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OvmfPkg/MemEncryptSevLib: Add an interface to retrieve the encryption mask

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BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3108

To ensure that we always use a validated encryption mask for an SEV-ES
guest, create a new interface in the MemEncryptSevLib library to return
the encryption mask. This can be used in place of the multiple locations
where CPUID is used to retrieve the value (which would require validation
again) and allows the validated mask to be returned.

The PEI phase will use the value from the SEV-ES work area. Since the
SEV-ES work area isn't valid in the DXE phase, the DXE phase will use the
PcdPteMemoryEncryptionAddressOrMask PCD which is set during PEI.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Rebecca Cran <rebecca@bsdio.com>
Cc: Peter Grehan <grehan@freebsd.org>
Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Julien Grall <julien@xen.org>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <e12044dc01b21e6fc2e9535760ddf3a38a142a71.1610045305.git.thomas.lendacky@amd.com>
This commit is contained in:
Tom Lendacky
2021-01-07 12:48:16 -06:00
committed by mergify[bot]
parent 3b32be7e71
commit b97dc4b92b
12 changed files with 400 additions and 104 deletions
Download Patch File Download Diff File Expand all files Collapse all files

94
OvmfPkg/Library/BaseMemEncryptSevLib/MemEncryptSevLibInternal.c
View File

@ -2,7 +2,7 @@
Secure Encrypted Virtualization (SEV) library helper function
Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
Copyright (c) 2017 - 2020, AMD Incorporated. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
@ -12,102 +12,10 @@
#include <Library/DebugLib.h>
#include <Library/MemEncryptSevLib.h>
#include <Library/PcdLib.h>
#include <Register/Amd/Cpuid.h>
#include <Register/Amd/Msr.h>
#include <Register/Cpuid.h>
#include <Register/QemuSmramSaveStateMap.h>
#include <Register/SmramSaveStateMap.h>
#include <Uefi/UefiBaseType.h>
STATIC BOOLEAN mSevStatus = FALSE;
STATIC BOOLEAN mSevEsStatus = FALSE;
STATIC BOOLEAN mSevStatusChecked = FALSE;
/**
Reads and sets the status of SEV features.
**/
STATIC
VOID
EFIAPI
InternalMemEncryptSevStatus (
VOID
)
{
UINT32 RegEax;
MSR_SEV_STATUS_REGISTER Msr;
CPUID_MEMORY_ENCRYPTION_INFO_EAX Eax;
//
// 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) {
//
// 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;
}
}
}
mSevStatusChecked = TRUE;
}
/**
Returns a boolean to indicate whether SEV-ES is enabled.
@retval TRUE SEV-ES is enabled
@retval FALSE SEV-ES is not enabled
**/
BOOLEAN
EFIAPI
MemEncryptSevEsIsEnabled (
VOID
)
{
if (!mSevStatusChecked) {
InternalMemEncryptSevStatus ();
}
return mSevEsStatus;
}
/**
Returns a boolean to indicate whether SEV is enabled.
@retval TRUE SEV is enabled
@retval FALSE SEV is not enabled
**/
BOOLEAN
EFIAPI
MemEncryptSevIsEnabled (
VOID
)
{
if (!mSevStatusChecked) {
InternalMemEncryptSevStatus ();
}
return mSevStatus;
}
/**
Locate the page range that covers the initial (pre-SMBASE-relocation) SMRAM
Save State Map.