the return
|
|
value (**unlike other ultracalls**) and, registers R4 through R12
|
|
contain any output values of the hypercall.
|
|
* R3 contains the ultracall number, i.e UV_RETURN.
|
|
* If returning with a synthesized interrupt, R2 contains the
|
|
synthesized interrupt number.
|
|
|
|
Use cases
|
|
~~~~~~~~~
|
|
|
|
#. Ultravisor relies on the Hypervisor to provide several services to
|
|
the SVM such as processing hypercall and other exceptions. After
|
|
processing the exception, Hypervisor uses UV_RETURN to return
|
|
control back to the Ultravisor.
|
|
|
|
#. Hypervisor has to use this ultracall to return control to the SVM.
|
|
|
|
|
|
UV_REGISTER_MEM_SLOT
|
|
--------------------
|
|
|
|
Register an SVM address-range with specified properties.
|
|
|
|
Syntax
|
|
~~~~~~
|
|
|
|
.. code-block:: c
|
|
|
|
uint64_t ultracall(const uint64_t UV_REGISTER_MEM_SLOT,
|
|
uint64_t lpid, /* LPAR ID of the SVM */
|
|
uint64_t start_gpa, /* start guest physical address */
|
|
uint64_t size, /* size of address range in bytes */
|
|
uint64_t flags /* reserved for future expansion */
|
|
uint16_t slotid) /* slot identifier */
|
|
|
|
Return values
|
|
~~~~~~~~~~~~~
|
|
|
|
One of the following values:
|
|
|
|
* U_SUCCESS on success.
|
|
* U_PARAMETER if ``lpid`` is invalid.
|
|
* U_P2 if ``start_gpa`` is invalid.
|
|
* U_P3 if ``size`` is invalid.
|
|
* U_P4 if any bit in the ``flags`` is unrecognized.
|
|
* U_P5 if the ``slotid`` parameter is unsupported.
|
|
* U_PERMISSION if called from context other than Hypervisor.
|
|
* U_FUNCTION if functionality is not supported.
|
|
|
|
|
|
Description
|
|
~~~~~~~~~~~
|
|
|
|
Register a memory range for an SVM. The memory range starts at the
|
|
guest physical address ``start_gpa`` and is ``size`` bytes long.
|
|
|
|
Use cases
|
|
~~~~~~~~~
|
|
|
|
|
|
#. When a virtual machine goes secure, all the memory slots managed by
|
|
the Hypervisor move into secure memory. The Hypervisor iterates
|
|
through each of memory slots, and registers the slot with
|
|
Ultravisor. Hypervisor may discard some slots such as those used
|
|
for firmware (SLOF).
|
|
|
|
#. When new memory is hot-plugged, a new memory slot gets registered.
|
|
|
|
|
|
UV_UNREGISTER_MEM_SLOT
|
|
----------------------
|
|
|
|
Unregister an SVM address-range that was previously registered using
|
|
UV_REGISTER_MEM_SLOT.
|
|
|
|
Syntax
|
|
~~~~~~
|
|
|
|
.. code-block:: c
|
|
|
|
uint64_t ultracall(const uint64_t UV_UNREGISTER_MEM_SLOT,
|
|
uint64_t lpid, /* LPAR ID of the SVM */
|
|
uint64_t slotid) /* reservation slotid */
|
|
|
|
Return values
|
|
~~~~~~~~~~~~~
|
|
|
|
One of the following values:
|
|
|
|
* U_SUCCESS on success.
|
|
* U_FUNCTION if functionality is not supported.
|
|
* U_PARAMETER if ``lpid`` is invalid.
|
|
* U_P2 if ``slotid`` is invalid.
|
|
* U_PERMISSION if called from context other than Hypervisor.
|
|
|
|
Description
|
|
~~~~~~~~~~~
|
|
|
|
Release the memory slot identified by ``slotid`` and free any
|
|
resources allocated towards the reservation.
|
|
|
|
Use cases
|
|
~~~~~~~~~
|
|
|
|
#. Memory hot-remove.
|
|
|
|
|
|
UV_SVM_TERMINATE
|
|
----------------
|
|
|
|
Terminate an SVM and release its resources.
