* [PATCH v2 1/2] OvmfPkg/ResetVector: cache the SEV status MSR value in workarea
2022-02-21 14:59 [PATCH v2 0/2] SEV BaseMemEncryptLib cleanup Brijesh Singh
@ 2022-02-21 14:59 ` Brijesh Singh
2022-02-21 14:59 ` [PATCH v2 2/2] OvmfPkg/BaseMemEncryptLib: use the SEV_STATUS MSR value from workarea Brijesh Singh
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Brijesh Singh @ 2022-02-21 14:59 UTC (permalink / raw)
To: devel
Cc: James Bottomley, Min Xu, Jiewen Yao, Tom Lendacky, Jordan Justen,
Ard Biesheuvel, Erdem Aktas, Michael Roth, Gerd Hoffmann,
aaron.young, Brijesh Singh
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3582
In order to probe the SEV feature the BaseMemEncryptLib and Reset vector
reads the SEV_STATUS MSR. Cache the value on the first read in the
workarea. In the next patches the value saved in the workarea will
be used by the BaseMemEncryptLib. This not only eliminates the extra
MSR reads it also helps cleaning up the code in BaseMemEncryptLib.
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>
---
OvmfPkg/Include/WorkArea.h | 12 +++++--
OvmfPkg/Sec/AmdSev.c | 2 +-
OvmfPkg/ResetVector/Ia32/AmdSev.asm | 38 +++++++++++++--------
OvmfPkg/ResetVector/Ia32/Flat32ToFlat64.asm | 3 +-
OvmfPkg/ResetVector/ResetVector.nasmb | 3 ++
5 files changed, 39 insertions(+), 19 deletions(-)
diff --git a/OvmfPkg/Include/WorkArea.h b/OvmfPkg/Include/WorkArea.h
index ce60d97aa886..d982e026def7 100644
--- a/OvmfPkg/Include/WorkArea.h
+++ b/OvmfPkg/Include/WorkArea.h
@@ -46,12 +46,20 @@ typedef struct _CONFIDENTIAL_COMPUTING_WORK_AREA_HEADER {
// any changes must stay in sync with its usage.
//
typedef struct _SEC_SEV_ES_WORK_AREA {
- UINT8 SevEsEnabled;
- UINT8 Reserved1[7];
+ //
+ // Hold the SevStatus MSR value read by OvmfPkg/ResetVector/Ia32/AmdSev.c
+ //
+ UINT64 SevStatusMsrValue;
UINT64 RandomData;
UINT64 EncryptionMask;
+
+ //
+ // Indicator that the VC handler is called. It is used during the SevFeature
+ // detection in OvmfPkg/ResetVector/Ia32/AmdSev.c
+ //
+ UINT8 ReceivedVc;
} SEC_SEV_ES_WORK_AREA;
//
diff --git a/OvmfPkg/Sec/AmdSev.c b/OvmfPkg/Sec/AmdSev.c
index 499d0c27d8fa..d8fd35650d7d 100644
--- a/OvmfPkg/Sec/AmdSev.c
+++ b/OvmfPkg/Sec/AmdSev.c
@@ -278,7 +278,7 @@ SevEsIsEnabled (
SevEsWorkArea = (SEC_SEV_ES_WORK_AREA *)FixedPcdGet32 (PcdSevEsWorkAreaBase);
- return (SevEsWorkArea->SevEsEnabled != 0);
+ return ((SevEsWorkArea->SevStatusMsrValue & BIT1) != 0);
}
/**
diff --git a/OvmfPkg/ResetVector/Ia32/AmdSev.asm b/OvmfPkg/ResetVector/Ia32/AmdSev.asm
index 1f827da3b929..864d68385342 100644
--- a/OvmfPkg/ResetVector/Ia32/AmdSev.asm
+++ b/OvmfPkg/ResetVector/Ia32/AmdSev.asm
@@ -157,8 +157,9 @@ SevClearPageEncMaskForGhcbPage:
jnz SevClearPageEncMaskForGhcbPageExit
; Check if SEV-ES is enabled
- cmp byte[SEV_ES_WORK_AREA], 1
- jnz SevClearPageEncMaskForGhcbPageExit
+ mov ecx, 1
+ bt [SEV_ES_WORK_AREA_STATUS_MSR], ecx
+ jnc SevClearPageEncMaskForGhcbPageExit
;
; The initial GHCB will live at GHCB_BASE and needs to be un-encrypted.
