[PATCH v7 15/31] OvmfPkg/BaseMemEncryptSevLib: skip the pre-validated system RAM


Brijesh Singh
 

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275

The MemEncryptSevSnpPreValidateSystemRam() is used for pre-validating the
system RAM. As the boot progress, each phase validates a fixed region of
the RAM. In the PEI phase, the PlatformPei detects all the available RAM
and calls to pre-validate the detected system RAM.

While validating the system RAM in PEI phase, we must skip previously
validated system RAM to avoid the double validation.

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>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
.../PeiMemEncryptSevLib.inf | 20 ++++
.../X64/PeiSnpSystemRamValidate.c | 102 +++++++++++++++++-
2 files changed, 121 insertions(+), 1 deletion(-)

diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
index 0402e49a1028..1cc9dd6691a2 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
@@ -57,4 +57,24 @@ [FeaturePcd]
gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire

[FixedPcd]
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidSize
gUefiCpuPkgTokenSpaceGuid.PcdSevEsWorkAreaBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbSize
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsSize
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBackupBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBackupSize
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbPageTableBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbPageTableSize
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesSize
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamSize
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaSize
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfLockBoxStorageBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfLockBoxStorageSize
+ gEfiMdePkgTokenSpaceGuid.PcdGuidedExtractHandlerTableAddress
+ gUefiOvmfPkgTokenSpaceGuid.PcdGuidedExtractHandlerTableSize
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c
index 64aab7f45b6d..eae7a31773a4 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c
@@ -14,6 +14,81 @@

#include "SnpPageStateChange.h"

+typedef struct {
+ UINT64 StartAddress;
+ UINT64 EndAddress;
+} SNP_PRE_VALIDATED_RANGE;
+
+STATIC SNP_PRE_VALIDATED_RANGE mPreValidatedRange[] = {
+ // The below address range was part of the OVMF metadata, and range
+ // should be pre-validated by the Hypervisor.
+ {
+ FixedPcdGet32 (PcdOvmfSecPageTablesBase),
+ FixedPcdGet32 (PcdOvmfSecPageTablesBase) + FixedPcdGet32 (PcdOvmfSecPageTablesSize),
+ },
+ {
+ FixedPcdGet32 (PcdOvmfLockBoxStorageBase),
+ FixedPcdGet32 (PcdOvmfLockBoxStorageBase) + FixedPcdGet32 (PcdOvmfLockBoxStorageSize),
+ },
+ {
+ FixedPcdGet64 (PcdGuidedExtractHandlerTableAddress),
+ FixedPcdGet64 (PcdGuidedExtractHandlerTableAddress) + FixedPcdGet32 (PcdGuidedExtractHandlerTableSize)
+ },
+ {
+ FixedPcdGet32 (PcdOvmfSecGhcbPageTableBase),
+ FixedPcdGet32 (PcdOvmfSecGhcbPageTableBase) + FixedPcdGet32 (PcdOvmfSecGhcbPageTableSize),
+ },
+ {
+ FixedPcdGet32 (PcdOvmfSecGhcbBase),
+ FixedPcdGet32 (PcdOvmfSecGhcbBase) + FixedPcdGet32 (PcdOvmfSecGhcbSize),
+ },
+ {
+ FixedPcdGet32 (PcdOvmfWorkAreaBase),
+ FixedPcdGet32 (PcdOvmfWorkAreaBase) + FixedPcdGet32 (PcdOvmfWorkAreaSize),
+ },
+ {
+ FixedPcdGet32 (PcdOvmfSecGhcbBackupBase),
+ FixedPcdGet32 (PcdOvmfSecGhcbBackupBase) + FixedPcdGet32 (PcdOvmfSecGhcbBackupSize),
+ },
+ {
+ FixedPcdGet32 (PcdOvmfSnpSecretsBase),
+ FixedPcdGet32 (PcdOvmfSnpSecretsBase) + FixedPcdGet32 (PcdOvmfSnpSecretsSize),
+ },
+ {
+ FixedPcdGet32 (PcdOvmfCpuidBase),
+ FixedPcdGet32 (PcdOvmfCpuidBase) + FixedPcdGet32 (PcdOvmfCpuidSize),
+ },
+ {
+ FixedPcdGet32 (PcdOvmfSecPeiTempRamBase),
+ FixedPcdGet32 (PcdOvmfSecPeiTempRamBase) + FixedPcdGet32 (PcdOvmfSecPeiTempRamSize),
+ },
+};
+
+STATIC
+BOOLEAN
+DetectPreValidatedOverLap (
+ IN PHYSICAL_ADDRESS StartAddress,
+ IN PHYSICAL_ADDRESS EndAddress,
+ OUT SNP_PRE_VALIDATED_RANGE *OverlapRange
+ )
+{
+ UINTN i;
+
+ //
+ // Check if the specified address range exist in pre-validated array.
+ //
+ for (i = 0; i < ARRAY_SIZE (mPreValidatedRange); i++) {
+ if ((mPreValidatedRange[i].StartAddress < EndAddress) &&
+ (StartAddress < mPreValidatedRange[i].EndAddress)) {
+ OverlapRange->StartAddress = mPreValidatedRange[i].StartAddress;
+ OverlapRange->EndAddress = mPreValidatedRange[i].EndAddress;
+ return TRUE;
+ }
+ }
+
+ return FALSE;
+}
+
/**
Pre-validate the system RAM when SEV-SNP is enabled in the guest VM.

@@ -28,9 +103,34 @@ MemEncryptSevSnpPreValidateSystemRam (
IN UINTN NumPages
)
{
+ PHYSICAL_ADDRESS EndAddress;
+ SNP_PRE_VALIDATED_RANGE OverlapRange;
+
if (!MemEncryptSevSnpIsEnabled ()) {
return;
}

- InternalSetPageState (BaseAddress, NumPages, SevSnpPagePrivate, TRUE);
+ EndAddress = BaseAddress + EFI_PAGES_TO_SIZE (NumPages);
+
+ while (BaseAddress < EndAddress) {
+ //
+ // Check if the range overlaps with the pre-validated ranges.
+ //
+ if (DetectPreValidatedOverLap (BaseAddress, EndAddress, &OverlapRange)) {
+ // Validate the non-overlap regions.
+ if (BaseAddress < OverlapRange.StartAddress) {
+ NumPages = EFI_SIZE_TO_PAGES (OverlapRange.StartAddress - BaseAddress);
+
+ InternalSetPageState (BaseAddress, NumPages, SevSnpPagePrivate, TRUE);
+ }
+
+ BaseAddress = OverlapRange.EndAddress;
+ continue;
+ }
+
+ // Validate the remaining pages.
+ NumPages = EFI_SIZE_TO_PAGES (EndAddress - BaseAddress);
+ InternalSetPageState (BaseAddress, NumPages, SevSnpPagePrivate, TRUE);
+ BaseAddress = EndAddress;
+ }
}
--
2.17.1