From 2fe8edfe55ea28d9972ce3ba049783f0616007fa Mon Sep 17 00:00:00 2001
From: "Brijesh Singh via groups.io" <brijesh.singh=amd.com@groups.io>
Date: Thu, 9 Dec 2021 11:27:31 +0800
Subject: OvmfPkg/ResetVector: move clearing GHCB in SecMain

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275

In preparation for SEV-SNP support move clearing of the GHCB memory from
the ResetVector/AmdSev.asm to SecMain/AmdSev.c. The GHCB page is not
accessed until SevEsProtocolCheck() switch to full GHCB. So, the move
does not make any changes in the code flow or logic. The move will
simplify the SEV-SNP support.

Cc: Michael Roth <michael.roth@amd.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
 OvmfPkg/ResetVector/Ia32/AmdSev.asm | 6 ------
 OvmfPkg/Sec/AmdSev.c                | 2 +-
 2 files changed, 1 insertion(+), 7 deletions(-)

diff --git a/OvmfPkg/ResetVector/Ia32/AmdSev.asm b/OvmfPkg/ResetVector/Ia32/AmdSev.asm
index 250ac8d8b1..48d9178168 100644
--- a/OvmfPkg/ResetVector/Ia32/AmdSev.asm
+++ b/OvmfPkg/ResetVector/Ia32/AmdSev.asm
@@ -177,12 +177,6 @@ pageTableEntries4kLoop:
     mov     ecx, (GHCB_BASE & 0x1F_FFFF) >> 12
     mov     [ecx * 8 + GHCB_PT_ADDR + 4], strict dword 0
 
-    mov     ecx, GHCB_SIZE / 4
-    xor     eax, eax
-clearGhcbMemoryLoop:
-    mov     dword[ecx * 4 + GHCB_BASE - 4], eax
-    loop    clearGhcbMemoryLoop
-
 SevClearPageEncMaskForGhcbPageExit:
     OneTimeCallRet SevClearPageEncMaskForGhcbPage
 
diff --git a/OvmfPkg/Sec/AmdSev.c b/OvmfPkg/Sec/AmdSev.c
index 27fd24fc13..0828d090fe 100644
--- a/OvmfPkg/Sec/AmdSev.c
+++ b/OvmfPkg/Sec/AmdSev.c
@@ -96,7 +96,7 @@ SevEsProtocolCheck (
   AsmWriteMsr64 (MSR_SEV_ES_GHCB, Msr.GhcbPhysicalAddress);
 
   Ghcb = Msr.Ghcb;
-  SetMem (Ghcb, sizeof (*Ghcb), 0);
+  SetMem (Ghcb, FixedPcdGet32 (PcdOvmfSecGhcbSize), 0);
 
   //
   // Set the version to the maximum that can be supported
-- 
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