@@ -219,12 +220,16 @@ GetSevCBitMaskAbove31Exit:
; If SEV is disabled then EAX will be zero.
;
CheckSevFeatures:
- ; Set the first byte of the workarea to zero to communicate to the SEC
- ; phase that SEV-ES is not enabled. If SEV-ES is enabled, the CPUID
- ; instruction will trigger a #VC exception where the first byte of the
- ; workarea will be set to one or, if CPUID is not being intercepted,
- ; the MSR check below will set the first byte of the workarea to one.
- mov byte[SEV_ES_WORK_AREA], 0
+ ;
+ ; Clear the workarea, if SEV is enabled then later part of routine
+ ; will populate the workarea fields.
+ ;
+ mov ecx, SEV_ES_WORK_AREA_SIZE
+ mov eax, SEV_ES_WORK_AREA
+ClearSevEsWorkArea:
+ mov byte [eax], 0
+ inc eax
+ loop ClearSevEsWorkArea
;
; Set up exception handlers to check for SEV-ES
@@ -265,6 +270,10 @@ CheckSevFeatures:
; Set the work area header to indicate that the SEV is enabled
mov byte[WORK_AREA_GUEST_TYPE], 1
+ ; Save the SevStatus MSR value in the workarea
+ mov [SEV_ES_WORK_AREA_STATUS_MSR], eax
+ mov [SEV_ES_WORK_AREA_STATUS_MSR + 4], edx
+
; Check for SEV-ES memory encryption feature:
; CPUID Fn8000_001F[EAX] - Bit 3
; CPUID raises a #VC exception if running as an SEV-ES guest
@@ -280,10 +289,6 @@ CheckSevFeatures:
bt eax, 1
jnc GetSevEncBit
- ; Set the first byte of the workarea to one to communicate to the SEC
- ; phase that SEV-ES is enabled.
- mov byte[SEV_ES_WORK_AREA], 1
-
GetSevEncBit:
; Get pte bit position to enable memory encryption
; CPUID Fn8000_001F[EBX] - Bits 5:0
@@ -313,7 +318,10 @@ NoSev:
;
; Perform an SEV-ES sanity check by seeing if a #VC exception occurred.
;
- cmp byte[SEV_ES_WORK_AREA], 0
+ ; If SEV-ES is enabled, the CPUID instruction will trigger a #VC exception
+ ; where the RECEIVED_VC offset in the workarea will be set to one.
+ ;
+ cmp byte[SEV_ES_WORK_AREA_RECEIVED_VC], 0
jz NoSevPass
;
@@ -407,9 +415,9 @@ SevEsIdtVmmComm:
; If we're here, then we are an SEV-ES guest and this
; was triggered by a CPUID instruction
;
- ; Set the first byte of the workarea to one to communicate that
+ ; Set the recievedVc field in the workarea to communicate that
; a #VC was taken.
