From bec9104201296e4161862a18f0ce3a3d376e68de Mon Sep 17 00:00:00 2001
From: Min Xu <min.m.xu@intel.com>
Date: Mon, 18 Oct 2021 13:06:59 +0800
Subject: MdeModulePkg: Skip setting IA32_ERER.NXE if it has already been set

RFC: https://bugzilla.tianocore.org/show_bug.cgi?id=3429

If IA32_ERER.NXE has already been set, skip setting it again.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Min Xu <min.m.xu@intel.com>
---
 MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

(limited to 'MdeModulePkg/Core')

diff --git a/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c b/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
index 1ebab27820..a451ca1604 100644
--- a/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
+++ b/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
@@ -179,9 +179,11 @@ EnableExecuteDisableBit (
 {
   UINT64  MsrRegisters;
 
-  MsrRegisters  = AsmReadMsr64 (0xC0000080);
-  MsrRegisters |= BIT11;
-  AsmWriteMsr64 (0xC0000080, MsrRegisters);
+  MsrRegisters = AsmReadMsr64 (0xC0000080);
+  if ((MsrRegisters & BIT11) == 0) {
+    MsrRegisters |= BIT11;
+    AsmWriteMsr64 (0xC0000080, MsrRegisters);
+  }
 }
 
 /**
-- 
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