The SEV-SNP Confidential Computing blob contains metadata that should
remain accessible for the life of the guest. Allocate it as
EfiACPIReclaimMemory to ensure the memory isn't overwritten by the guest
operating system later.
Reported-by: Dov Murik <dovmurik@linux.ibm.com>
Suggested-by: Dov Murik <dovmurik@linux.ibm.com>
Reviewed-by: Dov Murik <dovmurik@linux.ibm.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
---
OvmfPkg/AmdSevDxe/AmdSevDxe.c | 62 +++++++++++++++++++++++++++--------
1 file changed, 48 insertions(+), 14 deletions(-)
diff --git a/OvmfPkg/AmdSevDxe/AmdSevDxe.c b/OvmfPkg/AmdSevDxe/AmdSevDxe.c
index a726498e27..7250cc90e5 100644
--- a/OvmfPkg/AmdSevDxe/AmdSevDxe.c
+++ b/OvmfPkg/AmdSevDxe/AmdSevDxe.c
@@ -28,15 +28,36 @@
// Present, initialized, tested bits defined in MdeModulePkg/Core/Dxe/DxeMain.h
#define EFI_MEMORY_INTERNAL_MASK 0x0700000000000000ULL
-STATIC CONFIDENTIAL_COMPUTING_SNP_BLOB_LOCATION mSnpBootDxeTable = {
- SIGNATURE_32 ('A', 'M', 'D', 'E'),
- 1,
- 0,
- (UINT64)(UINTN)FixedPcdGet32 (PcdOvmfSnpSecretsBase),
- FixedPcdGet32 (PcdOvmfSnpSecretsSize),
- (UINT64)(UINTN)FixedPcdGet32 (PcdOvmfCpuidBase),
- FixedPcdGet32 (PcdOvmfCpuidSize),
-};
+STATIC
+EFI_STATUS
+AllocateConfidentialComputingBlob (
+ OUT CONFIDENTIAL_COMPUTING_SNP_BLOB_LOCATION **CcBlobPtr
+ )
+{
+ EFI_STATUS Status;
+ CONFIDENTIAL_COMPUTING_SNP_BLOB_LOCATION *CcBlob;
+
+ Status = gBS->AllocatePool (
+ EfiACPIReclaimMemory,
+ sizeof (CONFIDENTIAL_COMPUTING_SNP_BLOB_LOCATION),
+ (VOID **)&CcBlob
+ );
+ if (EFI_ERROR (Status)) {
+ return Status;
+ }
+
+ CcBlob->Header = SIGNATURE_32 ('A', 'M', 'D', 'E');
+ CcBlob->Version = 1;
+ CcBlob->Reserved1 = 0;
+ CcBlob->SecretsPhysicalAddress = (UINT64)(UINTN)FixedPcdGet32 (PcdOvmfSnpSecretsBase);
+ CcBlob->SecretsSize = FixedPcdGet32 (PcdOvmfSnpSecretsSize);
+ CcBlob->CpuidPhysicalAddress = (UINT64)(UINTN)FixedPcdGet32 (PcdOvmfCpuidBase);
+ CcBlob->CpuidLSize = FixedPcdGet32 (PcdOvmfCpuidSize);
+
+ *CcBlobPtr = CcBlob;
+
+ return EFI_SUCCESS;
+}
STATIC EFI_HANDLE mAmdSevDxeHandle = NULL;
@@ -177,10 +198,11 @@ AmdSevDxeEntryPoint (
IN EFI_SYSTEM_TABLE *SystemTable
)
{
- EFI_STATUS Status;
- EFI_GCD_MEMORY_SPACE_DESCRIPTOR *AllDescMap;
- UINTN NumEntries;
- UINTN Index;
+ EFI_STATUS Status;
+ EFI_GCD_MEMORY_SPACE_DESCRIPTOR *AllDescMap;
+ UINTN NumEntries;
+ UINTN Index;
+ CONFIDENTIAL_COMPUTING_SNP_BLOB_LOCATION *SnpBootDxeTable;
//
// Do nothing when SEV is not enabled
@@ -286,6 +308,18 @@ AmdSevDxeEntryPoint (
}
}
+ Status = AllocateConfidentialComputingBlob (&SnpBootDxeTable);
+ if (EFI_ERROR (Status)) {
+ DEBUG ((
+ DEBUG_ERROR,
+ "%a: AllocateConfidentialComputingBlob(): %r\n",
+ __FUNCTION__,
+ Status
+ ));
+ ASSERT (FALSE);
+ CpuDeadLoop ();
+ }
+
if (MemEncryptSevSnpIsEnabled ()) {
//
// Memory acceptance began being required in SEV-SNP, so install the
@@ -323,7 +357,7 @@ AmdSevDxeEntryPoint (
//
return gBS->InstallConfigurationTable (
&gConfidentialComputingSevSnpBlobGuid,
- &mSnpBootDxeTable
+ SnpBootDxeTable
);
}
--
2.25.1
-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#101245): https://edk2.groups.io/g/devel/message/101245
Mute This Topic: https://groups.io/mt/97638492/1787277
Group Owner: devel+owner@edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [importer@patchew.org]
-=-=-=-=-=-=-=-=-=-=-=-On Wed, Mar 15, 2023 at 04:57:44PM -0500, Michael Roth wrote: > The SEV-SNP Confidential Computing blob contains metadata that should > remain accessible for the life of the guest. Allocate it as > EfiACPIReclaimMemory to ensure the memory isn't overwritten by the guest > operating system later. > > Reported-by: Dov Murik <dovmurik@linux.ibm.com> > Suggested-by: Dov Murik <dovmurik@linux.ibm.com> > Reviewed-by: Dov Murik <dovmurik@linux.ibm.com> > Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> > Signed-off-by: Michael Roth <michael.roth@amd.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#101417): https://edk2.groups.io/g/devel/message/101417 Mute This Topic: https://groups.io/mt/97638492/1787277 Group Owner: devel+owner@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [importer@patchew.org] -=-=-=-=-=-=-=-=-=-=-=-
© 2016 - 2025 Red Hat, Inc.