- mov byte[SEV_ES_WORK_AREA], 1
+ mov byte[SEV_ES_WORK_AREA_RECEIVED_VC], 1
pop ecx ; Error code
cmp ecx, 0x72 ; Be sure it was CPUID
diff --git a/OvmfPkg/ResetVector/Ia32/Flat32ToFlat64.asm b/OvmfPkg/ResetVector/Ia32/Flat32ToFlat64.asm
index eb3546668ef8..c5c683ebed3e 100644
--- a/OvmfPkg/ResetVector/Ia32/Flat32ToFlat64.asm
+++ b/OvmfPkg/ResetVector/Ia32/Flat32ToFlat64.asm
@@ -42,7 +42,8 @@ Transition32FlatTo64Flat:
;
xor ebx, ebx
- cmp byte[SEV_ES_WORK_AREA], 0
+ mov ecx, 1
+ bt [SEV_ES_WORK_AREA_STATUS_MSR], ecx
jz EnablePaging
;
diff --git a/OvmfPkg/ResetVector/ResetVector.nasmb b/OvmfPkg/ResetVector/ResetVector.nasmb
index cc364748b592..9421f4818907 100644
--- a/OvmfPkg/ResetVector/ResetVector.nasmb
+++ b/OvmfPkg/ResetVector/ResetVector.nasmb
@@ -100,8 +100,11 @@
%define GHCB_BASE (FixedPcdGet32 (PcdOvmfSecGhcbBase))
%define GHCB_SIZE (FixedPcdGet32 (PcdOvmfSecGhcbSize))
%define SEV_ES_WORK_AREA (FixedPcdGet32 (PcdSevEsWorkAreaBase))
+ %define SEV_ES_WORK_AREA_SIZE 25
+ %define SEV_ES_WORK_AREA_STATUS_MSR (FixedPcdGet32 (PcdSevEsWorkAreaBase))
%define SEV_ES_WORK_AREA_RDRAND (FixedPcdGet32 (PcdSevEsWorkAreaBase) + 8)
%define SEV_ES_WORK_AREA_ENC_MASK (FixedPcdGet32 (PcdSevEsWorkAreaBase) + 16)
+ %define SEV_ES_WORK_AREA_RECEIVED_VC (FixedPcdGet32 (PcdSevEsWorkAreaBase) + 24)
%define SEV_ES_VC_TOP_OF_STACK (FixedPcdGet32 (PcdOvmfSecPeiTempRamBase) + FixedPcdGet32 (PcdOvmfSecPeiTempRamSize))
%define SEV_SNP_SECRETS_BASE (FixedPcdGet32 (PcdOvmfSnpSecretsBase))
%define SEV_SNP_SECRETS_SIZE (FixedPcdGet32 (PcdOvmfSnpSecretsSize))
--
2.25.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v2 2/2] OvmfPkg/BaseMemEncryptLib: use the SEV_STATUS MSR value from workarea
2022-02-21 14:59 [PATCH v2 0/2] SEV BaseMemEncryptLib cleanup Brijesh Singh
2022-02-21 14:59 ` [PATCH v2 1/2] OvmfPkg/ResetVector: cache the SEV status MSR value in workarea Brijesh Singh
@ 2022-02-21 14:59 ` Brijesh Singh
2022-02-28 2:27 ` [PATCH v2 0/2] SEV BaseMemEncryptLib cleanup Yao, Jiewen
[not found] ` <16D7D2238C7EE163.30539@groups.io>
3 siblings, 0 replies; 5+ messages in thread
From: Brijesh Singh @ 2022-02-21 14:59 UTC (permalink / raw)
To: devel
Cc: James Bottomley, Min Xu, Jiewen Yao, Tom Lendacky, Jordan Justen,
Ard Biesheuvel, Erdem Aktas, Michael Roth, Gerd Hoffmann,
aaron.young, Brijesh Singh
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>
---
.../DxeMemEncryptSevLib.inf | 1 +
.../PeiMemEncryptSevLib.inf | 1 +
.../SecMemEncryptSevLib.inf | 1 +
.../DxeMemEncryptSevLibInternal.c | 145 ++++++++----------
.../PeiMemEncryptSevLibInternal.c | 139 ++++++-----------
.../SecMemEncryptSevLibInternal.c | 80 +++++-----
6 files changed, 155 insertions(+), 212 deletions(-)
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLib.inf b/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLib.inf
index f613bb314f5f..35b7d519d938 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLib.inf
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLib.inf
@@ -58,3 +58,4 @@ [FeaturePcd]
[Pcd]
gEfiMdeModulePkgTokenSpaceGuid.PcdPteMemoryEncryptionAddressOrMask
+ gEfiMdePkgTokenSpaceGuid.PcdConfidentialComputingGuestAttr
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
index 50c83859d7e7..714da3323765 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
@@ -58,6 +58,7 @@ [FeaturePcd]
[FixedPcd]
gUefiCpuPkgTokenSpaceGuid.PcdSevEsWorkAreaBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaBase
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfPeiMemFvBase
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesBase
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedEnd
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLib.inf b/OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLib.inf
index 939af0a91ea4..284e5acc1177 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLib.inf
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLib.inf
@@ -52,3 +52,4 @@ [LibraryClasses]
[FixedPcd]
gUefiCpuPkgTokenSpaceGuid.PcdSevEsWorkAreaBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaBase
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLibInternal.c b/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLibInternal.c
index 15fcd5529587..4aba0075b9e2 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLibInternal.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLibInternal.c
@@ -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
+BOOLEAN
+AmdMemEncryptionAttrCheck (
+ IN UINT64 CurrentAttr,
+ IN CONFIDENTIAL_COMPUTING_GUEST_ATTR Attr
+ )
+{
+ switch (Attr) {
+ case CCAttrAmdSev:
+ //
+ // SEV is automatically enabled if SEV-ES or SEV-SNP is active.
