[PATCH v9 32/32] UefiCpuPkg/MpInitLib: Use SEV-SNP AP Creation NAE event to launch APs


Gerd Hoffmann
 

On Wed, Oct 13, 2021 at 11:57:13AM -0500, Brijesh Singh wrote:
From: Tom Lendacky <thomas.lendacky@amd.com>

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275

Use the SEV-SNP AP Creation NAE event to create and launch APs under
SEV-SNP. This capability will be advertised in the SEV Hypervisor
Feature Support PCD (PcdSevEsHypervisorFeatures).
Acked-by: Gerd Hoffmann <kraxel@redhat.com>

take care,
Gerd


Brijesh Singh
 

From: Tom Lendacky <thomas.lendacky@amd.com>

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275

Use the SEV-SNP AP Creation NAE event to create and launch APs under
SEV-SNP. This capability will be advertised in the SEV Hypervisor
Feature Support PCD (PcdSevEsHypervisorFeatures).

Cc: Michael Roth <michael.roth@amd.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: James Bottomley <jejb@linux.ibm.com>
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>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf | 3 +
UefiCpuPkg/Library/MpInitLib/PeiMpInitLib.inf | 3 +
UefiCpuPkg/Library/MpInitLib/MpLib.h | 44 +++
UefiCpuPkg/Library/MpInitLib/DxeMpLib.c | 12 +-
UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c | 70 +++++
UefiCpuPkg/Library/MpInitLib/MpLib.c | 51 ++--
UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c | 261 ++++++++++++++++++
7 files changed, 425 insertions(+), 19 deletions(-)
create mode 100644 UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c
create mode 100644 UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c

diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf b/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
index 28764418d7c1..43c104b4da2c 100644
--- a/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
+++ b/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
@@ -22,9 +22,11 @@ [Defines]
#

[Sources.IA32]
+ Ia32/AmdSev.c
Ia32/MpFuncs.nasm

[Sources.X64]
+ X64/AmdSev.c
X64/MpFuncs.nasm

[Sources.common]
@@ -73,6 +75,7 @@ [Pcd]
gUefiCpuPkgTokenSpaceGuid.PcdCpuApLoopMode ## CONSUMES
gUefiCpuPkgTokenSpaceGuid.PcdCpuApTargetCstate ## SOMETIMES_CONSUMES
gUefiCpuPkgTokenSpaceGuid.PcdCpuApStatusCheckIntervalInMicroSeconds ## CONSUMES
+ gUefiCpuPkgTokenSpaceGuid.PcdGhcbHypervisorFeatures ## CONSUMES
gUefiCpuPkgTokenSpaceGuid.PcdSevEsWorkAreaBase ## SOMETIMES_CONSUMES
gEfiMdeModulePkgTokenSpaceGuid.PcdCpuStackGuard ## CONSUMES
gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbBase ## CONSUMES
diff --git a/UefiCpuPkg/Library/MpInitLib/PeiMpInitLib.inf b/UefiCpuPkg/Library/MpInitLib/PeiMpInitLib.inf
index cbc3c1460423..859b9a29fc19 100644
--- a/UefiCpuPkg/Library/MpInitLib/PeiMpInitLib.inf
+++ b/UefiCpuPkg/Library/MpInitLib/PeiMpInitLib.inf
@@ -22,9 +22,11 @@ [Defines]
#

[Sources.IA32]
+ Ia32/AmdSev.c
Ia32/MpFuncs.nasm

[Sources.X64]
+ X64/AmdSev.c
X64/MpFuncs.nasm

[Sources.common]
@@ -64,6 +66,7 @@ [Pcd]
gUefiCpuPkgTokenSpaceGuid.PcdCpuApLoopMode ## CONSUMES
gUefiCpuPkgTokenSpaceGuid.PcdCpuApTargetCstate ## SOMETIMES_CONSUMES
gUefiCpuPkgTokenSpaceGuid.PcdSevEsWorkAreaBase ## SOMETIMES_CONSUMES
+ gUefiCpuPkgTokenSpaceGuid.PcdGhcbHypervisorFeatures ## CONSUMES
gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbBase ## CONSUMES
gUefiCpuPkgTokenSpaceGuid.PcdConfidentialComputingGuestAttr ## CONSUMES

diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.h b/UefiCpuPkg/Library/MpInitLib/MpLib.h
index c52b6157429b..48f6e933bb36 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.h
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.h
@@ -15,6 +15,7 @@

