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

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

An SEV-ES guest will generate a #VC exception when it encounters a
non-automatic exit (NAE) event. It is expected that the #VC exception
handler will communicate with the hypervisor using the GHCB to handle
the NAE event.

NAE events can occur during the Sec phase, so initialize exception
handling early in the OVMF Sec support. Add to the basic #VC exception
handler to set the GHCB MSR to a pre-allocated GHCB and call a common
#VC handler.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 OvmfPkg/Sec/SecMain.inf |  1 +
 OvmfPkg/Sec/SecMain.c   | 29 ++++++++++++++++-------------
 2 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/OvmfPkg/Sec/SecMain.inf b/OvmfPkg/Sec/SecMain.inf
index 63ba4cb555fb..7f53845f5436 100644
--- a/OvmfPkg/Sec/SecMain.inf
+++ b/OvmfPkg/Sec/SecMain.inf
@@ -50,6 +50,7 @@ [LibraryClasses]
   PeCoffExtraActionLib
   ExtractGuidedSectionLib
   LocalApicLib
+  CpuExceptionHandlerLib
 
 [Ppis]
   gEfiTemporaryRamSupportPpiGuid                # PPI ALWAYS_PRODUCED
diff --git a/OvmfPkg/Sec/SecMain.c b/OvmfPkg/Sec/SecMain.c
index 3914355cd17b..7f1dfb2e57c1 100644
--- a/OvmfPkg/Sec/SecMain.c
+++ b/OvmfPkg/Sec/SecMain.c
@@ -24,6 +24,7 @@
 #include <Library/PeCoffExtraActionLib.h>
 #include <Library/ExtractGuidedSectionLib.h>
 #include <Library/LocalApicLib.h>
+#include <Library/CpuExceptionHandlerLib.h>
 
 #include <Ppi/TemporaryRamSupport.h>
 
@@ -737,6 +738,21 @@ SecCoreStartupWithStack (
     Table[Index] = 0;
   }
 
+  //
+  // Initialize IDT
+  //
+  IdtTableInStack.PeiService = NULL;
+  for (Index = 0; Index < SEC_IDT_ENTRY_COUNT; Index ++) {
+    CopyMem (&IdtTableInStack.IdtTable[Index], &mIdtEntryTemplate, sizeof (mIdtEntryTemplate));
+  }
+
+  IdtDescriptor.Base  = (UINTN)&IdtTableInStack.IdtTable;
+  IdtDescriptor.Limit = (UINT16)(sizeof (IdtTableInStack.IdtTable) - 1);
+
+  AsmWriteIdtr (&IdtDescriptor);
+
+  InitializeCpuExceptionHandlers (NULL);
+
   ProcessLibraryConstructorList (NULL, NULL);
 
   DEBUG ((EFI_D_INFO,
@@ -751,19 +767,6 @@ SecCoreStartupWithStack (
   //
   InitializeFloatingPointUnits ();
 
-  //
-  // Initialize IDT
-  //  
-  IdtTableInStack.PeiService = NULL;
-  for (Index = 0; Index < SEC_IDT_ENTRY_COUNT; Index ++) {
-    CopyMem (&IdtTableInStack.IdtTable[Index], &mIdtEntryTemplate, sizeof (mIdtEntryTemplate));
-  }
-
-  IdtDescriptor.Base  = (UINTN)&IdtTableInStack.IdtTable;
-  IdtDescriptor.Limit = (UINT16)(sizeof (IdtTableInStack.IdtTable) - 1);
-
-  AsmWriteIdtr (&IdtDescriptor);
-
 #if defined (MDE_CPU_X64)
   //
   // ASSERT that the Page Tables were set by the reset vector code to
-- 
2.17.1


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