Re: [PATCH] UefiCpuPkg: Update AESNI support checking logic

["Dong, Eric" <eric.dong@intel.com>]

Reviewed-by: Eric Dong <eric.dong@intel.com>

-----Original Message-----
From: Song, BinX 
Sent: Monday, December 25, 2017 11:11 AM
To: edk2-devel@lists.01.org
Cc: Dong, Eric <eric.dong@intel.com>; lersek@redhat.com
Subject: [PATCH] UefiCpuPkg: Update AESNI support checking logic

With correct model CPU, current checking logic will always execute AsmReadMsr64 operation and then check ECX.AESNI[bit 25] = 1. Update checking logic to check ECX.AESNI[bit 25] = 1 first and then do AsmReadMsr64 operation.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Bell Song <binx.song@intel.com>
---
 UefiCpuPkg/Library/CpuCommonFeaturesLib/Aesni.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/UefiCpuPkg/Library/CpuCommonFeaturesLib/Aesni.c b/UefiCpuPkg/Library/CpuCommonFeaturesLib/Aesni.c
index 880f092..56b1b55 100644
--- a/UefiCpuPkg/Library/CpuCommonFeaturesLib/Aesni.c
+++ b/UefiCpuPkg/Library/CpuCommonFeaturesLib/Aesni.c
@@ -62,15 +62,17 @@ AesniSupport (
 {
   MSR_SANDY_BRIDGE_FEATURE_CONFIG_REGISTER   *MsrFeatureConfig;
 
-  if (IS_SANDY_BRIDGE_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel) ||
-      IS_SILVERMONT_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel) ||
-      IS_XEON_5600_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel) ||
-      IS_XEON_E7_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel) ||
-      IS_XEON_PHI_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel)) {
-    MsrFeatureConfig = (MSR_SANDY_BRIDGE_FEATURE_CONFIG_REGISTER *) ConfigData;
-    ASSERT (MsrFeatureConfig != NULL);
-    MsrFeatureConfig[ProcessorNumber].Uint64 = AsmReadMsr64 (MSR_SANDY_BRIDGE_FEATURE_CONFIG);
-    return (CpuInfo->CpuIdVersionInfoEcx.Bits.AESNI == 1);
+  if (CpuInfo->CpuIdVersionInfoEcx.Bits.AESNI == 1) {
+    if (IS_SANDY_BRIDGE_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel) ||
+        IS_SILVERMONT_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel) ||
+        IS_XEON_5600_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel) ||
+        IS_XEON_E7_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel) ||
+        IS_XEON_PHI_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel)) {
+      MsrFeatureConfig = (MSR_SANDY_BRIDGE_FEATURE_CONFIG_REGISTER *) ConfigData;
+      ASSERT (MsrFeatureConfig != NULL);
+      MsrFeatureConfig[ProcessorNumber].Uint64 = AsmReadMsr64 (MSR_SANDY_BRIDGE_FEATURE_CONFIG);
+    }
+    return TRUE;
   }
   return FALSE;
 }
--
2.10.2.windows.1