+ //
+ 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;
+ }
+}
+
+/**
+ 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
-VOID
+BOOLEAN
EFIAPI
-InternalMemEncryptSevStatus (
- VOID
+ConfidentialComputingGuestHas (
+ 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) {
- //
- // CPUID Fn8000_001F[EAX] Bit 1 (Sev supported)
- //
- AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, &Eax.Uint32, NULL, NULL, NULL);
-
- if (Eax.Bits.SevBit) {
- ReadSevMsr = TRUE;
- }
- }
+ //
+ // 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);
}
/**
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLibInternal.c b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLibInternal.c
index d68ff08c3ea6..3f8f91a5da12 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLibInternal.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLibInternal.c
@@ -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;
+/**
+ Read the workarea to determine whether SEV is enabled. If enabled,
+ then return the SevEsWorkArea pointer.
+
+ **/
+STATIC
+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;
+ }
-STATIC UINT64 mSevEncryptionMask = 0;
-STATIC BOOLEAN mSevEncryptionMaskSaved = FALSE;
+ return (SEC_SEV_ES_WORK_AREA *)FixedPcdGet32 (PcdSevEsWorkAreaBase);
+}
/**
- Reads and sets the status of SEV features.
+ Read the SEV Status MSR value from the workarea
**/
STATIC
-VOID
+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;
- }
- }
- }
-
- 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;
- }
+ SevEsWorkArea = GetSevEsWorkArea ();
+ if (SevEsWorkArea == NULL) {
+ return 0;
}
- 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;
}
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLibInternal.c b/OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLibInternal.c
index 5d912b2a4a5e..80aceba01bcf 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLibInternal.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLibInternal.c
@@ -18,7 +18,33 @@
#include <Uefi/UefiBaseType.h>
/**
- 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
+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
@@ -28,38 +54,14 @@ InternalMemEncryptSevStatus (
VOID
)
{
- UINT32 RegEax;
- 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;
}
- return ReadSevMsr ? AsmReadMsr32 (MSR_SEV_STATUS) : 0;
+ return (UINT32)(UINTN)SevEsWorkArea->SevStatusMsrValue;
}
/**
@@ -130,22 +132,14 @@ MemEncryptSevGetEncryptionMask (
VOID
)
{
- CPUID_MEMORY_ENCRYPTION_INFO_EBX Ebx;
- SEC_SEV_ES_WORK_AREA *SevEsWorkArea;
- UINT64 EncryptionMask;
+ SEC_SEV_ES_WORK_AREA *SevEsWorkArea;
- SevEsWorkArea = (SEC_SEV_ES_WORK_AREA *)FixedPcdGet32 (PcdSevEsWorkAreaBase);
- if (SevEsWorkArea != NULL) {
- EncryptionMask = SevEsWorkArea->EncryptionMask;
- } else {
- //
- // CPUID Fn8000_001F[EBX] Bit 0:5 (memory encryption bit position)
- //
- AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, NULL, &Ebx.Uint32, NULL, NULL);
- EncryptionMask = LShiftU64 (1, Ebx.Bits.PtePosBits);
+ SevEsWorkArea = GetSevEsWorkArea ();
+ if (SevEsWorkArea == NULL) {