#include <Register/Intel/Cpuid.h>
#include <Register/Amd/Cpuid.h>
+#include <Register/Amd/Ghcb.h>
#include <Register/Intel/Msr.h>
#include <Register/Intel/LocalApic.h>
#include <Register/Intel/Microcode.h>
@@ -150,6 +151,7 @@ typedef struct {
UINT8 PlatformId;
UINT64 MicrocodeEntryAddr;
UINT32 MicrocodeRevision;
+ SEV_ES_SAVE_AREA *SevEsSaveArea;
} CPU_AP_DATA;

//
@@ -294,6 +296,7 @@ struct _CPU_MP_DATA {

BOOLEAN SevEsIsEnabled;
BOOLEAN SevSnpIsEnabled;
+ BOOLEAN UseSevEsAPMethod;
UINTN SevEsAPBuffer;
UINTN SevEsAPResetStackStart;
CPU_MP_DATA *NewCpuMpData;
@@ -790,5 +793,46 @@ ConfidentialComputingGuestHas (
CONFIDENTIAL_COMPUTING_GUEST_ATTR Attr
);

+/**
+ Issue RMPADJUST to adjust the VMSA attribute of an SEV-SNP page.
+
+ @param[in] PageAddress
+ @param[in] VmsaPage
+
+ @return RMPADJUST return value
+**/
+UINT32
+SevSnpRmpAdjust (
+ IN EFI_PHYSICAL_ADDRESS PageAddress,
+ IN BOOLEAN VmsaPage
+ );
+
+/**
+ Create an SEV-SNP AP save area (VMSA) for use in running the vCPU.
+
+ @param[in] CpuMpData Pointer to CPU MP Data
+ @param[in] CpuData Pointer to CPU AP Data
+ @param[in] ApicId APIC ID of the vCPU
+**/
+VOID
+SevSnpCreateSaveArea (
+ IN CPU_MP_DATA *CpuMpData,
+ IN CPU_AP_DATA *CpuData,
+ UINT32 ApicId
+ );
+
+/**
+ Create SEV-SNP APs.
+
+ @param[in] CpuMpData Pointer to CPU MP Data
+ @param[in] ProcessorNumber The handle number of specified processor
+ (-1 for all APs)
+**/
+VOID
+SevSnpCreateAP (
+ IN CPU_MP_DATA *CpuMpData,
+ IN INTN ProcessorNumber
+ );
+
#endif

diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
index 657a73dca05e..7a3ef0015a31 100644
--- a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
@@ -93,7 +93,13 @@ GetWakeupBuffer (
EFI_PHYSICAL_ADDRESS StartAddress;
EFI_MEMORY_TYPE MemoryType;

- if (ConfidentialComputingGuestHas (CCAttrAmdSevEs)) {
+ if (ConfidentialComputingGuestHas (CCAttrAmdSevEs) &&
+ !ConfidentialComputingGuestHas (CCAttrAmdSevSnp)) {
+ //
+ // An SEV-ES-only guest requires the memory to be reserved. SEV-SNP, which
+ // is also considered SEV-ES, uses a different AP startup method, though,
+ // which does not have the same requirement.
+ //
MemoryType = EfiReservedMemoryType;
} else {
MemoryType = EfiBootServicesData;
@@ -373,7 +379,7 @@ RelocateApLoop (
MpInitLibWhoAmI (&ProcessorNumber);
CpuMpData = GetCpuMpData ();
MwaitSupport = IsMwaitSupport ();
- if (CpuMpData->SevEsIsEnabled) {
+ if (CpuMpData->UseSevEsAPMethod) {
StackStart = CpuMpData->SevEsAPResetStackStart;
} else {
StackStart = mReservedTopOfApStack;
@@ -422,7 +428,7 @@ MpInitChangeApLoopCallback (
CpuPause ();
}

