[PATCH v4 2/2] ArmPkg/ArmMmuLib AARCH64: invalidate page tables before populating them

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

As it turns out, ARMv8 also permits accesses made with the MMU and
caches off to hit in the caches, so to ensure that any modifications
we make before enabling the MMU are visible afterwards as well, we
should invalidate page tables right after allocation like we do now on
ARM, if the MMU is still disabled at that point.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif@nuviainc.com>
---
 ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
index 00a38bc31d0a..221175ca6535 100644
--- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
+++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
@@ -204,6 +204,14 @@ UpdateRegionMappingRecursive (
           return EFI_OUT_OF_RESOURCES;
         }
 
+        if (!ArmMmuEnabled ()) {
+          //
+          // Make sure we are not inadvertently hitting in the caches
+          // when populating the page tables.
+          //
+          InvalidateDataCacheRange (TranslationTable, EFI_PAGE_SIZE);
+        }
+
         if ((*Entry & TT_TYPE_MASK) == TT_TYPE_BLOCK_ENTRY) {
           //
           // We are splitting an existing block entry, so we have to populate
@@ -602,6 +610,12 @@ ArmConfigureMmu (
     *TranslationTableSize = RootTableEntryCount * sizeof(UINT64);
   }
 
+  //
+  // Make sure we are not inadvertently hitting in the caches
+  // when populating the page tables.
+  //
+  InvalidateDataCacheRange (TranslationTable,
+    RootTableEntryCount * sizeof(UINT64));
   ZeroMem (TranslationTable, RootTableEntryCount * sizeof(UINT64));
 
   TranslationTableAttribute = TT_ATTR_INDX_INVALID;
-- 
2.17.1