|
|
|
|
Syntax
|
|
~~~~~~
|
|
|
|
.. code-block:: c
|
|
|
|
uint64_t ultracall(const uint64_t UV_SVM_TERMINATE,
|
|
uint64_t lpid, /* LPAR ID of the SVM */)
|
|
|
|
Return values
|
|
~~~~~~~~~~~~~
|
|
|
|
One of the following values:
|
|
|
|
* U_SUCCESS on success.
|
|
* U_FUNCTION if functionality is not supported.
|
|
* U_PARAMETER if ``lpid`` is invalid.
|
|
* U_INVALID if VM is not secure.
|
|
* U_PERMISSION if not called from a Hypervisor context.
|
|
|
|
Description
|
|
~~~~~~~~~~~
|
|
|
|
Terminate an SVM and release all its resources.
|
|
|
|
Use cases
|
|
~~~~~~~~~
|
|
|
|
#. Called by Hypervisor when terminating an SVM.
|
|
|
|
|
|
Ultracalls used by SVM
|
|
======================
|
|
|
|
UV_SHARE_PAGE
|
|
-------------
|
|
|
|
Share a set of guest physical pages with the Hypervisor.
|
|
|
|
Syntax
|
|
~~~~~~
|
|
|
|
.. code-block:: c
|
|
|
|
uint64_t ultracall(const uint64_t UV_SHARE_PAGE,
|
|
uint64_t gfn, /* guest page frame number */
|
|
uint64_t num) /* number of pages of size PAGE_SIZE */
|
|
|
|
Return values
|
|
~~~~~~~~~~~~~
|
|
|
|
One of the following values:
|
|
|
|
* U_SUCCESS on success.
|
|
* U_FUNCTION if functionality is not supported.
|
|
* U_INVALID if the VM is not secure.
|
|
* U_PARAMETER if ``gfn`` is invalid.
|
|
* U_P2 if ``num`` is invalid.
|
|
|
|
Description
|
|
~~~~~~~~~~~
|
|
|
|
Share the ``num`` pages starting at guest physical frame number ``gfn``
|
|
with the Hypervisor. Assume page size is PAGE_SIZE bytes. Zero the
|
|
pages before returning.
|
|
|
|
If the address is already backed by a secure page, unmap the page and
|
|
back it with an insecure page, with the help of the Hypervisor. If it
|
|
is not backed by any page yet, mark the PTE as insecure and back it
|
|
with an insecure page when the address is accessed. If it is already
|
|
backed by an insecure page, zero the page and return.
|
|
|
|
Use cases
|
|
~~~~~~~~~
|
|
|
|
#. The Hypervisor cannot access the SVM pages since they are backed by
|
|
secure pages. Hence an SVM must explicitly request Ultravisor for
|
|
pages it can share with Hypervisor.
|
|
|
|
#. Shared pages are needed to support virtio and Virtual Processor Area
|
|
(VPA) in SVMs.
|
|
|
|
|
|
UV_UNSHARE_PAGE
|
|
---------------
|
|
|
|
Restore a shared SVM page to its initial state.
|
|
|
|
Syntax
|
|
~~~~~~
|
|
|
|
.. code-block:: c
|
|
|
|
uint64_t ultracall(const uint64_t UV_UNSHARE_PAGE,
|
|
uint64_t gfn, /* guest page frame number */
|
|
uint73 num) /* number of pages of size PAGE_SIZE*/
|
|
|
|
Return values
|
|
~~~~~~~~~~~~~
|
|
|
|
One of the following values:
|
|
|
|
* U_SUCCESS on success.
|
|
* U_FUNCTION if functionality is not supported.
|
|
* U_INVALID if VM is not secure.
|
|
* U_PARAMETER if ``gfn`` is invalid.
|
|
* U_P2 if ``num`` is invalid.
|
|
|
|
Description
|
|
~~~~~~~~~~~
|
|
|
|
Stop sharing ``num`` pages starting at ``gfn`` with the Hypervisor.
|
|
Assume that the page size is PAGE_SIZE. Zero the pages before
|
|
returning.
|
|
|
|
If the address is already backed by an insecure page, unmap the page
|
|
and back it with a secure page. Inform the Hypervisor to release
|
|
reference to its shared page. If the address is not backed by a page
|
|
yet, mark the PTE as secure and back it with a secure page when that
|
|
address is accessed. If it is already backed by an secure page zero
|
|
the page and return.
