UefiCpuPkg MTRR Library: enhance MTRR Library.

When it finds that a request range is covered by an existing MTRR with same cache type, the MTRR library set a flag and continues to check other MTRRs and invalidate any MTRR of the same request range with a higher-priority cache type.

Signed-off-by: rsun3
Reviewed-by: gxing


git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12388 6f19259b-4bc3-4df7-8a09-765794883524

1 files changed, 12 insertions, 4 deletions

diff --git a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
index edb75c04a..04c6a1c26 100644
--- a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
+++ b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
@@ -477,10 +477,12 @@ CombineMemoryAttribute (
   UINT64  MtrrEnd;

   UINT64  EndAddress;

   UINT32  FirmwareVariableMtrrCount;

+  BOOLEAN CoveredByExistingMtrr;

 

   FirmwareVariableMtrrCount = GetFirmwareVariableMtrrCount ();

 

   *OverwriteExistingMtrr = FALSE;

+  CoveredByExistingMtrr = FALSE;

   EndAddress = *Base +*Length - 1;

 

   for (Index = 0; Index < FirmwareVariableMtrrCount; Index++) {

@@ -501,11 +503,12 @@ CombineMemoryAttribute (
     //

     if (Attributes == VariableMtrr[Index].Type) {

       //

-      // if the Mtrr range contain the request range, return RETURN_SUCCESS

+      // if the Mtrr range contain the request range, set a flag, then continue to 

+      // invalidate any MTRR of the same request range with higher priority cache type.

       //

       if (VariableMtrr[Index].BaseAddress <= *Base && MtrrEnd >= EndAddress) {

-        *Length = 0;

-        return RETURN_SUCCESS;

+        CoveredByExistingMtrr = TRUE;

+        continue;

       }

       //

       // invalid this MTRR, and program the combine range

@@ -552,6 +555,10 @@ CombineMemoryAttribute (
     return RETURN_ACCESS_DENIED;

   }

 

+  if (CoveredByExistingMtrr) {

+    *Length = 0;

+  }

+

   return RETURN_SUCCESS;

 }

 

@@ -1007,8 +1014,9 @@ MtrrSetMemoryAttribute (
 

     if (Length == 0) {

       //

-      // Combined successfully

+      // Combined successfully, invalidate the now-unused MTRRs

       //

+      InvalidateMtrr(VariableMtrr);

       Status = RETURN_SUCCESS;

       goto Done;

     }