[PATCH v3 08/16] ArmPkg/ArmMmuLib: take the CPU supported maximum PA space into account

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

In preparation of dropping PcdPrePiCpuMemorySize entirely, base the
maximum size of the identity map on the capabilities of the CPU.
Since that may exceed what is architecturally permitted when using
4 KB pages, take MAX_ADDRESS into account as well.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf       |  3 ---
 ArmPkg/Library/ArmMmuLib/ArmMmuPeiLib.inf        |  3 ---
 ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c | 11 +++++++++--
 3 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf b/ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf
index b9f264de8d26..246963361e45 100644
--- a/ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf
+++ b/ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf
@@ -40,8 +40,5 @@ [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 ecf13f790734..f689c193b862 100644
--- a/ArmPkg/Library/ArmMmuLib/ArmMmuPeiLib.inf
+++ b/ArmPkg/Library/ArmMmuLib/ArmMmuPeiLib.inf
@@ -35,6 +35,3 @@ [LibraryClasses]
   ArmLib
   CacheMaintenanceLib
   MemoryAllocationLib
-
-[Pcd.AARCH64]
-  gEmbeddedTokenSpaceGuid.PcdPrePiCpuMemorySize
diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
index 4b62ecb6a476..5403b8d4070e 100644
--- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
+++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
@@ -604,8 +604,15 @@ ArmConfigureMmu (
     return EFI_INVALID_PARAMETER;
   }
 
-  // Cover the entire GCD memory space
-  MaxAddress = (1UL << PcdGet8 (PcdPrePiCpuMemorySize)) - 1;
+  //
+  // Limit the virtual address space to what we can actually use: UEFI
+  // mandates a 1:1 mapping, so no point in making the virtual address
+  // space larger than the physical address space. We also have to take
+  // into account the architectural limitations that result from UEFI's
+  // use of 4 KB pages.
+  //
+  MaxAddress = MIN (LShiftU64 (1ULL, ArmGetPhysicalAddressBits ()) - 1,
+                    MAX_ADDRESS);
 
   // Lookup the Table Level to get the information
   LookupAddresstoRootTable (MaxAddress, &T0SZ, &RootTableEntryCount);
-- 
2.19.1