REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1281
This optimization has two purpose:
1. fix BZ#1281 which caused by flushing TLB for AP
2. improve performance for SMM heap guard
The code change is simple: just flush TLB for current processor.
Since processor's (including AP) SMI entry code will always initialize
CR3, it looks like that there's no need to add extra code in AP handler,
called from SMI entry, to flush TLB again.
Let each processor itself guarantee the TLB integrity can improve memory
operations performance if Heap Guard is enabled. This has been proved
by CpuDxe driver. Please check following patches for details.
41a9c3fd110bed93c4fdf088eea18412bb2dfcde
0dbb0f1a5ce6a9ec5213c85e5d4244cf5b061417
Stop flush TLB for APs (DXE) upon change
199de89677deffffff30eda7ad17793b30042cce
Let AP (DXE) flush TLB in its wake-up procedure
Tests:
a. Verified that issue in BZ#1281 is gone
b. Verified SMM heap guard works well on any processor
c. OVMF boot (Fedora26, Ubuntu18.04, Windows 10)
Cc: Eric Dong <[email protected]>
Cc: Laszlo Ersek <[email protected]>
Cc: Jiewen Yao <[email protected]>
Cc: Star Zeng <[email protected]>
Cc: Ruiyu Ni <[email protected]>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <[email protected]>
---
UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c | 45 +++-------------------
1 file changed, 6 insertions(+), 39 deletions(-)
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
index 684b14dc28..e0bf0cd5ac 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
@@ -464,41 +464,6 @@ ConvertMemoryPageAttributes (
return RETURN_SUCCESS;
}
-/**
- FlushTlb on current processor.
-
- @param[in,out] Buffer Pointer to private data buffer.
-**/
-VOID
-EFIAPI
-FlushTlbOnCurrentProcessor (
- IN OUT VOID *Buffer
- )
-{
- CpuFlushTlb ();
-}
-
-/**
- FlushTlb for all processors.
-**/
-VOID
-FlushTlbForAll (
- VOID
- )
-{
- UINTN Index;
-
- FlushTlbOnCurrentProcessor (NULL);
-
- for (Index = 0; Index < gSmst->NumberOfCpus; Index++) {
- if (Index != gSmst->CurrentlyExecutingCpu) {
- // Force to start up AP in blocking mode,
- SmmBlockingStartupThisAp (FlushTlbOnCurrentProcessor, Index, NULL);
- // Do not check return status, because AP might not be present in some
corner cases.
- }
- }
-}
-
/**
This function sets the attributes for the memory region specified by
BaseAddress and
Length from their current attributes to the attributes specified by
Attributes.
@@ -538,9 +503,10 @@ SmmSetMemoryAttributesEx (
if (!EFI_ERROR(Status)) {
if (IsModified) {
//
- // Flush TLB as last step
+ // Flush TLB as last step. No need to do it for APs, which sould take
care
+ // of it in the wake-up procedure.
//
- FlushTlbForAll();
+ CpuFlushTlb ();
}
}
@@ -586,9 +552,10 @@ SmmClearMemoryAttributesEx (
if (!EFI_ERROR(Status)) {
if (IsModified) {
//
- // Flush TLB as last step
+ // Flush TLB as last step. No need to do it for APs, which sould take
care
+ // of it in the wake-up procedure.
//
- FlushTlbForAll();
+ CpuFlushTlb ();
}
}
--
2.16.2.windows.1
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