|
|
|
|
Use cases
|
|
~~~~~~~~~
|
|
|
|
#. The SVM may decide to unshare a page from the Hypervisor.
|
|
|
|
|
|
UV_UNSHARE_ALL_PAGES
|
|
--------------------
|
|
|
|
Unshare all pages the SVM has shared with Hypervisor.
|
|
|
|
Syntax
|
|
~~~~~~
|
|
|
|
.. code-block:: c
|
|
|
|
uint64_t ultracall(const uint64_t UV_UNSHARE_ALL_PAGES)
|
|
|
|
Return values
|
|
~~~~~~~~~~~~~
|
|
|
|
One of the following values:
|
|
|
|
* U_SUCCESS on success.
|
|
* U_FUNCTION if functionality is not supported.
|
|
* U_INVAL if VM is not secure.
|
|
|
|
Description
|
|
~~~~~~~~~~~
|
|
|
|
Unshare all shared pages from the Hypervisor. All unshared pages are
|
|
zeroed on return. Only pages explicitly shared by the SVM with the
|
|
Hypervisor (using UV_SHARE_PAGE ultracall) are unshared. Ultravisor
|
|
may internally share some pages with the Hypervisor without explicit
|
|
request from the SVM. These pages will not be unshared by this
|
|
ultracall.
|
|
|
|
Use cases
|
|
~~~~~~~~~
|
|
|
|
#. This call is needed when ``kexec`` is used to boot a different
|
|
kernel. It may also be needed during SVM reset.
|
|
|
|
UV_ESM
|
|
------
|
|
|
|
Secure the virtual machine (*enter secure mode*).
|
|
|
|
Syntax
|
|
~~~~~~
|
|
|
|
.. code-block:: c
|
|
|
|
uint64_t ultracall(const uint64_t UV_ESM,
|
|
uint64_t esm_blob_addr, /* location of the ESM blob */
|
|
unint64_t fdt) /* Flattened device tree */
|
|
|
|
Return values
|
|
~~~~~~~~~~~~~
|
|
|
|
One of the following values:
|
|
|
|
* U_SUCCESS on success (including if VM is already secure).
|
|
* U_FUNCTION if functionality is not supported.
|
|
* U_INVALID if VM is not secure.
|
|
* U_PARAMETER if ``esm_blob_addr`` is invalid.
|
|
* U_P2 if ``fdt`` is invalid.
|
|
* U_PERMISSION if any integrity checks fail.
|
|
* U_RETRY insufficient memory to create SVM.
|
|
* U_NO_KEY symmetric key unavailable.
|
|
|
|
Description
|
|
~~~~~~~~~~~
|
|
|
|
Secure the virtual machine. On successful completion, return
|
|
control to the virtual machine at the address specified in the
|
|
ESM blob.
|
|
|
|
Use cases
|
|
~~~~~~~~~
|
|
|
|
#. A normal virtual machine can choose to switch to a secure mode.
|
|
|
|
Hypervisor Calls API
|
|
####################
|
|
|
|
This document describes the Hypervisor calls (hypercalls) that are
|
|
needed to support the Ultravisor. Hypercalls are services provided by
|
|
the Hypervisor to virtual machines and Ultravisor.
|
|
|
|
Register usage for these hypercalls is identical to that of the other
|
|
hypercalls defined in the Power Architecture Platform Reference (PAPR)
|
|
document. i.e on input, register R3 identifies the specific service
|
|
that is being requested and registers R4 through R11 contain
|
|
additional parameters to the hypercall, if any. On output, register
|
|
R3 contains the return value and registers R4 through R9 contain any
|
|
other output values from the hypercall.
|
|
|
|
This document only covers hypercalls currently implemented/planned
|
|
for Ultravisor usage but others can be added here when it makes sense.
|
|
|
|
The full specification for all hypercalls/ultracalls will eventually
|
|
be made available in the public/OpenPower version of the PAPR
|
|
specification.
|
|
|
|
Hypervisor calls to support Ultravisor
|
|
======================================
|
|
|
|
Following are the set of hypercalls needed to support Ultravisor.
|
|
|
|
H_SVM_INIT_START
|
|
----------------
|
|
|
|
Begin the process of converting a normal virtual machine into an SVM.
