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OvmfPkg/BaseMemEncryptLib: use the SEV_STATUS MSR value from workarea

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BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3582

Improve the MemEncryptSev{Es,Snp}IsEnabled() to use the SEV_STATUS MSR
value saved in the workarea. Since workarea is valid until the PEI phase,
so, for the Dxe phase use the PcdConfidentialComputingGuestAttr to
determine which SEV technology is enabled.

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>
Acked-by: Jiewen Yao <jiewen.yao@intel.com>
This commit is contained in:
Brijesh Singh
2022-02-21 22:59:14 +08:00
committed by mergify[bot]
parent 63c50d3ff2
commit f1d1c337e7
6 changed files with 155 additions and 212 deletions
Download Patch File Download Diff File Expand all files Collapse all files

143
OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLibInternal.c
View File

@@ -17,82 +17,51 @@
#include <Register/Cpuid.h>
#include <Uefi/UefiBaseType.h>
STATIC BOOLEAN mSevStatus = FALSE;
STATIC BOOLEAN mSevEsStatus = FALSE;
STATIC BOOLEAN mSevSnpStatus = FALSE;
STATIC BOOLEAN mSevStatusChecked = FALSE;
STATIC UINT64 mSevEncryptionMask = 0;
STATIC BOOLEAN mSevEncryptionMaskSaved = FALSE;
/**
Reads and sets the status of SEV features.
Read the workarea to determine whether SEV is enabled. If enabled,
then return the SevEsWorkArea pointer.
**/
STATIC
VOID
SEC_SEV_ES_WORK_AREA *
EFIAPI
GetSevEsWorkArea (
VOID
)
{
OVMF_WORK_AREA *WorkArea;
WorkArea = (OVMF_WORK_AREA *)FixedPcdGet32 (PcdOvmfWorkAreaBase);
//
// If its not SEV guest then SevEsWorkArea is not valid.
//
if ((WorkArea == NULL) || (WorkArea->Header.GuestType != GUEST_TYPE_AMD_SEV)) {
return NULL;
}
return (SEC_SEV_ES_WORK_AREA *)FixedPcdGet32 (PcdSevEsWorkAreaBase);
}
/**
Read the SEV Status MSR value from the workarea
**/
STATIC
UINT32
EFIAPI
InternalMemEncryptSevStatus (
VOID
)
{
UINT32 RegEax;
MSR_SEV_STATUS_REGISTER Msr;
CPUID_MEMORY_ENCRYPTION_INFO_EAX Eax;
BOOLEAN ReadSevMsr;
SEC_SEV_ES_WORK_AREA *SevEsWorkArea;
SEC_SEV_ES_WORK_AREA *SevEsWorkArea;
ReadSevMsr = FALSE;
SevEsWorkArea = (SEC_SEV_ES_WORK_AREA *)FixedPcdGet32 (PcdSevEsWorkAreaBase);
if ((SevEsWorkArea != NULL) && (SevEsWorkArea->EncryptionMask != 0)) {
//
// The MSR has been read before, so it is safe to read it again and avoid
// having to validate the CPUID information.
//
ReadSevMsr = TRUE;
} else {
//
// Check if memory encryption leaf exist
//
AsmCpuid (CPUID_EXTENDED_FUNCTION, &RegEax, NULL, NULL, NULL);
if (RegEax >= CPUID_MEMORY_ENCRYPTION_INFO) {
//
// CPUID Fn8000_001F[EAX] Bit 1 (Sev supported)
//
AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, &Eax.Uint32, NULL, NULL, NULL);
if (Eax.Bits.SevBit) {
ReadSevMsr = TRUE;
}
}
SevEsWorkArea = GetSevEsWorkArea ();
if (SevEsWorkArea == NULL) {
return 0;
}
if (ReadSevMsr) {
//
// Check MSR_0xC0010131 Bit 0 (Sev Enabled)
//
Msr.Uint32 = AsmReadMsr32 (MSR_SEV_STATUS);
if (Msr.Bits.SevBit) {
mSevStatus = TRUE;
}
//
// Check MSR_0xC0010131 Bit 1 (Sev-Es Enabled)
//
if (Msr.Bits.SevEsBit) {
mSevEsStatus = TRUE;
}
//
// Check MSR_0xC0010131 Bit 2 (Sev-Snp Enabled)
//
if (Msr.Bits.SevSnpBit) {
mSevSnpStatus = TRUE;
}
}
mSevStatusChecked = TRUE;
return (UINT32)(UINTN)SevEsWorkArea->SevStatusMsrValue;
}
/**
@@ -107,11 +76,11 @@ MemEncryptSevSnpIsEnabled (
VOID
)
{
if (!mSevStatusChecked) {
InternalMemEncryptSevStatus ();
}
MSR_SEV_STATUS_REGISTER Msr;
return mSevSnpStatus;
Msr.Uint32 = InternalMemEncryptSevStatus ();
return Msr.Bits.SevSnpBit ? TRUE : FALSE;
}
/**
@@ -126,11 +95,11 @@ MemEncryptSevEsIsEnabled (
VOID
)
{
if (!mSevStatusChecked) {
InternalMemEncryptSevStatus ();
}
MSR_SEV_STATUS_REGISTER Msr;
return mSevEsStatus;
Msr.Uint32 = InternalMemEncryptSevStatus ();
return Msr.Bits.SevEsBit ? TRUE : FALSE;
}
/**
@@ -145,11 +114,11 @@ MemEncryptSevIsEnabled (
VOID
)
{
if (!mSevStatusChecked) {
InternalMemEncryptSevStatus ();
}
MSR_SEV_STATUS_REGISTER Msr;
return mSevStatus;
Msr.Uint32 = InternalMemEncryptSevStatus ();
return Msr.Bits.SevBit ? TRUE : FALSE;
}
/**
@@ -163,24 +132,12 @@ MemEncryptSevGetEncryptionMask (
VOID
)
{
if (!mSevEncryptionMaskSaved) {
SEC_SEV_ES_WORK_AREA *SevEsWorkArea;
SEC_SEV_ES_WORK_AREA *SevEsWorkArea;
SevEsWorkArea = (SEC_SEV_ES_WORK_AREA *)FixedPcdGet32 (PcdSevEsWorkAreaBase);
if (SevEsWorkArea != NULL) {
mSevEncryptionMask = SevEsWorkArea->EncryptionMask;
} else {
CPUID_MEMORY_ENCRYPTION_INFO_EBX Ebx;
//
// CPUID Fn8000_001F[EBX] Bit 0:5 (memory encryption bit position)
//
AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, NULL, &Ebx.Uint32, NULL, NULL);
mSevEncryptionMask = LShiftU64 (1, Ebx.Bits.PtePosBits);
}
mSevEncryptionMaskSaved = TRUE;
SevEsWorkArea = GetSevEsWorkArea ();
if (SevEsWorkArea == NULL) {
return 0;
}
return mSevEncryptionMask;
return SevEsWorkArea->EncryptionMask;
}