From 3323359a811a597b8ee045638c5addd10444402c Mon Sep 17 00:00:00 2001 From: "Lendacky, Thomas via groups.io" Date: Wed, 29 Mar 2023 02:09:23 +0800 Subject: 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: 06544455d0d4 ("UefiCpuPkg/MpInitLib: Use SEV-SNP AP Creation ...") Signed-off-by: Tom Lendacky Acked-by: Gerd Hoffmann Acked-by: Ray Ni --- UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c | 198 ++++++++++++++++++------------ 1 file changed, 121 insertions(+), 77 deletions(-) (limited to 'UefiCpuPkg') diff --git a/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c b/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c index bfda1e1903..509be9b417 100644 --- a/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c +++ b/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c @@ -13,6 +13,100 @@ #include #include +/** + 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; + + if (CpuData->SevEsSaveArea == NULL) { + // + // Allocate a single page for the SEV-ES Save Area and initialize it. + // + SaveArea = AllocateReservedPages (1); + if (!SaveArea) { + return; + } - // - // 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); } /** -- cgit v1.2.3