+ return 0;
}
- return EncryptionMask;
+ return SevEsWorkArea->EncryptionMask;
}
/**
--
2.25.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH v2 0/2] SEV BaseMemEncryptLib cleanup
2022-02-21 14:59 [PATCH v2 0/2] SEV BaseMemEncryptLib cleanup Brijesh Singh
2022-02-21 14:59 ` [PATCH v2 1/2] OvmfPkg/ResetVector: cache the SEV status MSR value in workarea Brijesh Singh
2022-02-21 14:59 ` [PATCH v2 2/2] OvmfPkg/BaseMemEncryptLib: use the SEV_STATUS MSR value from workarea Brijesh Singh
@ 2022-02-28 2:27 ` Yao, Jiewen
[not found] ` <16D7D2238C7EE163.30539@groups.io>
3 siblings, 0 replies; 5+ messages in thread
From: Yao, Jiewen @ 2022-02-28 2:27 UTC (permalink / raw)
To: Brijesh Singh, devel@edk2.groups.io
Cc: James Bottomley, Xu, Min M, Tom Lendacky, Justen, Jordan L,
Ard Biesheuvel, Aktas, Erdem, Michael Roth, Gerd Hoffmann,
aaron.young@oracle.com
Acked-by: Jiewen Yao <Jiewen.yao@intel.com>
> -----Original Message-----
> From: Brijesh Singh <brijesh.singh@amd.com>
> Sent: Monday, February 21, 2022 10:59 PM
> To: devel@edk2.groups.io
> Cc: James Bottomley <jejb@linux.ibm.com>; Xu, Min M <min.m.xu@intel.com>;
> Yao, Jiewen <jiewen.yao@intel.com>; Tom Lendacky
> <thomas.lendacky@amd.com>; Justen, Jordan L <jordan.l.justen@intel.com>;
> Ard Biesheuvel <ardb+tianocore@kernel.org>; Aktas, Erdem
> <erdemaktas@google.com>; Michael Roth <Michael.Roth@amd.com>; Gerd
> Hoffmann <kraxel@redhat.com>; aaron.young@oracle.com; Brijesh Singh
> <brijesh.singh@amd.com>
> Subject: [PATCH v2 0/2] SEV BaseMemEncryptLib cleanup
>
> This is the first of cleanup for SEV MemEncryptLib. The library uses
> the CPUID followed by the MSR read to determine whether SEV is enabled.
>
> Now that we have a workarea concept, the logic can be simplified to
> store the msr status in workarea and use that to build PCDs and then
> later simply use the PCDs instead of going through the CPUID and RDMSR.
>
> The complete branch is available at
> https://github.com/codomania/edk2/tree/sev-workarea-cleanup
>
> The series also fixes one of the issue raised in the bug
> https://bugzilla.tianocore.org/show_bug.cgi?id=3582
>
> Changes since v1:
> * Cache the PCD reads so that we can avoid reading PCD while performing the
> virtual pointer conversion.
>
> Brijesh Singh (2):
> OvmfPkg/ResetVector: cache the SEV status MSR value in workarea
> OvmfPkg/BaseMemEncryptLib: use the SEV_STATUS MSR value from workarea
>
> .../DxeMemEncryptSevLib.inf | 1 +
> .../PeiMemEncryptSevLib.inf | 1 +
> .../SecMemEncryptSevLib.inf | 1 +
> OvmfPkg/Include/WorkArea.h | 12 +-
> .../DxeMemEncryptSevLibInternal.c | 145 ++++++++----------
> .../PeiMemEncryptSevLibInternal.c | 139 ++++++-----------
> .../SecMemEncryptSevLibInternal.c | 80 +++++-----
> OvmfPkg/Sec/AmdSev.c | 2 +-
> OvmfPkg/ResetVector/Ia32/AmdSev.asm | 38 +++--
> OvmfPkg/ResetVector/Ia32/Flat32ToFlat64.asm | 3 +-
> OvmfPkg/ResetVector/ResetVector.nasmb | 3 +
> 11 files changed, 194 insertions(+), 231 deletions(-)
>
> --
> 2.25.1
^ permalink raw reply [flat|nested] 5+ messages in thread