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authorStefan Hajnoczi <stefanha@redhat.com>2025-07-14 09:36:57 -0400
committerStefan Hajnoczi <stefanha@redhat.com>2025-07-14 09:36:57 -0400
commitb92b39af4219df4250f121f64d215506909c7404 (patch)
treed112c017e3c77df7341e5fe28072571ad9ecceb8 /docs/system
parent6fae7ce1488e3f5bdcc1747564ea68e7f6f0e931 (diff)
parent5d21ee453ad8e3f95f75e542cb3b35c5bb7cf23a (diff)
downloadfocaccia-qemu-b92b39af4219df4250f121f64d215506909c7404.tar.gz
focaccia-qemu-b92b39af4219df4250f121f64d215506909c7404.zip
Merge tag 'for-upstream' of https://gitlab.com/bonzini/qemu into staging
* rust: miscellaneous fixes
* rust: qemu-api-macros: cleanup and add unit tests for TryInto
* rust: log: implement io::Write, avoid memory allocations
  when logging constant strings
* target/i386: fix usage of properties whenever accelerators
  change the default (e.g. vendor)
* target/i386: add support for TDVMCALL_SETUP_EVENT_NOTIFY_INTERRUPT
* target/i386: add support for booting an SEV VM from an IGVM file
* target/i386: unify cache model descriptions between CPUID 2,
  CPUID 4 and AMD specific CPUID 0x80000006
* target/i386: introduce cache models for recent Intel CPU models
* target/i386: mark some 0x80000000-0x80000008 bits as reserved on Intel
* target/i386: cleanups

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# gpg: Signature made Mon 14 Jul 2025 04:29:31 EDT
# gpg:                using RSA key F13338574B662389866C7682BFFBD25F78C7AE83
# gpg:                issuer "pbonzini@redhat.com"
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>" [full]
# gpg:                 aka "Paolo Bonzini <pbonzini@redhat.com>" [full]
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* tag 'for-upstream' of https://gitlab.com/bonzini/qemu: (77 commits)
  i386/cpu: Honor maximum value for CPUID.8000001DH.EAX[25:14]
  i386/cpu: Fix overflow of cache topology fields in CPUID.04H
  i386/cpu: Fix cpu number overflow in CPUID.01H.EBX[23:16]
  i386/cpu: Fix number of addressable IDs field for CPUID.01H.EBX[23:16]
  i386/cpu: Reorder CPUID leaves in cpu_x86_cpuid()
  tests/vm: bump FreeBSD image to 14.3
  tests/functional: test_x86_cpu_model_versions: remove dead tests
  i386/cpu: Mark CPUID 0x80000008 ECX bits[0:7] & [12:15] as reserved for Intel/Zhaoxin
  i386/cpu: Mark CPUID 0x80000007[EBX] as reserved for Intel
  i386/cpu: Mark EBX/ECX/EDX in CPUID 0x80000000 leaf as reserved for Intel
  i386/cpu: Enable 0x1f leaf for YongFeng by default
  i386/cpu: Enable 0x1f leaf for SapphireRapids by default
  i386/cpu: Enable 0x1f leaf for GraniteRapids by default
  i386/cpu: Enable 0x1f leaf for SierraForest by default
  i386/cpu: Enable 0x1f leaf for SierraForest by default
  i386/cpu: Add a "x-force-cpuid-0x1f" property
  i386/cpu: Introduce cache model for YongFeng
  i386/cpu: Introduce cache model for SapphireRapids
  i386/cpu: Introduce cache model for GraniteRapids
  i386/cpu: Introduce cache model for SierraForest
  ...

