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/** @file
Copyright (c) 2025, Advanced Micro Devices, Inc. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <Library/BaseLib.h>
#include <Register/Amd/Cpuid.h>
#include <Register/Amd/SevSnpMsr.h>
#include <Register/Intel/Cpuid.h>
/**
Probe if running as some kind of SEV guest.
@return FALSE Not running as a guest under any kind of SEV
@return TRUE Running as a guest under any kind of SEV
**/
BOOLEAN
EFIAPI
SevGuestIsEnabled (
VOID
)
{
UINT32 MaxExtendedLeaf;
MSR_SEV_STATUS_REGISTER SevStatus;
CPUID_MEMORY_ENCRYPTION_INFO_EAX MemoryEncryptionInfoEax;
// Check max extended CPUID leaf
AsmCpuid (CPUID_EXTENDED_FUNCTION, &MaxExtendedLeaf, NULL, NULL, NULL);
if (MaxExtendedLeaf < CPUID_MEMORY_ENCRYPTION_INFO) {
return FALSE;
}
// Check SEV support
AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, &MemoryEncryptionInfoEax.Uint32, NULL, NULL, NULL);
if (MemoryEncryptionInfoEax.Bits.SevBit == 0) {
return FALSE;
}
// Read SEV_STATUS MSR
SevStatus.Uint64 = AsmReadMsr64 (MSR_SEV_STATUS);
return (SevStatus.Bits.SevBit | SevStatus.Bits.SevEsBit | SevStatus.Bits.SevSnpBit) ? TRUE : FALSE;
}
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