|
|
|
|
Syntax
|
|
~~~~~~
|
|
|
|
.. code-block:: c
|
|
|
|
uint64_t hypercall(const uint64_t H_SVM_INIT_START)
|
|
|
|
Return values
|
|
~~~~~~~~~~~~~
|
|
|
|
One of the following values:
|
|
|
|
* H_SUCCESS on success.
|
|
|
|
Description
|
|
~~~~~~~~~~~
|
|
|
|
Initiate the process of securing a virtual machine. This involves
|
|
coordinating with the Ultravisor, using ultracalls, to allocate
|
|
resources in the Ultravisor for the new SVM, transferring the VM's
|
|
pages from normal to secure memory etc. When the process is
|
|
completed, Ultravisor issues the H_SVM_INIT_DONE hypercall.
|
|
|
|
Use cases
|
|
~~~~~~~~~
|
|
|
|
#. Ultravisor uses this hypercall to inform Hypervisor that a VM
|
|
has initiated the process of switching to secure mode.
|
|
|
|
|
|
H_SVM_INIT_DONE
|
|
---------------
|
|
|
|
Complete the process of securing an SVM.
|
|
|
|
Syntax
|
|
~~~~~~
|
|
|
|
.. code-block:: c
|
|
|
|
uint64_t hypercall(const uint64_t H_SVM_INIT_DONE)
|
|
|
|
Return values
|
|
~~~~~~~~~~~~~
|
|
|
|
One of the following values:
|
|
|
|
* H_SUCCESS on success.
|
|
* H_UNSUPPORTED if called from the wrong context (e.g.
|
|
from an SVM or before an H_SVM_INIT_START
|
|
hypercall).
|
|
|
|
Description
|
|
~~~~~~~~~~~
|
|
|
|
Complete the process of securing a virtual machine. This call must
|
|
be made after a prior call to ``H_SVM_INIT_START`` hypercall.
|
|
|
|
Use cases
|
|
~~~~~~~~~
|
|
|
|
On successfully securing a virtual machine, the Ultravisor informs
|
|
Hypervisor about it. Hypervisor can use this call to finish setting
|
|
up its internal state for this virtual machine.
|
|
|
|
|
|
H_SVM_INIT_ABORT
|
|
----------------
|
|
|
|
Abort the process of securing an SVM.
|
|
|
|
Syntax
|
|
~~~~~~
|
|
|
|
.. code-block:: c
|
|
|
|
uint64_t hypercall(const uint64_t H_SVM_INIT_ABORT)
|
|
|
|
Return values
|
|
~~~~~~~~~~~~~
|
|
|
|
One of the following values:
|
|
|
|
* H_PARAMETER on successfully cleaning up the state,
|
|
Hypervisor will return this value to the
|
|
**guest**, to indicate that the underlying
|
|
UV_ESM ultracall failed.
|
|
|
|
* H_STATE if called after a VM has gone secure (i.e
|
|
H_SVM_INIT_DONE hypercall was successful).
|
|
|
|
* H_UNSUPPORTED if called from a wrong context (e.g. from a
|
|
normal VM).
|
|
|
|
Description
|
|
~~~~~~~~~~~
|
|
|
|
Abort the process of securing a virtual machine. This call must
|
|
be made after a prior call to ``H_SVM_INIT_START`` hypercall and
|
|
before a call to ``H_SVM_INIT_DONE``.
|
|
|
|
On entry into this hypercall the non-volatile GPRs and FPRs are
|
|
expected to contain the values they had at the time the VM issued
|
|
the UV_ESM ultracall. Further ``SRR0`` is expected to contain the
|
|
address of the instruction after the ``UV_ESM`` ultracall and ``SRR1``
|
|
the MSR value with which to return to the VM.
|
|
|
|
This hypercall will cleanup any partial state that was established for
|
|
the VM since the prior ``H_SVM_INIT_START`` hypercall, including paging
|
|
out pages that were paged-into secure memory, and issue the
|
|
``UV_SVM_TERMINATE`` ultracall to terminate the VM.
|
|
|
|
After the partial state is cleaned up, control returns to the VM
|
|
(**not Ultravisor**), at the address specified in ``SRR0`` with the
|
|
MSR values set to the value in ``SRR1``.
