[PATCH] ArmPkg/ArmMmuLib: base page table VA size on GCD memory map size

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

As reported by Eugene, the practice of sizing the address space in the
virtual memory system based on the maximum address in the table passed
to ArmConfigureMmu() is problematic, since it fails to take into account
the fact that the GCD memory space may be extended at a later time, both
for memory and for MMIO. So instead, choose the VA size identical to the
GCD memory map size, which is based on PcdPrePiCpuMemorySize on ARM
systems.

Reported-by: Eugene Cohen <eugene@hp.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c | 14 ++------------
 ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf       |  4 ++++
 ArmPkg/Library/ArmMmuLib/ArmMmuPeiLib.inf        |  4 ++++
 3 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
index 6e05e6085011..b5900a761f80 100644
--- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
+++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
@@ -582,9 +582,7 @@ ArmConfigureMmu (
   VOID*                         TranslationTable;
   UINTN                         TranslationTablePageCount;
   UINT32                        TranslationTableAttribute;
-  ARM_MEMORY_REGION_DESCRIPTOR *MemoryTableEntry;
   UINT64                        MaxAddress;
-  UINT64                        TopAddress;
   UINTN                         T0SZ;
   UINTN                         RootTableEntryCount;
   UINT64                        TCR;
@@ -595,16 +593,8 @@ ArmConfigureMmu (
     return RETURN_INVALID_PARAMETER;
   }
 
-  // Identify the highest address of the memory table
-  MaxAddress = MemoryTable->PhysicalBase + MemoryTable->Length - 1;
-  MemoryTableEntry = MemoryTable;
-  while (MemoryTableEntry->Length != 0) {
-    TopAddress = MemoryTableEntry->PhysicalBase + MemoryTableEntry->Length - 1;
-    if (TopAddress > MaxAddress) {
-      MaxAddress = TopAddress;
-    }
-    MemoryTableEntry++;
-  }
+  // Cover the entire GCD memory space
+  MaxAddress = (1UL << PcdGet8 (PcdPrePiCpuMemorySize)) - 1;
 
   // Lookup the Table Level to get the information
   LookupAddresstoRootTable (MaxAddress, &T0SZ, &RootTableEntryCount);
diff --git a/ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf b/ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf
index 1533c2944e8e..b9f264de8d26 100644
--- a/ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf
+++ b/ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf
@@ -32,6 +32,7 @@ [Sources.ARM]
 
 [Packages]
   ArmPkg/ArmPkg.dec
+  EmbeddedPkg/EmbeddedPkg.dec
   MdePkg/MdePkg.dec
 
 [LibraryClasses]
@@ -39,5 +40,8 @@ [LibraryClasses]
   CacheMaintenanceLib
   MemoryAllocationLib
 
+[Pcd.AARCH64]
+  gEmbeddedTokenSpaceGuid.PcdPrePiCpuMemorySize
+
 [Pcd.ARM]
   gArmTokenSpaceGuid.PcdNormalMemoryNonshareableOverride
diff --git a/ArmPkg/Library/ArmMmuLib/ArmMmuPeiLib.inf b/ArmPkg/Library/ArmMmuLib/ArmMmuPeiLib.inf
index 14ebf8de673d..ecf13f790734 100644
--- a/ArmPkg/Library/ArmMmuLib/ArmMmuPeiLib.inf
+++ b/ArmPkg/Library/ArmMmuLib/ArmMmuPeiLib.inf
@@ -28,9 +28,13 @@ [Sources.AARCH64]
 
 [Packages]
   ArmPkg/ArmPkg.dec
+  EmbeddedPkg/EmbeddedPkg.dec
   MdePkg/MdePkg.dec
 
 [LibraryClasses]
   ArmLib
   CacheMaintenanceLib
   MemoryAllocationLib
+
+[Pcd.AARCH64]
+  gEmbeddedTokenSpaceGuid.PcdPrePiCpuMemorySize
-- 
2.7.4