From 449a6e493418c337752b68e4f199bd2d7d39af9f Mon Sep 17 00:00:00 2001 From: Tom Lendacky Date: Wed, 12 Aug 2020 15:21:40 -0500 Subject: [PATCH] OvmfPkg: Create GHCB pages for use during Pei and Dxe phase BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198 Allocate memory for the GHCB pages and the per-CPU variable pages during SEV initialization for use during Pei and Dxe phases. The GHCB page(s) must be shared pages, so clear the encryption mask from the current page table entries. Upon successful allocation, set the GHCB PCDs (PcdGhcbBase and PcdGhcbSize). The per-CPU variable page needs to be unique per AP. Using the page after the GHCB ensures that it is unique per AP. Only the GHCB page is marked as shared, keeping the per-CPU variable page encyrpted. The same logic is used in DXE using CreateIdentityMappingPageTables() before switching to the DXE pagetables. The GHCB pages (one per vCPU) will be used by the PEI and DXE #VC exception handlers. The #VC exception handler will fill in the necessary fields of the GHCB and exit to the hypervisor using the VMGEXIT instruction. The hypervisor then accesses the GHCB associated with the vCPU in order to perform the requested function. Cc: Jordan Justen Cc: Laszlo Ersek Cc: Ard Biesheuvel Reviewed-by: Laszlo Ersek Signed-off-by: Tom Lendacky Regression-tested-by: Laszlo Ersek --- OvmfPkg/OvmfPkgIa32.dsc | 2 ++ OvmfPkg/OvmfPkgIa32X64.dsc | 2 ++ OvmfPkg/OvmfPkgX64.dsc | 2 ++ OvmfPkg/PlatformPei/AmdSev.c | 45 ++++++++++++++++++++++++++++- OvmfPkg/PlatformPei/PlatformPei.inf | 2 ++ 5 files changed, 52 insertions(+), 1 deletion(-) diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc index f84f23f250..133a9a93c0 100644 --- a/OvmfPkg/OvmfPkgIa32.dsc +++ b/OvmfPkg/OvmfPkgIa32.dsc @@ -608,6 +608,8 @@ gEfiMdeModulePkgTokenSpaceGuid.PcdPteMemoryEncryptionAddressOrMask|0x0 # Set SEV-ES defaults + gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbBase|0 + gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbSize|0 gUefiCpuPkgTokenSpaceGuid.PcdSevEsIsEnabled|0 !if $(SMM_REQUIRE) == TRUE diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc index a66abccf82..338c38db29 100644 --- a/OvmfPkg/OvmfPkgIa32X64.dsc +++ b/OvmfPkg/OvmfPkgIa32X64.dsc @@ -620,6 +620,8 @@ gEfiMdeModulePkgTokenSpaceGuid.PcdPteMemoryEncryptionAddressOrMask|0x0 # Set SEV-ES defaults + gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbBase|0 + gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbSize|0 gUefiCpuPkgTokenSpaceGuid.PcdSevEsIsEnabled|0 !if $(SMM_REQUIRE) == TRUE diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc index 2a8975fd3d..b80710fbdc 100644 --- a/OvmfPkg/OvmfPkgX64.dsc +++ b/OvmfPkg/OvmfPkgX64.dsc @@ -618,6 +618,8 @@ gEfiMdeModulePkgTokenSpaceGuid.PcdPteMemoryEncryptionAddressOrMask|0x0 # Set SEV-ES defaults + gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbBase|0 + gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbSize|0 gUefiCpuPkgTokenSpaceGuid.PcdSevEsIsEnabled|0 !if $(SMM_REQUIRE) == TRUE diff --git a/OvmfPkg/PlatformPei/AmdSev.c b/OvmfPkg/PlatformPei/AmdSev.c index 4dc5340caa..4fd4534cab 100644 --- a/OvmfPkg/PlatformPei/AmdSev.c +++ b/OvmfPkg/PlatformPei/AmdSev.c @@ -10,12 +10,15 @@ // The package level header files this module uses // #include +#include #include #include #include +#include #include #include #include +#include #include #include @@ -32,7 +35,10 @@ AmdSevEsInitialize ( VOID ) { - RETURN_STATUS PcdStatus; + VOID *GhcbBase; + PHYSICAL_ADDRESS GhcbBasePa; + UINTN GhcbPageCount, PageCount; + RETURN_STATUS PcdStatus, DecryptStatus; if (!MemEncryptSevEsIsEnabled ()) { return; @@ -40,6 +46,43 @@ AmdSevEsInitialize ( PcdStatus = PcdSetBoolS (PcdSevEsIsEnabled, TRUE); ASSERT_RETURN_ERROR (PcdStatus); + + // + // Allocate GHCB and per-CPU variable pages. + // + GhcbPageCount = mMaxCpuCount * 2; + GhcbBase = AllocatePages (GhcbPageCount); + ASSERT (GhcbBase != NULL); + + GhcbBasePa = (PHYSICAL_ADDRESS)(UINTN) GhcbBase; + + // + // Each vCPU gets two consecutive pages, the first is the GHCB and the + // second is the per-CPU variable page. Loop through the allocation and + // only clear the encryption mask for the GHCB pages. + // + for (PageCount = 0; PageCount < GhcbPageCount; PageCount += 2) { + DecryptStatus = MemEncryptSevClearPageEncMask ( + 0, + GhcbBasePa + EFI_PAGES_TO_SIZE (PageCount), + 1, + TRUE + ); + ASSERT_RETURN_ERROR (DecryptStatus); + } + + ZeroMem (GhcbBase, EFI_PAGES_TO_SIZE (GhcbPageCount)); + + PcdStatus = PcdSet64S (PcdGhcbBase, GhcbBasePa); + ASSERT_RETURN_ERROR (PcdStatus); + PcdStatus = PcdSet64S (PcdGhcbSize, EFI_PAGES_TO_SIZE (GhcbPageCount)); + ASSERT_RETURN_ERROR (PcdStatus); + + DEBUG ((DEBUG_INFO, + "SEV-ES is enabled, %lu GHCB pages allocated starting at 0x%p\n", + (UINT64)GhcbPageCount, GhcbBase)); + + AsmWriteMsr64 (MSR_SEV_ES_GHCB, GhcbBasePa); } /** diff --git a/OvmfPkg/PlatformPei/PlatformPei.inf b/OvmfPkg/PlatformPei/PlatformPei.inf index a54d10ba90..4742e1bdf4 100644 --- a/OvmfPkg/PlatformPei/PlatformPei.inf +++ b/OvmfPkg/PlatformPei/PlatformPei.inf @@ -102,6 +102,8 @@ gEfiMdeModulePkgTokenSpaceGuid.PcdSetNxForStack gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiS3Enable gEfiMdeModulePkgTokenSpaceGuid.PcdPteMemoryEncryptionAddressOrMask + gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbBase + gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbSize gEfiSecurityPkgTokenSpaceGuid.PcdOptionRomImageVerificationPolicy gUefiCpuPkgTokenSpaceGuid.PcdCpuLocalApicBaseAddress gUefiCpuPkgTokenSpaceGuid.PcdCpuMaxLogicalProcessorNumber -- 2.39.2