- if (CpuMpData->SevEsIsEnabled && (CpuMpData->WakeupBuffer != (UINTN) -1)) {
+ if (CpuMpData->UseSevEsAPMethod && (CpuMpData->WakeupBuffer != (UINTN) -1)) {
//
// There are APs present. Re-use reserved memory area below 1MB from
// WakeupBuffer as the area to be used for transitioning to 16-bit mode
diff --git a/UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c b/UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c
new file mode 100644
index 000000000000..a4702e298d98
--- /dev/null
+++ b/UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c
@@ -0,0 +1,70 @@
+/** @file
+
+ AMD SEV helper function.
+
+ Copyright (c) 2021, AMD Incorporated. All rights reserved.<BR>
+
+ SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include "MpLib.h"
+
+/**
+ Create an SEV-SNP AP save area (VMSA) for use in running the vCPU.
+
+ @param[in] CpuMpData Pointer to CPU MP Data
+ @param[in] CpuData Pointer to CPU AP Data
+ @param[in] ApicId APIC ID of the vCPU
+**/
+VOID
+SevSnpCreateSaveArea (
+ IN CPU_MP_DATA *CpuMpData,
+ IN CPU_AP_DATA *CpuData,
+ UINT32 ApicId
+ )
+{
+ //
+ // SEV-SNP is not support on 32-bit build.
+ //
+ ASSERT (FALSE);
+}
+
+/**
+ Create SEV-SNP APs.
+
+ @param[in] CpuMpData Pointer to CPU MP Data
+ @param[in] ProcessorNumber The handle number of specified processor
+ (-1 for all APs)
+**/
+VOID
+SevSnpCreateAP (
+ IN CPU_MP_DATA *CpuMpData,
+ IN INTN ProcessorNumber
+ )
+{
+ //
+ // SEV-SNP is not support on 32-bit build.
+ //
+ ASSERT (FALSE);
+}
+
+/**
+ Issue RMPADJUST to adjust the VMSA attribute of an SEV-SNP page.
+
+ @param[in] PageAddress
+ @param[in] VmsaPage
+
+ @return RMPADJUST return value
+**/
+UINT32
+SevSnpRmpAdjust (
+ IN EFI_PHYSICAL_ADDRESS PageAddress,
+ IN BOOLEAN VmsaPage
+ )
+{
+ //
+ // RMPADJUST is not supported in 32-bit mode
+ //
+ return RETURN_UNSUPPORTED;
+}
diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index de94b05e2263..758412058fe6 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -295,10 +295,11 @@ GetApLoopMode (
ApLoopMode = ApInHltLoop;
}

