https://bugzilla.tianocore.org/show_bug.cgi?id=4353
When parking the APs on exiting from UEFI, a new page allocation is made.
This allocation, however, does not end up being marked reserved in the
memory map supplied to the OS. To avoid this, re-use the VMSA by clearing
the VMSA RMP flag, updating the page contents and re-setting the VMSA RMP
flag.
Fixes: 06544455d0d4 ("UefiCpuPkg/MpInitLib: Use SEV-SNP AP Creation ...")
Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
---
UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c | 234 +++++++++++++---------
1 file changed, 139 insertions(+), 95 deletions(-)
diff --git a/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
b/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
index 7abdda3e1c7e..ae88bbbfd828 100644
--- a/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
+++ b/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
@@ -16,58 +16,158 @@
#define IS_ALIGNED(x, y) ((((UINTN)(x) & (y - 1)) == 0))
/**
- Create an SEV-SNP AP save area (VMSA) for use in running the vCPU.
+ Perform the requested AP Creation action.
- @param[in] CpuMpData Pointer to CPU MP Data
- @param[in] CpuData Pointer to CPU AP Data
+ @param[in] SaveArea Pointer to VM save area (VMSA)
@param[in] ApicId APIC ID of the vCPU
+ @param[in] Action AP action to perform
+
+ @retval TRUE Action completed successfully
+ @retval FALSE Action did not complete successfully
**/
-VOID
-SevSnpCreateSaveArea (
- IN CPU_MP_DATA *CpuMpData,
- IN CPU_AP_DATA *CpuData,
- UINT32 ApicId
+STATIC
+BOOLEAN
+SevSnpPerformApAction (
+ IN SEV_ES_SAVE_AREA *SaveArea,
+ IN UINT32 ApicId,
+ IN UINTN Action
)
{
- UINT8 *Pages;
- 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;
+ UINT64 VmgExitStatus;
+ UINT32 RmpAdjustStatus;
- //
- // Allocate a single page for the SEV-ES Save Area and initialize it.
- // Due to an erratum that prevents a VMSA being on a 2MB boundary,
- // allocate an extra page to work around the issue.
- //
- Pages = AllocateReservedPages (2);
- if (!Pages) {
- return;
+ if (Action == SVM_VMGEXIT_SNP_AP_CREATE) {
+ //
+ // 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
+ );
+ if (RmpAdjustStatus != 0) {
+ DEBUG ((DEBUG_INFO, "SEV-SNP: RMPADJUST failed for VMSA creation\n"));
+ ASSERT (FALSE);
+
+ return FALSE;
+ }
+ }
+
+ ExitInfo1 = (UINT64)ApicId << 32;
+ ExitInfo1 |= Action;
+ ExitInfo2 = (UINT64)(UINTN)SaveArea;
+
+ Msr.GhcbPhysicalAddress = AsmReadMsr64 (MSR_SEV_ES_GHCB);
+ Ghcb = Msr.Ghcb;
+
+ CcExitVmgInit (Ghcb, &InterruptState);
+
+ if (Action == SVM_VMGEXIT_SNP_AP_CREATE) {
+ Ghcb->SaveArea.Rax = SaveArea->SevFeatures;
+ CcExitVmgSetOffsetValid (Ghcb, GhcbRax);
}
- //
- // Since page allocation works by allocating downward in the address space,
- // try to always free the first (lower address) page to limit possible holes
- // in the memory map. So, if the address of the second page is 2MB aligned,
- // then use the first page and free the second page. Otherwise, free the
- // first page and use the second page.
