UefiCpuPkg/CpuMpPei: Don't write CR3 in ConvertMemoryPageToNotPresent

The purpose of writing CR3 in ConvertMemoryPageToNotPresent is just
to flush TLB, because CR3 won't be changed in function
ConvertMemoryPageToNotPresent.
After ConvertMemoryPageToNotPresent, there is always a flush TLB
function. Also, because ConvertMemoryPageToNotPresent in called in a
loop, to improve performance, there is no need to flush TLB
inside ConvertMemoryPageToNotPresent. Just flushing TLB after the loop
is enough.

Reviewed-by: Ray Ni <ray.ni@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Zhiguang Liu <zhiguang.liu@intel.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/UefiCpuPkg/CpuMpPei/CpuPaging.c b/UefiCpuPkg/CpuMpPei/CpuPaging.c
index 15c7015..b923d9b 100644
--- a/UefiCpuPkg/CpuMpPei/CpuPaging.c
+++ b/UefiCpuPkg/CpuMpPei/CpuPaging.c
@@ -76,7 +76,8 @@ AllocatePageTableMemory (
 

 /**

   This function modifies the page attributes for the memory region specified

-  by BaseAddress and Length to not present.

+  by BaseAddress and Length to not present. This function only change page

+  table, but not flush TLB. Caller have the responsbility to flush TLB.

 

   Caller should make sure BaseAddress and Length is at page boundary.

 

@@ -167,7 +168,6 @@ ConvertMemoryPageToNotPresent (
   }

 

   ASSERT_EFI_ERROR (Status);

-  AsmWriteCr3 (PageTable);

   return Status;

 }