From 8c09f300103993985c91532239a72ba879df0b31 Mon Sep 17 00:00:00 2001
From: Star Zeng <star.zeng@intel.com>
Date: Wed, 17 Oct 2018 17:43:28 +0800
Subject: [PATCH] IntelSiliconPkg VTdDxe: Option to force no early access attr
 request

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>
Reviewed-by: Jiewen Yao <jiewen.yao@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 86d50eb6f2..7784545631 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 25d7c80af1..09948ce50e 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 c0cf58fa6c..2f5bef6089 100644
--- a/IntelSiliconPkg/IntelSiliconPkg.dec
+++ b/IntelSiliconPkg/IntelSiliconPkg.dec
@@ -58,6 +58,7 @@
   ## 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