- if (ConfidentialComputingGuestHas (CCAttrAmdSevEs)) {
+ if (ConfidentialComputingGuestHas (CCAttrAmdSevEs) &&
+ !ConfidentialComputingGuestHas (CCAttrAmdSevSnp)) {
//
- // For SEV-ES, force AP in Hlt-loop mode in order to use the GHCB
- // protocol for starting APs
+ // For SEV-ES (SEV-SNP is also considered SEV-ES), force AP in Hlt-loop
+ // mode in order to use the GHCB protocol for starting APs
//
ApLoopMode = ApInHltLoop;
}
@@ -758,7 +759,7 @@ ApWakeupFunction (
// to allow the APs to issue an AP_RESET_HOLD before the BSP possibly
// performs another INIT-SIPI-SIPI sequence.
//
- if (!CpuMpData->SevEsIsEnabled) {
+ if (!CpuMpData->UseSevEsAPMethod) {
InterlockedDecrement ((UINT32 *) &CpuMpData->MpCpuExchangeInfo->NumApsExecuting);
}
}
@@ -772,7 +773,7 @@ ApWakeupFunction (
//
while (TRUE) {
DisableInterrupts ();
- if (CpuMpData->SevEsIsEnabled) {
+ if (CpuMpData->UseSevEsAPMethod) {
SevEsPlaceApHlt (CpuMpData);
} else {
CpuSleep ();
@@ -1056,9 +1057,12 @@ AllocateResetVector (
);
//
// The AP reset stack is only used by SEV-ES guests. Do not allocate it
- // if SEV-ES is not enabled.
+ // if SEV-ES is not enabled. An SEV-SNP guest is also considered
+ // an SEV-ES guest, but uses a different method of AP startup, eliminating
+ // the need for the allocation.
//
- if (ConfidentialComputingGuestHas (CCAttrAmdSevEs)) {
+ if (ConfidentialComputingGuestHas (CCAttrAmdSevEs) &&
+ !ConfidentialComputingGuestHas (CCAttrAmdSevSnp)) {
//
// Stack location is based on ProcessorNumber, so use the total number
// of processors for calculating the total stack area.
@@ -1108,7 +1112,7 @@ FreeResetVector (
// perform the restore as this will overwrite memory which has data
// needed by SEV-ES.
//
- if (!CpuMpData->SevEsIsEnabled) {
+ if (!CpuMpData->UseSevEsAPMethod) {
RestoreWakeupBuffer (CpuMpData);
}
}
@@ -1144,7 +1148,7 @@ WakeUpAP (
ResetVectorRequired = FALSE;

if (CpuMpData->WakeUpByInitSipiSipi ||
- CpuMpData->InitFlag != ApInitDone) {
+ CpuMpData->InitFlag != ApInitDone) {
ResetVectorRequired = TRUE;
AllocateResetVector (CpuMpData);
AllocateSevEsAPMemory (CpuMpData);
@@ -1185,7 +1189,7 @@ WakeUpAP (
}
if (ResetVectorRequired) {
//
- // For SEV-ES, the initial AP boot address will be defined by
+ // For SEV-ES and SEV-SNP, the initial AP boot address will be defined by
// PcdSevEsWorkAreaBase. The Segment/Rip must be the jump address
// from the original INIT-SIPI-SIPI.
//
@@ -1195,8 +1199,14 @@ WakeUpAP (

//
// Wakeup all APs
+ // Must use the INIT-SIPI-SIPI method for initial configuration in
+ // order to obtain the APIC ID.
//
- SendInitSipiSipiAllExcludingSelf ((UINT32) ExchangeInfo->BufferStart);
+ if (CpuMpData->SevSnpIsEnabled && CpuMpData->InitFlag != ApInitConfig) {
+ SevSnpCreateAP (CpuMpData, -1);
+ } else {
+ SendInitSipiSipiAllExcludingSelf ((UINT32) ExchangeInfo->BufferStart);
+ }
}
if (CpuMpData->InitFlag == ApInitConfig) {
if (PcdGet32 (PcdCpuBootLogicalProcessorNumber) > 0) {
@@ -1286,7 +1296,7 @@ WakeUpAP (
CpuInfoInHob = (CPU_INFO_IN_HOB *) (UINTN) CpuMpData->CpuInfoInHob;

//
- // For SEV-ES, the initial AP boot address will be defined by
+ // For SEV-ES and SEV-SNP, the initial AP boot address will be defined by
// PcdSevEsWorkAreaBase. The Segment/Rip must be the jump address
// from the original INIT-SIPI-SIPI.
//
@@ -1294,10 +1304,14 @@ WakeUpAP (
SetSevEsJumpTable (ExchangeInfo->BufferStart);
}