- //
- if (IS_ALIGNED (Pages + EFI_PAGE_SIZE, SIZE_2MB)) {
- SaveArea = (SEV_ES_SAVE_AREA *)Pages;
- FreePages (Pages + EFI_PAGE_SIZE, 1);
+ VmgExitStatus = CcExitVmgExit (
+ Ghcb,
+ SVM_EXIT_SNP_AP_CREATION,
+ ExitInfo1,
+ ExitInfo2
+ );
+
+ CcExitVmgDone (Ghcb, InterruptState);
+
+ if (VmgExitStatus != 0) {
+ DEBUG ((DEBUG_INFO, "SEV-SNP: AP Destroy failed\n"));
+ ASSERT (FALSE);
+
+ return FALSE;
+ }
+
+ if (Action == SVM_VMGEXIT_SNP_AP_DESTROY) {
+ //
+ // Make the current VMSA not runnable and accessible to be
+ // reprogrammed.
+ //
+ RmpAdjustStatus = SevSnpRmpAdjust (
+ (EFI_PHYSICAL_ADDRESS)(UINTN)SaveArea,
+ FALSE
+ );
+ if (RmpAdjustStatus != 0) {
+ DEBUG ((DEBUG_INFO, "SEV-SNP: RMPADJUST failed for VMSA reset\n"));
+ ASSERT (FALSE);
+
+ return FALSE;
+ }
+ }
+
+ return TRUE;
+}
+
+/**
+ 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
+ )
+{
+ UINT8 *Pages;
+ SEV_ES_SAVE_AREA *SaveArea;
+ IA32_CR0 ApCr0;
+ IA32_CR0 ResetCr0;
+ IA32_CR4 ApCr4;
+ IA32_CR4 ResetCr4;
+ UINTN StartIp;
+ UINT8 SipiVector;
+
+ if (CpuData->SevEsSaveArea == NULL) {
+ //
+ // Allocate a single page for the SEV-ES Save Area and initialize it.
+ // Due to an erratum that prevents a VMSA being on a 2MB boundary,
+ // allocate an extra page to work around the issue.
+ //
+ Pages = AllocateReservedPages (2);
+ if (!Pages) {
+ return;
+ }
+
+ //
+ // Since page allocation works by allocating downward in the address space,
+ // try to always free the first (lower address) page to limit possible
holes
+ // in the memory map. So, if the address of the second page is 2MB aligned,
+ // then use the first page and free the second page. Otherwise, free the
+ // first page and use the second page.
+ //
+ if (IS_ALIGNED (Pages + EFI_PAGE_SIZE, SIZE_2MB)) {
+ SaveArea = (SEV_ES_SAVE_AREA *)Pages;
+ FreePages (Pages + EFI_PAGE_SIZE, 1);
+ } else {
+ SaveArea = (SEV_ES_SAVE_AREA *)(Pages + EFI_PAGE_SIZE);
+ FreePages (Pages, 1);
+ }
+
+ CpuData->SevEsSaveArea = SaveArea;
} else {
- SaveArea = (SEV_ES_SAVE_AREA *)(Pages + EFI_PAGE_SIZE);
- FreePages (Pages, 1);
+ SaveArea = CpuData->SevEsSaveArea;
+
+ //
+ // Tell the hypervisor to not use the current VMSA
+ //
+ if (!SevSnpPerformApAction (SaveArea, ApicId, SVM_VMGEXIT_SNP_AP_DESTROY))
{
+ return;
+ }
}
ZeroMem (SaveArea, EFI_PAGE_SIZE);
@@ -152,63 +252,7 @@ SevSnpCreateSaveArea (
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;
-
- CcExitVmgInit (Ghcb, &InterruptState);
- Ghcb->SaveArea.Rax = SaveArea->SevFeatures;
- CcExitVmgSetOffsetValid (Ghcb, GhcbRax);
- VmgExitStatus = CcExitVmgExit (
- Ghcb,
- SVM_EXIT_SNP_AP_CREATION,
- ExitInfo1,
- ExitInfo2
- );
- CcExitVmgDone (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;
+ SevSnpPerformApAction (SaveArea, ApicId, SVM_VMGEXIT_SNP_AP_CREATE);
}
/**
--
2.39.1
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