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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

141
OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLibInternal.c
View File

@@ -16,83 +16,84 @@
#include <Register/Amd/Msr.h>
#include <Register/Cpuid.h>
#include <Uefi/UefiBaseType.h>
#include <ConfidentialComputingGuestAttr.h>
STATIC BOOLEAN mSevStatus = FALSE;
STATIC BOOLEAN mSevEsStatus = FALSE;
STATIC BOOLEAN mSevSnpStatus = FALSE;
STATIC BOOLEAN mSevStatusChecked = FALSE;
STATIC UINT64 mCurrentAttr = 0;
STATIC BOOLEAN mCurrentAttrRead = FALSE;
STATIC UINT64 mSevEncryptionMask = 0;
STATIC BOOLEAN mSevEncryptionMaskSaved = FALSE;
/**
Reads and sets the status of SEV features.
The function check if the specified Attr is set.
**/
@param[in] CurrentAttr The current attribute.
@param[in] Attr The attribute to check.
@retval TRUE The specified Attr is set.
@retval FALSE The specified Attr is not set.
**/
STATIC
VOID
EFIAPI
InternalMemEncryptSevStatus (
VOID
BOOLEAN
AmdMemEncryptionAttrCheck (
IN UINT64 CurrentAttr,
IN CONFIDENTIAL_COMPUTING_GUEST_ATTR Attr
)
{
UINT32 RegEax;
MSR_SEV_STATUS_REGISTER Msr;
CPUID_MEMORY_ENCRYPTION_INFO_EAX Eax;
BOOLEAN ReadSevMsr;
UINT64 EncryptionMask;
ReadSevMsr = FALSE;
EncryptionMask = PcdGet64 (PcdPteMemoryEncryptionAddressOrMask);
if (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) {
switch (Attr) {
case CCAttrAmdSev:
//
// CPUID Fn8000_001F[EAX] Bit 1 (Sev supported)
// SEV is automatically enabled if SEV-ES or SEV-SNP is active.
//
AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, &Eax.Uint32, NULL, NULL, NULL);
return CurrentAttr >= CCAttrAmdSev;
case CCAttrAmdSevEs:
//
// SEV-ES is automatically enabled if SEV-SNP is active.
//
return CurrentAttr >= CCAttrAmdSevEs;
case CCAttrAmdSevSnp:
return CurrentAttr == CCAttrAmdSevSnp;
default:
return FALSE;
}
}
if (Eax.Bits.SevBit) {
ReadSevMsr = TRUE;
}
}
/**
Check if the specified confidential computing attribute is active.
@param[in] Attr The attribute to check.
@retval TRUE The specified Attr is active.
@retval FALSE The specified Attr is not active.
**/
STATIC
BOOLEAN
EFIAPI
ConfidentialComputingGuestHas (
IN CONFIDENTIAL_COMPUTING_GUEST_ATTR Attr
)
{
//
// Get the current CC attribute.
//
// We avoid reading the PCD on every check because this routine could be indirectly
// called during the virtual pointer conversion. And its not safe to access the
// PCDs during the virtual pointer conversion.
//
if (!mCurrentAttrRead) {
mCurrentAttr = PcdGet64 (PcdConfidentialComputingGuestAttr);
mCurrentAttrRead = TRUE;
}
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;
}
//
// If attr is for the AMD group then call AMD specific checks.
//
if (((RShiftU64 (mCurrentAttr, 8)) & 0xff) == 1) {
return AmdMemEncryptionAttrCheck (mCurrentAttr, Attr);
}
mSevStatusChecked = TRUE;
return (mCurrentAttr == Attr);
}
/**
@@ -107,11 +108,7 @@ MemEncryptSevSnpIsEnabled (
VOID
)
{
if (!mSevStatusChecked) {
InternalMemEncryptSevStatus ();
}
return mSevSnpStatus;
return ConfidentialComputingGuestHas (CCAttrAmdSevSnp);
}
/**
@@ -126,11 +123,7 @@ MemEncryptSevEsIsEnabled (
VOID
)
{
if (!mSevStatusChecked) {
InternalMemEncryptSevStatus ();
}
return mSevEsStatus;
return ConfidentialComputingGuestHas (CCAttrAmdSevEs);
}
/**
@@ -145,11 +138,7 @@ MemEncryptSevIsEnabled (
VOID
)
{
if (!mSevStatusChecked) {
InternalMemEncryptSevStatus ();
}
return mSevStatus;
return ConfidentialComputingGuestHas (CCAttrAmdSev);
}
/**