- SendInitSipiSipi (
- CpuInfoInHob[ProcessorNumber].ApicId,
- (UINT32) ExchangeInfo->BufferStart
- );
+ if (CpuMpData->SevSnpIsEnabled && CpuMpData->InitFlag != ApInitConfig) {
+ SevSnpCreateAP (CpuMpData, (INTN) ProcessorNumber);
+ } else {
+ SendInitSipiSipi (
+ CpuInfoInHob[ProcessorNumber].ApicId,
+ (UINT32) ExchangeInfo->BufferStart
+ );
+ }
}
//
// Wait specified AP waken up
@@ -1832,6 +1846,11 @@ MpInitLibInitialize (
CpuMpData->SevSnpIsEnabled = ConfidentialComputingGuestHas (CCAttrAmdSevSnp);
CpuMpData->SevEsAPBuffer = (UINTN) -1;
CpuMpData->GhcbBase = PcdGet64 (PcdGhcbBase);
+ CpuMpData->UseSevEsAPMethod = CpuMpData->SevEsIsEnabled && !CpuMpData->SevSnpIsEnabled;
+
+ if (CpuMpData->SevSnpIsEnabled) {
+ ASSERT ((PcdGet64 (PcdGhcbHypervisorFeatures) & GHCB_HV_FEATURES_SNP_AP_CREATE) == GHCB_HV_FEATURES_SNP_AP_CREATE);
+ }

