[PATCH] IntelSiliconPkg VTdDxe: Option to force no early access attr request

* [PATCH] IntelSiliconPkg VTdDxe: Option to force no early access attr request
@ 2018-10-24  3:31 Star Zeng
  2018-10-24 11:22 ` Yao, Jiewen
  0 siblings, 1 reply; 2+ messages in thread
From: Star Zeng @ 2018-10-24  3:31 UTC (permalink / raw)
  To: edk2-devel; +Cc: Star Zeng, Jiewen Yao, Rangasai V Chaganty

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1272

To have high confidence in usage for platform, add option (BIT2 of
PcdVTdPolicyPropertyMask) to force no IOMMU access attribute request
recording before DMAR table is installed.

Check PcdVTdPolicyPropertyMask BIT2 before RequestAccessAttribute()
and ProcessRequestedAccessAttribute(), then RequestAccessAttribute(),
ProcessRequestedAccessAttribute() and mAccessRequestXXX variables
could be optimized by compiler when PcdVTdPolicyPropertyMask BIT2 = 1.

Test done:
1: Created case that has IOMMU access attribute request before DMAR
   table is installed, ASSERT was triggered after setting
   PcdVTdPolicyPropertyMask BIT2 to 1.

2. Confirmed RequestAccessAttribute(), ProcessRequestedAccessAttribute()
   and mAccessRequestXXX variables were optimized by compiler after
   setting PcdVTdPolicyPropertyMask BIT2 to 1.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Rangasai V Chaganty <rangasai.v.chaganty@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Star Zeng <star.zeng@intel.com>
---
 IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c | 8 +++++++-
 IntelSiliconPkg/Feature/VTd/IntelVTdDxe/IntelVTdDxe.c   | 7 +++++++
 IntelSiliconPkg/IntelSiliconPkg.dec                     | 1 +
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c b/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c
index 86d50eb6f288..7784545631b3 100644
--- a/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c
+++ b/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c
@@ -515,7 +515,13 @@ SetupVtd (
 
   ParseDmarAcpiTableRmrr ();
 
-  ProcessRequestedAccessAttribute ();
+  if ((PcdGet8 (PcdVTdPolicyPropertyMask) & BIT2) == 0) {
+    //
+    // Support IOMMU access attribute request recording before DMAR table is installed.
+    // Here is to process the requests.
+    //
+    ProcessRequestedAccessAttribute ();
+  }
 
   for (Index = 0; Index < mVtdUnitNumber; Index++) {
     DEBUG ((DEBUG_INFO,"VTD Unit %d (Segment: %04x)\n", Index, mVtdUnitInformation[Index].Segment));
diff --git a/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/IntelVTdDxe.c b/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/IntelVTdDxe.c
index 25d7c80af1d4..09948ce50e94 100644
--- a/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/IntelVTdDxe.c
+++ b/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/IntelVTdDxe.c
@@ -254,6 +254,13 @@ VTdSetAttribute (
     // Record the entry to driver global variable.
     // As such once VTd is activated, the setting can be adopted.
     //
+    if ((PcdGet8 (PcdVTdPolicyPropertyMask) & BIT2) != 0) {
+      //
+      // Force no IOMMU access attribute request recording before DMAR table is installed.
+      //
+      ASSERT_EFI_ERROR (EFI_NOT_READY);
+      return EFI_NOT_READY;
+    }
     Status = RequestAccessAttribute (Segment, SourceId, DeviceAddress, Length, IoMmuAccess);
   } else {
     PERF_CODE (
diff --git a/IntelSiliconPkg/IntelSiliconPkg.dec b/IntelSiliconPkg/IntelSiliconPkg.dec
index b9646d773b95..900e8f63c64d 100644
--- a/IntelSiliconPkg/IntelSiliconPkg.dec
+++ b/IntelSiliconPkg/IntelSiliconPkg.dec
@@ -64,6 +64,7 @@ [PcdsFixedAtBuild, PcdsPatchableInModule, PcdsDynamic, PcdsDynamicEx]
   ## The mask is used to control VTd behavior.<BR><BR>
   #  BIT0: Enable IOMMU during boot (If DMAR table is installed in DXE. If VTD_INFO_PPI is installed in PEI.)
   #  BIT1: Enable IOMMU when transfer control to OS (ExitBootService in normal boot. EndOfPEI in S3)
+  #  BIT2: Force no IOMMU access attribute request recording before DMAR table is installed.
   # @Prompt The policy for VTd driver behavior.
   gIntelSiliconPkgTokenSpaceGuid.PcdVTdPolicyPropertyMask|1|UINT8|0x00000002
 
-- 
2.7.0.windows.1



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