[PATCH v8 5/6] OvmfPkg/PlatformPei: Mark SEC GHCB page as unencrypted via hypercall

["Ashish Kalra" <ashish.kalra@amd.com>]

From: Ashish Kalra <ashish.kalra@amd.com>

Mark the SEC GHCB page (that is mapped as unencrypted in
ResetVector code) in the hypervisor's guest page encryption
state tracking.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
 OvmfPkg/PlatformPei/AmdSev.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/OvmfPkg/PlatformPei/AmdSev.c b/OvmfPkg/PlatformPei/AmdSev.c
index 385562b44c..cd96fc23bd 100644
--- a/OvmfPkg/PlatformPei/AmdSev.c
+++ b/OvmfPkg/PlatformPei/AmdSev.c
@@ -223,6 +223,17 @@ AmdSevEsInitialize (
   PcdStatus = PcdSetBoolS (PcdSevEsIsEnabled, TRUE);
   ASSERT_RETURN_ERROR (PcdStatus);
 
+  //
+  // The SEC Ghcb setup during reset-vector needs to be marked as
+  // decrypted in the hypervisor's guest page encryption state
+  // tracking.
+  //
+  SetMemoryEncDecHypercall3 (
+    FixedPcdGet32 (PcdOvmfSecGhcbBase),
+    EFI_SIZE_TO_PAGES (FixedPcdGet32 (PcdOvmfSecGhcbSize)),
+    FALSE
+    );
+
   //
   // Allocate GHCB and per-CPU variable pages.
   //   Since the pages must survive across the UEFI to OS transition
-- 
2.25.1