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Mon, 14 Jul 2025 04:05:18 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHLxe6Pv/JAq/DYpkZ9Ch0HlrtQArZruWL1hai16doCi9lEvmYo5lsLITD8YKLLtQj9syEWDg== X-Received: by 2002:a05:6000:43d8:b0:3a5:276b:1ec0 with SMTP id ffacd0b85a97d-3b5f18eb539mr7587509f8f.45.1752491117369; Mon, 14 Jul 2025 04:05:17 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Cc: Roy Hopkins , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , Stefano Garzarella , Pankaj Gupta , "Michael S. Tsirkin" , Gerd Hoffman , Ani Sinha Subject: [PULL 26/77] docs/system: Add documentation on support for IGVM Date: Mon, 14 Jul 2025 13:03:15 +0200 Message-ID: <20250714110406.117772-27-pbonzini@redhat.com> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20250714110406.117772-1-pbonzini@redhat.com> References: <20250714110406.117772-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1752492449092116600 From: Roy Hopkins IGVM support has been implemented for Confidential Guests that support AMD SEV and AMD SEV-ES. Add some documentation that gives some background on the IGVM format and how to use it to configure a confidential guest. Signed-off-by: Roy Hopkins Reviewed-by: Daniel P. Berrang=C3=A9 Reviewed-by: Stefano Garzarella Reviewed-by: Pankaj Gupta Acked-by: Michael S. Tsirkin Acked-by: Gerd Hoffman Reviewed-by: Ani Sinha Link: https://lore.kernel.org/r/b4dc920a30717e19cd79bbbe2cc769f3b9ff3d37.17= 51554099.git.roy.hopkins@randomman.co.uk Signed-off-by: Paolo Bonzini --- docs/system/i386/amd-memory-encryption.rst | 2 + docs/system/igvm.rst | 173 +++++++++++++++++++++ docs/system/index.rst | 1 + 3 files changed, 176 insertions(+) create mode 100644 docs/system/igvm.rst diff --git a/docs/system/i386/amd-memory-encryption.rst b/docs/system/i386/= amd-memory-encryption.rst index 748f5094baf..6c23f3535f4 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) =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =20 diff --git a/docs/system/igvm.rst b/docs/system/igvm.rst new file mode 100644 index 00000000000..79508d95880 --- /dev/null +++ b/docs/system/igvm.rst @@ -0,0 +1,173 @@ +Independent Guest Virtual Machine (IGVM) support +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +IGVM files are designed to encapsulate all the information required to lau= nch a +virtual machine on any given virtualization stack in a deterministic way. = This +allows the cryptographic measurement of initial guest state for Confidenti= al +Guests to be calculated when the IGVM file is built, allowing a relying pa= rty 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. T= his +object is used to define the filename of the IGVM file to process. A refer= ence +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 specifica= tion +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 syst= ems +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 directi= ves. +Not every directive is supported by every Confidential Guest type. For exa= mple, +AMD SEV does not support encrypted save state regions, therefore setting t= he +initial CPU state using IGVM for SEV is not possible. When an IGVM file co= ntains +directives that are not supported for the active platform, an error is gen= erated +and the guest launch is aborted. + +The table below describes the list of directives that are supported for SE= V, +SEV-ES, SEV-SNP and non-confidential platforms. + +.. list-table:: SEV, SEV-ES, SEV-SNP & non-confidential Supported Directiv= es + :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 paramet= er + 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 CP= Us 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 SE= V-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 a= nd +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 gu= est. +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, S= S, +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, suc= h 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 p= flash +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 f= ile +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 gen= erate +IGVM files for non-confidential X86 platforms as well as for SEV, SEV-ES a= nd +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 \ + \ + -machine ...,confidential-guest-support=3Dsev0,igvm-cfg=3Digvm0 \ + -object sev-guest,id=3Dsev0,cbitpos=3D47,reduced-phys-bits=3D1 \ + -object igvm-cfg,id=3Digvm0,file=3D/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/pro= grammer-references/24593.pdf + +[2] ``buildigvm`` - A tool to build example IGVM files containing OVMF fir= mware + 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 718e9d3c56b..427b0204831 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 --=20 2.50.0