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'docs/system')
-rw-r--r--docs/system/i386/amd-memory-encryption.rst2
-rw-r--r--docs/system/igvm.rst173
-rw-r--r--docs/system/index.rst1
3 files changed, 176 insertions, 0 deletions
diff --git a/docs/system/i386/amd-memory-encryption.rst b/docs/system/i386/amd-memory-encryption.rst
index 748f5094ba..6c23f3535f 100644
--- a/docs/system/i386/amd-memory-encryption.rst
+++ b/docs/system/i386/amd-memory-encryption.rst
@@ -1,3 +1,5 @@
+.. _amd-sev:
+
 AMD Secure Encrypted Virtualization (SEV)
 =========================================
 
diff --git a/docs/system/igvm.rst b/docs/system/igvm.rst
new file mode 100644
index 0000000000..79508d9588
--- /dev/null
+++ b/docs/system/igvm.rst
@@ -0,0 +1,173 @@
+Independent Guest Virtual Machine (IGVM) support
+================================================
+
+IGVM files are designed to encapsulate all the information required to launch a
+virtual machine on any given virtualization stack in a deterministic way. This
+allows the cryptographic measurement of initial guest state for Confidential
+Guests to be calculated when the IGVM file is built, allowing a relying party to
+verify the initial state of a guest via a remote attestation.
+
+Although IGVM files are designed with Confidential Computing in mind, they can
+also be used to configure non-confidential guests. Multiple platforms can be
+defined by a single IGVM file, allowing a single IGVM file to configure a
+virtual machine that can run on, for example, TDX, SEV and non-confidential
+hosts.
+
+QEMU supports IGVM files through the user-creatable ``igvm-cfg`` object. This
+object is used to define the filename of the IGVM file to process. A reference
+to the object is added to the ``-machine`` to configure the virtual machine
+to use the IGVM file for configuration.
+
+Confidential platform support is provided through the use of
+the ``ConfidentialGuestSupport`` object. If the virtual machine provides an
+instance of this object then this is used by the IGVM loader to configure the
+isolation properties of the directives within the file.
+
+Further Information on IGVM
+---------------------------
+
+Information about the IGVM format, including links to the format specification
+and documentation for the Rust and C libraries can be found at the project
+repository:
+
+https://github.com/microsoft/igvm
+
+
+Supported Platforms
+-------------------
+
+Currently, IGVM files can be provided for Confidential Guests on host systems
+that support AMD SEV, SEV-ES and SEV-SNP with KVM. IGVM files can also be
+provided for non-confidential guests.
+
+
+Limitations when using IGVM with AMD SEV, SEV-ES and SEV-SNP
+------------------------------------------------------------
+
+IGVM files configure the initial state of the guest using a set of directives.
+Not every directive is supported by every Confidential Guest type. For example,
+AMD SEV does not support encrypted save state regions, therefore setting the
+initial CPU state using IGVM for SEV is not possible. When an IGVM file contains
+directives that are not supported for the active platform, an error is generated
+and the guest launch is aborted.
+
+The table below describes the list of directives that are supported for SEV,
+SEV-ES, SEV-SNP and non-confidential platforms.
+
+.. list-table:: SEV, SEV-ES, SEV-SNP & non-confidential Supported Directives
+   :widths: 35 65
+   :header-rows: 1
+
+   * - IGVM directive
+     - Notes
+   * - IGVM_VHT_PAGE_DATA
+     - ``NORMAL`` zero, measured and unmeasured page types are supported. Other
+       page types result in an error.
+   * - IGVM_VHT_PARAMETER_AREA
+     -
+   * - IGVM_VHT_PARAMETER_INSERT
+     -
+   * - IGVM_VHT_VP_COUNT_PARAMETER
+     - The guest parameter page is populated with the CPU count.
+   * - IGVM_VHT_ENVIRONMENT_INFO_PARAMETER
+     - The ``memory_is_shared`` parameter is set to 1 in the guest parameter
+       page.
+
+.. list-table:: Additional SEV, SEV-ES & SEV_SNP Supported Directives
+   :widths: 25 75
+   :header-rows: 1
+
+   * - IGVM directive
+     - Notes
+   * - IGVM_VHT_MEMORY_MAP
+     - The memory map page is populated using entries from the E820 table.
+   * - IGVM_VHT_REQUIRED_MEMORY
+     - Ensures memory is available in the guest at the specified range.
