From f6d83cd74def6af6ab27ddda15112cdf59c853d5 Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Mon, 16 Jan 2023 10:46:39 +0100
Subject: [PATCH] ArmVirt: don't use unaligned CopyMem () on NOR flash

RH-Author: Gerd Hoffmann <kraxel@redhat.com>
RH-MergeRequest: 23: ArmVirt: don't use unaligned CopyMem () on NOR flash
RH-Bugzilla: 2158173
RH-Acked-by: Oliver Steffen <osteffen@redhat.com>
RH-Commit: [1/1] 7c8b7e5cd9c239dd8d040450bd4d479ef789114b (kraxel/centos-edk2)

Commit 789a72328553 reclassified the NOR flash region as EFI_MEMORY_WC
in the OS visible EFI memory map, and dropped the explicit aligned
CopyMem() implementation, in the assumption that EFI_MEMORY_WC will be
honored by the OS, and that the region will be mapped in a way that
tolerates misaligned accesseses. However, