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audk/OvmfPkg/ResetVector/X64/OvmfSevMetadata.asm

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OvmfPkg/ResetVector: introduce SEV metadata descriptor for VMM use BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275 The OvmfPkgX86 build reserves memory regions in MEMFD. The memory regions get accessed in the SEC phase. AMD SEV-SNP require that the guest's private memory be accepted or validated before access. Introduce a Guided metadata structure that describes the reserved memory regions. The VMM can locate the metadata structure by iterating through the reset vector guid and process the areas based on the platform specific requirements. Cc: Michael Roth <michael.roth@amd.com> Cc: James Bottomley <jejb@linux.ibm.com> Cc: Min Xu <min.m.xu@intel.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org> Cc: Erdem Aktas <erdemaktas@google.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
2021-12-09 04:27:32 +01:00
;-----------------------------------------------------------------------------
; @file
; OVMF metadata for the AMD SEV confidential computing guests
;
; Copyright (c) 2021, AMD Inc. All rights reserved.<BR>
;
; SPDX-License-Identifier: BSD-2-Clause-Patent
;-----------------------------------------------------------------------------
BITS 64
%define OVMF_SEV_METADATA_VERSION 1
; The section must be accepted or validated by the VMM before the boot
%define OVMF_SECTION_TYPE_SNP_SEC_MEM 0x1
OvmfPkg: reserve SNP secrets page BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275 During the SNP guest launch sequence, a special secrets page needs to be inserted by the VMM. The PSP will populate the page; it will contain the VM Platform Communication Key (VMPCKs) used by the guest to send and receive secure messages to the PSP. The purpose of the secrets page in the SEV-SNP is different from the one used in SEV guests. In SEV, the secrets page contains the guest owner's private data after the remote attestation. Cc: Michael Roth <michael.roth@amd.com> Cc: James Bottomley <jejb@linux.ibm.com> Cc: Min Xu <min.m.xu@intel.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org> Cc: Erdem Aktas <erdemaktas@google.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Acked-by: Jiewen Yao <Jiewen.yao@intel.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
2021-12-09 04:27:33 +01:00
; AMD SEV-SNP specific sections
%define OVMF_SECTION_TYPE_SNP_SECRETS 0x2
OvmfPkg: reserve CPUID page BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275 Platform features and capabilities are traditionally discovered via the CPUID instruction. Hypervisors typically trap and emulate the CPUID instruction for a variety of reasons. There are some cases where incorrect CPUID information can potentially lead to a security issue. The SEV-SNP firmware provides a feature to filter the CPUID results through the PSP. The filtered CPUID values are saved on a special page for the guest to consume. Reserve a page in MEMFD that will contain the results of filtered CPUID values. Cc: Michael Roth <michael.roth@amd.com> Cc: James Bottomley <jejb@linux.ibm.com> Cc: Min Xu <min.m.xu@intel.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org> Cc: Erdem Aktas <erdemaktas@google.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Acked-by: Jiewen Yao <Jiewen.yao@intel.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
2021-12-09 04:27:34 +01:00
;
; The section contains the hypervisor pre-populated CPUID values.
; In the case of SEV-SNP, the CPUID values are filtered and measured by
; the SEV-SNP firmware.
; The CPUID format is documented in SEV-SNP firmware spec 0.9 section 7.1
; (CPUID function structure).
;
%define OVMF_SECTION_TYPE_CPUID 0x3
OvmfPkg/ResetVector: introduce SEV metadata descriptor for VMM use BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275 The OvmfPkgX86 build reserves memory regions in MEMFD. The memory regions get accessed in the SEC phase. AMD SEV-SNP require that the guest's private memory be accepted or validated before access. Introduce a Guided metadata structure that describes the reserved memory regions. The VMM can locate the metadata structure by iterating through the reset vector guid and process the areas based on the platform specific requirements. Cc: Michael Roth <michael.roth@amd.com> Cc: James Bottomley <jejb@linux.ibm.com> Cc: Min Xu <min.m.xu@intel.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org> Cc: Erdem Aktas <erdemaktas@google.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
2021-12-09 04:27:32 +01:00
ALIGN 16
TIMES (15 - ((OvmfSevGuidedStructureEnd - OvmfSevGuidedStructureStart + 15) % 16)) DB 0
OvmfSevGuidedStructureStart:
;
; OvmfSev metadata descriptor
;
OvmfSevMetadataGuid:
_DescriptorSev:
DB 'A','S','E','V' ; Signature
DD OvmfSevGuidedStructureEnd - _DescriptorSev ; Length
DD OVMF_SEV_METADATA_VERSION ; Version
DD (OvmfSevGuidedStructureEnd - _DescriptorSev - 16) / 12 ; Number of sections
OvmfPkg/ResetVector: pre-validate the data pages used in SEC phase BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275 An SEV-SNP guest requires that private memory (aka pages mapped encrypted) must be validated before being accessed. The validation process consist of the following sequence: 1) Set the memory encryption attribute in the page table (aka C-bit). Note: If the processor is in non-PAE mode, then all the memory accesses are considered private. 2) Add the memory range as private in the RMP table. This can be performed using the Page State Change VMGEXIT defined in the GHCB specification. 3) Use the PVALIDATE instruction to set the Validated Bit in the RMP table. During the guest creation time, the VMM encrypts the OVMF_CODE.fd using the SEV-SNP firmware provided LAUNCH_UPDATE_DATA command. In addition to encrypting the content, the command also validates the memory region. This allows us to execute the code without going through the validation sequence. During execution, the reset vector need to access some data pages (such as page tables, SevESWorkarea, Sec stack). The data pages are accessed as private memory. The data pages are not part of the OVMF_CODE.fd, so they were not validated during the guest creation. There are two approaches we can take to validate the data pages before the access: a) Enhance the OVMF reset vector code to validate the pages as described above (go through step 2 - 3). OR b) Validate the pages during the guest creation time. The SEV firmware provides a command which can be used by the VMM to validate the pages without affecting the measurement of the launch. Approach #b seems much simpler; it does not require any changes to the OVMF reset vector code. Update the OVMF metadata with the list of regions that must be pre-validated by the VMM before the boot. Cc: Michael Roth <michael.roth@amd.com> Cc: James Bottomley <jejb@linux.ibm.com> Cc: Min Xu <min.m.xu@intel.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org> Cc: Erdem Aktas <erdemaktas@google.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
2021-12-09 04:27:35 +01:00
; Region need to be pre-validated by the hypervisor
PreValidate1:
DD SNP_SEC_MEM_BASE_DESC_1
DD SNP_SEC_MEM_SIZE_DESC_1
DD OVMF_SECTION_TYPE_SNP_SEC_MEM
PreValidate2:
DD SNP_SEC_MEM_BASE_DESC_2
DD SNP_SEC_MEM_SIZE_DESC_2
DD OVMF_SECTION_TYPE_SNP_SEC_MEM
OvmfPkg: reserve SNP secrets page BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275 During the SNP guest launch sequence, a special secrets page needs to be inserted by the VMM. The PSP will populate the page; it will contain the VM Platform Communication Key (VMPCKs) used by the guest to send and receive secure messages to the PSP. The purpose of the secrets page in the SEV-SNP is different from the one used in SEV guests. In SEV, the secrets page contains the guest owner's private data after the remote attestation. Cc: Michael Roth <michael.roth@amd.com> Cc: James Bottomley <jejb@linux.ibm.com> Cc: Min Xu <min.m.xu@intel.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org> Cc: Erdem Aktas <erdemaktas@google.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Acked-by: Jiewen Yao <Jiewen.yao@intel.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
2021-12-09 04:27:33 +01:00
; SEV-SNP Secrets page
SevSnpSecrets:
DD SEV_SNP_SECRETS_BASE
DD SEV_SNP_SECRETS_SIZE
DD OVMF_SECTION_TYPE_SNP_SECRETS
OvmfPkg: reserve CPUID page BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275 Platform features and capabilities are traditionally discovered via the CPUID instruction. Hypervisors typically trap and emulate the CPUID instruction for a variety of reasons. There are some cases where incorrect CPUID information can potentially lead to a security issue. The SEV-SNP firmware provides a feature to filter the CPUID results through the PSP. The filtered CPUID values are saved on a special page for the guest to consume. Reserve a page in MEMFD that will contain the results of filtered CPUID values. Cc: Michael Roth <michael.roth@amd.com> Cc: James Bottomley <jejb@linux.ibm.com> Cc: Min Xu <min.m.xu@intel.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org> Cc: Erdem Aktas <erdemaktas@google.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Acked-by: Jiewen Yao <Jiewen.yao@intel.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
2021-12-09 04:27:34 +01:00
; CPUID values
CpuidSec:
DD CPUID_BASE
DD CPUID_SIZE
DD OVMF_SECTION_TYPE_CPUID
OvmfPkg/ResetVector: pre-validate the data pages used in SEC phase BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275 An SEV-SNP guest requires that private memory (aka pages mapped encrypted) must be validated before being accessed. The validation process consist of the following sequence: 1) Set the memory encryption attribute in the page table (aka C-bit). Note: If the processor is in non-PAE mode, then all the memory accesses are considered private. 2) Add the memory range as private in the RMP table. This can be performed using the Page State Change VMGEXIT defined in the GHCB specification. 3) Use the PVALIDATE instruction to set the Validated Bit in the RMP table. During the guest creation time, the VMM encrypts the OVMF_CODE.fd using the SEV-SNP firmware provided LAUNCH_UPDATE_DATA command. In addition to encrypting the content, the command also validates the memory region. This allows us to execute the code without going through the validation sequence. During execution, the reset vector need to access some data pages (such as page tables, SevESWorkarea, Sec stack). The data pages are accessed as private memory. The data pages are not part of the OVMF_CODE.fd, so they were not validated during the guest creation. There are two approaches we can take to validate the data pages before the access: a) Enhance the OVMF reset vector code to validate the pages as described above (go through step 2 - 3). OR b) Validate the pages during the guest creation time. The SEV firmware provides a command which can be used by the VMM to validate the pages without affecting the measurement of the launch. Approach #b seems much simpler; it does not require any changes to the OVMF reset vector code. Update the OVMF metadata with the list of regions that must be pre-validated by the VMM before the boot. Cc: Michael Roth <michael.roth@amd.com> Cc: James Bottomley <jejb@linux.ibm.com> Cc: Min Xu <min.m.xu@intel.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org> Cc: Erdem Aktas <erdemaktas@google.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
2021-12-09 04:27:35 +01:00
; Region need to be pre-validated by the hypervisor
PreValidate3:
DD SNP_SEC_MEM_BASE_DESC_3
DD SNP_SEC_MEM_SIZE_DESC_3
DD OVMF_SECTION_TYPE_SNP_SEC_MEM
OvmfPkg/ResetVector: introduce SEV metadata descriptor for VMM use BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275 The OvmfPkgX86 build reserves memory regions in MEMFD. The memory regions get accessed in the SEC phase. AMD SEV-SNP require that the guest's private memory be accepted or validated before access. Introduce a Guided metadata structure that describes the reserved memory regions. The VMM can locate the metadata structure by iterating through the reset vector guid and process the areas based on the platform specific requirements. Cc: Michael Roth <michael.roth@amd.com> Cc: James Bottomley <jejb@linux.ibm.com> Cc: Min Xu <min.m.xu@intel.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org> Cc: Erdem Aktas <erdemaktas@google.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
2021-12-09 04:27:32 +01:00
OvmfSevGuidedStructureEnd:
ALIGN 16