Re: [edk2-devel] [PATCH V9 35/47] MdeModulePkg: Skip setting IA32_ERER.NXE if it has already been set

["Ni, Ray" <ray.ni@intel.com>]

Reviewed-by: Ray Ni <ray.ni@Intel.com>

-----Original Message-----
From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Min Xu
Sent: Friday, March 18, 2022 8:46 AM
To: devel@edk2.groups.io
Cc: Xu, Min M <min.m.xu@intel.com>; Wang, Jian J <jian.j.wang@intel.com>; Wu, Hao A <hao.a.wu@intel.com>; Brijesh Singh <brijesh.singh@amd.com>; Aktas, Erdem <erdemaktas@google.com>; James Bottomley <jejb@linux.ibm.com>; Yao, Jiewen <jiewen.yao@intel.com>; Tom Lendacky <thomas.lendacky@amd.com>; Gerd Hoffmann <kraxel@redhat.com>
Subject: [edk2-devel] [PATCH V9 35/47] 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>
Signed-off-by: Min Xu <min.m.xu@intel.com>
---
 MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c b/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
index 1ebab2782010..a451ca160408 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);
+  }
 }
 
 /**
-- 
2.29.2.windows.2