+
+.. list-table:: Additional SEV-ES & SEV-SNP Supported Directives
+   :widths: 25 75
+   :header-rows: 1
+
+   * - IGVM directive
+     - Notes
+   * - IGVM_VHT_VP_CONTEXT
+     - Setting of the initial CPU state for the boot CPU and additional CPUs is
+       supported with limitations on the fields that can be provided in the
+       VMSA. See below for details on which fields are supported.
+
+Initial CPU state with VMSA
+---------------------------
+
+The initial state of guest CPUs can be defined in the IGVM file for AMD SEV-ES
+and SEV-SNP. The state data is provided as a VMSA structure as defined in Table
+B-4 in the AMD64 Architecture Programmer's Manual, Volume 2 [1].
+
+The IGVM VMSA is translated to CPU state in QEMU which is then synchronized
+by KVM to the guest VMSA during the launch process where it contributes to the
+launch measurement. See :ref:`amd-sev` for details on the launch process and
+guest launch measurement.
+
+It is important that no information is lost or changed when translating the
+VMSA provided by the IGVM file into the VSMA that is used to launch the guest.
+Therefore, QEMU restricts the VMSA fields that can be provided in the IGVM
+VMSA structure to the following registers:
+
+RAX, RCX, RDX, RBX, RBP, RSI, RDI, R8-R15, RSP, RIP, CS, DS, ES, FS, GS, SS,
+CR0, CR3, CR4, XCR0, EFER, PAT, GDT, IDT, LDTR, TR, DR6, DR7, RFLAGS, X87_FCW,
+MXCSR.
+
+When processing the IGVM file, QEMU will check if any fields other than the
+above are non-zero and generate an error if this is the case.
+
+KVM uses a hardcoded GPA of 0xFFFFFFFFF000 for the VMSA. When an IGVM file
+defines initial CPU state, the GPA for each VMSA must match this hardcoded
+value.
+
+Firmware Images with IGVM
+-------------------------
+
+When an IGVM filename is specified for a Confidential Guest Support object it
+overrides the default handling of system firmware: the firmware image, such as
+an OVMF binary should be contained as a payload of the IGVM file and not
+provided as a flash drive or via the ``-bios`` parameter. The default QEMU
+firmware is not automatically populated into the guest memory space.
+
+If an IGVM file is provided along with either the ``-bios`` parameter or pflash
+devices then an error is displayed and the guest startup is aborted.
+
+Running a guest configured using IGVM
+-------------------------------------
+
+To run a guest configured with IGVM you firstly need to generate an IGVM file
+that contains a guest configuration compatible with the platform you are
+targeting.
+
+The ``buildigvm`` tool [2] is an example of a tool that can be used to generate
+IGVM files for non-confidential X86 platforms as well as for SEV, SEV-ES and
+SEV-SNP confidential platforms.
+
+Example using this tool to generate an IGVM file for AMD SEV-SNP::
+
+    buildigvm --firmware /path/to/OVMF.fd --output sev-snp.igvm \
+              --cpucount 4 sev-snp
+
+To run a guest configured with the generated IGVM you need to add an
+``igvm-cfg`` object and refer to it from the ``-machine`` parameter:
+
+Example (for AMD SEV)::
+
+    qemu-system-x86_64 \
+        <other parameters> \
+        -machine ...,confidential-guest-support=sev0,igvm-cfg=igvm0 \
+        -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=1 \
+        -object igvm-cfg,id=igvm0,file=/path/to/sev-snp.igvm
+
+References
+----------
+
+[1] AMD64 Architecture Programmer's Manual, Volume 2: System Programming
+  Rev 3.41
+  https://www.amd.com/content/dam/amd/en/documents/processor-tech-docs/programmer-references/24593.pdf
+
+[2] ``buildigvm`` - A tool to build example IGVM files containing OVMF firmware
+  https://github.com/roy-hopkins/buildigvm
\ No newline at end of file
diff --git a/docs/system/index.rst b/docs/system/index.rst
index 718e9d3c56..427b020483 100644
--- a/docs/system/index.rst
+++ b/docs/system/index.rst
@@ -38,5 +38,6 @@ or Hypervisor.Framework.
    security
    multi-process
    confidential-guest-support
+   igvm
    vm-templating
    sriov