[edk2-devel] [RFC PATCH v2 08/44] OvmfPkg: Create GHCB pages for use during Pei and Dxe phase

[Lendacky, Thomas]

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

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198

Allocate memory for the GHCB 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).

Cc: Jordan Justen <jordan.l.jus...@intel.com>
Cc: Laszlo Ersek <ler...@redhat.com>
Cc: Ard Biesheuvel <ard.biesheu...@linaro.org>
Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
---
 OvmfPkg/OvmfPkgIa32.dsc             |  2 ++
 OvmfPkg/OvmfPkgIa32X64.dsc          |  2 ++
 OvmfPkg/OvmfPkgX64.dsc              |  2 ++
 OvmfPkg/PlatformPei/PlatformPei.inf |  2 ++
 OvmfPkg/PlatformPei/AmdSev.c        | 36 ++++++++++++++++++++++++++++-
 5 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc
index 0ce5c01722ef..4369cf6d55e5 100644
--- a/OvmfPkg/OvmfPkgIa32.dsc
+++ b/OvmfPkg/OvmfPkgIa32.dsc
@@ -560,6 +560,8 @@ [PcdsDynamicDefault]
 
   # Set SEV-ES defaults
   gEfiMdeModulePkgTokenSpaceGuid.PcdSevEsActive|0
+  gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbBase|0
+  gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbSize|0
 
 !if $(SMM_REQUIRE) == TRUE
   gUefiOvmfPkgTokenSpaceGuid.PcdQ35TsegMbytes|8
diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
index e7455e35a55d..a74f5028068e 100644
--- a/OvmfPkg/OvmfPkgIa32X64.dsc
+++ b/OvmfPkg/OvmfPkgIa32X64.dsc
@@ -572,6 +572,8 @@ [PcdsDynamicDefault]
 
   # Set SEV-ES defaults
   gEfiMdeModulePkgTokenSpaceGuid.PcdSevEsActive|0
+  gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbBase|0
+  gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbSize|0
 
 !if $(SMM_REQUIRE) == TRUE
   gUefiOvmfPkgTokenSpaceGuid.PcdQ35TsegMbytes|8
diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
index 0b8305cd10a2..fd714d386e75 100644
--- a/OvmfPkg/OvmfPkgX64.dsc
+++ b/OvmfPkg/OvmfPkgX64.dsc
@@ -571,6 +571,8 @@ [PcdsDynamicDefault]
 
   # Set SEV-ES defaults
   gEfiMdeModulePkgTokenSpaceGuid.PcdSevEsActive|0
+  gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbBase|0
+  gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbSize|0
 
 !if $(SMM_REQUIRE) == TRUE
   gUefiOvmfPkgTokenSpaceGuid.PcdQ35TsegMbytes|8
diff --git a/OvmfPkg/PlatformPei/PlatformPei.inf 
b/OvmfPkg/PlatformPei/PlatformPei.inf
index a9e424a6012a..62abc99f4622 100644
--- a/OvmfPkg/PlatformPei/PlatformPei.inf
+++ b/OvmfPkg/PlatformPei/PlatformPei.inf
@@ -105,6 +105,8 @@ [Pcd]
   gUefiCpuPkgTokenSpaceGuid.PcdCpuApInitTimeOutInMicroSeconds
   gUefiCpuPkgTokenSpaceGuid.PcdCpuApStackSize
   gEfiMdeModulePkgTokenSpaceGuid.PcdSevEsActive
+  gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbBase
+  gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbSize
 
 [FixedPcd]
   gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress
diff --git a/OvmfPkg/PlatformPei/AmdSev.c b/OvmfPkg/PlatformPei/AmdSev.c
index 7ae2f26a2ba7..30c0e4af7252 100644
--- a/OvmfPkg/PlatformPei/AmdSev.c
+++ b/OvmfPkg/PlatformPei/AmdSev.c
@@ -16,6 +16,9 @@
 #include <PiPei.h>
 #include <Register/Amd/Cpuid.h>
 #include <Register/Cpuid.h>
+#include <Register/Amd/Msr.h>
+#include <Library/BaseMemoryLib.h>
+#include <Library/MemoryAllocationLib.h>
 
 #include "Platform.h"
 
@@ -30,7 +33,10 @@ AmdSevEsInitialize (
   VOID
   )
 {
-  RETURN_STATUS     PcdStatus;
+  VOID              *GhcbBase;
+  PHYSICAL_ADDRESS  GhcbBasePa;
+  UINTN             GhcbPageCount;
+  RETURN_STATUS     PcdStatus, DecryptStatus;
 
   if (!MemEncryptSevEsIsEnabled ()) {
     return;
@@ -38,6 +44,34 @@ AmdSevEsInitialize (
 
   PcdStatus = PcdSetBoolS (PcdSevEsActive, 1);
   ASSERT_RETURN_ERROR (PcdStatus);
+
+  //
+  // Allocate GHCB pages.
+  //
+  GhcbPageCount = mMaxCpuCount;
+  GhcbBase = AllocatePages (GhcbPageCount);
+  ASSERT (GhcbBase);
+
+  GhcbBasePa = (PHYSICAL_ADDRESS)(UINTN) GhcbBase;
+
+  DecryptStatus = MemEncryptSevClearPageEncMask (
+    0,
+    GhcbBasePa,
+    GhcbPageCount,
+    TRUE
+    );
+  ASSERT_RETURN_ERROR (DecryptStatus);
+
+  SetMem (GhcbBase, GhcbPageCount * SIZE_4KB, 0);
+
+  PcdStatus = PcdSet64S (PcdGhcbBase, (UINT64)GhcbBasePa);
+  ASSERT_RETURN_ERROR (PcdStatus);
+  PcdStatus = PcdSet64S (PcdGhcbSize, (UINT64)EFI_PAGES_TO_SIZE 
(GhcbPageCount));
+  ASSERT_RETURN_ERROR (PcdStatus);
+
+  DEBUG ((DEBUG_INFO, "SEV-ES is enabled, %u GHCB pages allocated starting at 
0x%lx\n", GhcbPageCount, GhcbBase));
+
+  AsmWriteMsr64 (MSR_SEV_ES_GHCB, (UINT64)GhcbBasePa);
 }
 
 /**
-- 
2.17.1


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