|
|
|
|
Use cases
|
|
~~~~~~~~~
|
|
|
|
If after a successful call to ``H_SVM_INIT_START``, the Ultravisor
|
|
encounters an error while securing a virtual machine, either due
|
|
to lack of resources or because the VM's security information could
|
|
not be validated, Ultravisor informs the Hypervisor about it.
|
|
Hypervisor should use this call to clean up any internal state for
|
|
this virtual machine and return to the VM.
|
|
|
|
H_SVM_PAGE_IN
|
|
-------------
|
|
|
|
Move the contents of a page from normal memory to secure memory.
|
|
|
|
Syntax
|
|
~~~~~~
|
|
|
|
.. code-block:: c
|
|
|
|
uint64_t hypercall(const uint64_t H_SVM_PAGE_IN,
|
|
uint64_t guest_pa, /* guest-physical-address */
|
|
uint64_t flags, /* flags */
|
|
uint64_t order) /* page size order */
|
|
|
|
Return values
|
|
~~~~~~~~~~~~~
|
|
|
|
One of the following values:
|
|
|
|
* H_SUCCESS on success.
|
|
* H_PARAMETER if ``guest_pa`` is invalid.
|
|
* H_P2 if ``flags`` is invalid.
|
|
* H_P3 if ``order`` of page is invalid.
|
|
|
|
Description
|
|
~~~~~~~~~~~
|
|
|
|
Retrieve the content of the page, belonging to the VM at the specified
|
|
guest physical address.
|
|
|
|
Only valid value(s) in ``flags`` are:
|
|
|
|
* H_PAGE_IN_SHARED which indicates that the page is to be shared
|
|
with the Ultravisor.
|
|
|
|
* H_PAGE_IN_NONSHARED indicates that the UV is not anymore
|
|
interested in the page. Applicable if the page is a shared page.
|
|
|
|
The ``order`` parameter must correspond to the configured page size.
|
|
|
|
Use cases
|
|
~~~~~~~~~
|
|
|
|
#. When a normal VM becomes a secure VM (using the UV_ESM ultracall),
|
|
the Ultravisor uses this hypercall to move contents of each page of
|
|
the VM from normal memory to secure memory.
|
|
|
|
#. Ultravisor uses this hypercall to ask Hypervisor to provide a page
|
|
in normal memory that can be shared between the SVM and Hypervisor.
|
|
|
|
#. Ultravisor uses this hypercall to page-in a paged-out page. This
|
|
can happen when the SVM touches a paged-out page.
|
|
|
|
#. If SVM wants to disable sharing of pages with Hypervisor, it can
|
|
inform Ultravisor to do so. Ultravisor will then use this hypercall
|
|
and inform Hypervisor that it has released access to the normal
|
|
page.
|
|
|
|
H_SVM_PAGE_OUT
|
|
---------------
|
|
|
|
Move the contents of the page to normal memory.
|
|
|
|
Syntax
|
|
~~~~~~
|
|
|
|
.. code-block:: c
|
|
|
|
uint64_t hypercall(const uint64_t H_SVM_PAGE_OUT,
|
|
uint64_t guest_pa, /* guest-physical-address */
|
|
uint64_t flags, /* flags (currently none) */
|
|
uint64_t order) /* page size order */
|
|
|
|
Return values
|
|
~~~~~~~~~~~~~
|
|
|
|
One of the following values:
|
|
|
|
* H_SUCCESS on success.
|
|
* H_PARAMETER if ``guest_pa`` is invalid.
|
|
* H_P2 if ``flags`` is invalid.
|
|
* H_P3 if ``order`` is invalid.
|
|
|
|
Description
|
|
~~~~~~~~~~~
|
|
|
|
Move the contents of the page identified by ``guest_pa`` to normal
|
|
memory.
|
|
|
|
Currently ``flags`` is unused and must be set to 0. The ``order``
|
|
parameter must correspond to the configured page size.
|
|
|
|
Use cases
|
|
~~~~~~~~~
|
|
|
|
#. If Ultravisor is running low on secure pages, it can move the
|
|
contents of some secure pages, into normal pages using this
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hypercall. The content will be encrypted.
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References
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##########
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- `Supporting Protected Computing on IBM Power Architecture <https://developer.ibm.com/articles/l-support-protected-computing/>`_
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