//
// Make sure no memory usage outside of the allocated buffer.
diff --git a/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c b/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
new file mode 100644
index 000000000000..303271abdaad
--- /dev/null
+++ b/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
@@ -0,0 +1,261 @@
+/** @file
+
+ AMD SEV helper function.
+
+ Copyright (c) 2021, AMD Incorporated. All rights reserved.<BR>
+
+ SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include "MpLib.h"
+#include <Library/VmgExitLib.h>
+#include <Register/Amd/Fam17Msr.h>
+#include <Register/Amd/Ghcb.h>
+
+/**
+ Create an SEV-SNP AP save area (VMSA) for use in running the vCPU.
+
+ @param[in] CpuMpData Pointer to CPU MP Data
+ @param[in] CpuData Pointer to CPU AP Data
+ @param[in] ApicId APIC ID of the vCPU
+**/
+VOID
+SevSnpCreateSaveArea (
+ IN CPU_MP_DATA *CpuMpData,
+ IN CPU_AP_DATA *CpuData,
+ UINT32 ApicId
+ )
+{
+ SEV_ES_SAVE_AREA *SaveArea;
+ IA32_CR0 ApCr0;
+ IA32_CR0 ResetCr0;
+ IA32_CR4 ApCr4;
+ IA32_CR4 ResetCr4;
+ UINTN StartIp;
+ UINT8 SipiVector;
+ UINT32 RmpAdjustStatus;
+ UINT64 VmgExitStatus;
+ MSR_SEV_ES_GHCB_REGISTER Msr;
+ GHCB *Ghcb;
+ BOOLEAN InterruptState;
+ UINT64 ExitInfo1;
+ UINT64 ExitInfo2;
+
+ //
+ // Allocate a single page for the SEV-ES Save Area and initialize it.
+ //
+ SaveArea = AllocateReservedPages (1);
+ if (!SaveArea) {
+ return;
+ }
+ ZeroMem (SaveArea, EFI_PAGE_SIZE);
+
+ //
+ // Propogate the CR0.NW and CR0.CD setting to the AP
+ //
+ ResetCr0.UintN = 0x00000010;
+ ApCr0.UintN = CpuData->VolatileRegisters.Cr0;
+ if (ApCr0.Bits.NW) {
+ ResetCr0.Bits.NW = 1;
+ }
+ if (ApCr0.Bits.CD) {
+ ResetCr0.Bits.CD = 1;
+ }
+
+ //
+ // Propagate the CR4.MCE setting to the AP
+ //
+ ResetCr4.UintN = 0;
+ ApCr4.UintN = CpuData->VolatileRegisters.Cr4;
+ if (ApCr4.Bits.MCE) {
+ ResetCr4.Bits.MCE = 1;
+ }
+
+ //
+ // Convert the start IP into a SIPI Vector
+ //
+ StartIp = CpuMpData->MpCpuExchangeInfo->BufferStart;
+ SipiVector = (UINT8) (StartIp >> 12);
+
+ //
+ // Set the CS:RIP value based on the start IP
+ //
+ SaveArea->Cs.Base = SipiVector << 12;
+ SaveArea->Cs.Selector = SipiVector << 8;
+ SaveArea->Cs.Limit = 0xFFFF;
+ SaveArea->Cs.Attributes.Bits.Present = 1;
+ SaveArea->Cs.Attributes.Bits.Sbit = 1;
+ SaveArea->Cs.Attributes.Bits.Type = SEV_ES_RESET_CODE_SEGMENT_TYPE;
+ SaveArea->Rip = StartIp & 0xFFF;
+
+ //
+ // Set the remaining values as defined in APM for INIT
+ //
+ SaveArea->Ds.Limit = 0xFFFF;
+ SaveArea->Ds.Attributes.Bits.Present = 1;
+ SaveArea->Ds.Attributes.Bits.Sbit = 1;
+ SaveArea->Ds.Attributes.Bits.Type = SEV_ES_RESET_DATA_SEGMENT_TYPE;
+ SaveArea->Es = SaveArea->Ds;
+ SaveArea->Fs = SaveArea->Ds;
+ SaveArea->Gs = SaveArea->Ds;
+ SaveArea->Ss = SaveArea->Ds;
+
+ SaveArea->Gdtr.Limit = 0xFFFF;
+ SaveArea->Ldtr.Limit = 0xFFFF;
+ SaveArea->Ldtr.Attributes.Bits.Present = 1;
+ SaveArea->Ldtr.Attributes.Bits.Type = SEV_ES_RESET_LDT_TYPE;
+ SaveArea->Idtr.Limit = 0xFFFF;
+ SaveArea->Tr.Limit = 0xFFFF;
+ SaveArea->Ldtr.Attributes.Bits.Present = 1;
+ SaveArea->Ldtr.Attributes.Bits.Type = SEV_ES_RESET_TSS_TYPE;
+
+ SaveArea->Efer = 0x1000;
+ SaveArea->Cr4 = ResetCr4.UintN;
+ SaveArea->Cr0 = ResetCr0.UintN;
+ SaveArea->Dr7 = 0x0400;
+ SaveArea->Dr6 = 0xFFFF0FF0;
+ SaveArea->Rflags = 0x0002;
+ SaveArea->GPat = 0x0007040600070406ULL;
+ SaveArea->XCr0 = 0x0001;
+ SaveArea->Mxcsr = 0x1F80;
+ SaveArea->X87Ftw = 0x5555;
+ SaveArea->X87Fcw = 0x0040;
+
+ //
+ // Set the SEV-SNP specific fields for the save area:
