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UefiCpuPkg/MpInitLib: Reuse VMSA allocation to avoid unreserved allocation 

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: 06544455d0 ("UefiCpuPkg/MpInitLib: Use SEV-SNP AP Creation ...")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Ray Ni <ray.ni@intel.com>
This commit is contained in:
Lendacky, Thomas via groups.io 2023-03-29 02:09:23 +08:00 committed by mergify[bot]
parent 54051768cd
commit 3323359a81
1 changed files with 121 additions and 77 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

198
UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
View File

@ -13,6 +13,100 @@
#include <Register/Amd/Fam17Msr.h>
#include <Register/Amd/Ghcb.h>
/**
Perform the requested AP Creation action.
@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
**/
STATIC
BOOLEAN
SevSnpPerformApAction (
IN SEV_ES_SAVE_AREA *SaveArea,
IN UINT32 ApicId,
IN UINTN Action
)
{
MSR_SEV_ES_GHCB_REGISTER Msr;
GHCB *Ghcb;
BOOLEAN InterruptState;
UINT64 ExitInfo1;
UINT64 ExitInfo2;
UINT32 RmpAdjustStatus;
UINT64 VmgExitStatus;
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);
}
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.
@ -27,27 +121,33 @@ SevSnpCreateSaveArea (
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;
SEV_ES_SAVE_AREA *SaveArea;
IA32_CR0 ApCr0;
IA32_CR0 ResetCr0;
IA32_CR4 ApCr4;
IA32_CR4 ResetCr4;
UINTN StartIp;
UINT8 SipiVector;
//
// Allocate a single page for the SEV-ES Save Area and initialize it.
//
SaveArea = AllocateReservedPages (1);
if (!SaveArea) {
return;
if (CpuData->SevEsSaveArea == NULL) {
//
// Allocate a single page for the SEV-ES Save Area and initialize it.
//
SaveArea = AllocateReservedPages (1);
if (!SaveArea) {
return;
}
CpuData->SevEsSaveArea = SaveArea;
} else {
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);
@ -132,63 +232,7 @@ 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);
}
/**