+ // VMPL - always VMPL0
+ // SEV_FEATURES - equivalent to the SEV_STATUS MSR right shifted 2 bits
+ //
+ SaveArea->Vmpl = 0;
+ SaveArea->SevFeatures = AsmReadMsr64 (MSR_SEV_STATUS) >> 2;
+
+ //
+ // To turn the page into a recognized VMSA page, issue RMPADJUST:
+ // Target VMPL but numerically higher than current VMPL
+ // Target PermissionMask is not used
+ //
+ RmpAdjustStatus = SevSnpRmpAdjust (
+ (EFI_PHYSICAL_ADDRESS) (UINTN) SaveArea,
+ TRUE
+ );
+ ASSERT (RmpAdjustStatus == 0);
+
+ ExitInfo1 = (UINT64) ApicId << 32;
+ ExitInfo1 |= SVM_VMGEXIT_SNP_AP_CREATE;
+ ExitInfo2 = (UINT64) (UINTN) SaveArea;
+
+ Msr.GhcbPhysicalAddress = AsmReadMsr64 (MSR_SEV_ES_GHCB);
+ Ghcb = Msr.Ghcb;
+
+ VmgInit (Ghcb, &InterruptState);
+ Ghcb->SaveArea.Rax = SaveArea->SevFeatures;
+ VmgSetOffsetValid (Ghcb, GhcbRax);
+ VmgExitStatus = VmgExit (
+ Ghcb,
+ SVM_EXIT_SNP_AP_CREATION,
+ ExitInfo1,
+ ExitInfo2
+ );
+ VmgDone (Ghcb, InterruptState);
+
+ ASSERT (VmgExitStatus == 0);
+ if (VmgExitStatus != 0) {
+ RmpAdjustStatus = SevSnpRmpAdjust (
+ (EFI_PHYSICAL_ADDRESS) (UINTN) SaveArea,
+ FALSE
+ );
+ if (RmpAdjustStatus == 0) {
+ FreePages (SaveArea, 1);
+ } else {
+ DEBUG ((DEBUG_INFO, "SEV-SNP: RMPADJUST failed, leaking VMSA page\n"));
+ }
+
+ SaveArea = NULL;
+ }
+
+ if (CpuData->SevEsSaveArea) {
+ RmpAdjustStatus = SevSnpRmpAdjust (
+ (EFI_PHYSICAL_ADDRESS) (UINTN) CpuData->SevEsSaveArea,
+ FALSE
+ );
+ if (RmpAdjustStatus == 0) {
+ FreePages (CpuData->SevEsSaveArea, 1);
+ } else {
+ DEBUG ((DEBUG_INFO, "SEV-SNP: RMPADJUST failed, leaking VMSA page\n"));
+ }
+ }
+
+ CpuData->SevEsSaveArea = SaveArea;
+}
+
+/**
+ Create SEV-SNP APs.
+
+ @param[in] CpuMpData Pointer to CPU MP Data
+ @param[in] ProcessorNumber The handle number of specified processor
+ (-1 for all APs)
+**/
+VOID
+SevSnpCreateAP (
+ IN CPU_MP_DATA *CpuMpData,
+ IN INTN ProcessorNumber
+ )
+{
+ CPU_INFO_IN_HOB *CpuInfoInHob;
+ CPU_AP_DATA *CpuData;
+ UINTN Index;
+ UINT32 ApicId;
+
+ ASSERT (CpuMpData->MpCpuExchangeInfo->BufferStart < 0x100000);
+
+ CpuInfoInHob = (CPU_INFO_IN_HOB *) (UINTN) CpuMpData->CpuInfoInHob;
+
+ if (ProcessorNumber < 0) {
+ for (Index = 0; Index < CpuMpData->CpuCount; Index++) {
+ if (Index != CpuMpData->BspNumber) {
+ CpuData = &CpuMpData->CpuData[Index];
+ ApicId = CpuInfoInHob[Index].ApicId,
+ SevSnpCreateSaveArea (CpuMpData, CpuData, ApicId);
+ }
+ }
+ } else {
+ Index = (UINTN) ProcessorNumber;
+ CpuData = &CpuMpData->CpuData[Index];
+ ApicId = CpuInfoInHob[ProcessorNumber].ApicId,
+ SevSnpCreateSaveArea (CpuMpData, CpuData, ApicId);
+ }
+}
+
+/**
+ Issue RMPADJUST to adjust the VMSA attribute of an SEV-SNP page.
+
+ @param[in] PageAddress
+ @param[in] VmsaPage
+
+ @return RMPADJUST return value
+**/
+UINT32
+SevSnpRmpAdjust (
+ IN EFI_PHYSICAL_ADDRESS PageAddress,
+ IN BOOLEAN VmsaPage
+ )
+{
+ UINT64 Rdx;
+
+ //
+ // The RMPADJUST instruction is used to set or clear the VMSA bit for a
+ // page. The VMSA change is only made when running at VMPL0 and is ignored
+ // otherwise. If too low a target VMPL is specified, the instruction can
+ // succeed without changing the VMSA bit when not running at VMPL0. Using a
+ // target VMPL level of 1, RMPADJUST will return a FAIL_PERMISSION error if
+ // not running at VMPL0, thus ensuring that the VMSA bit is set appropriately
+ // when no error is returned.
+ //
+ Rdx = 1;
+ if (VmsaPage) {
+ Rdx |= RMPADJUST_VMSA_PAGE_BIT;
+ }
+
+ return AsmRmpAdjust ((UINT64) PageAddress, 0, Rdx);
+}
--
2.25.1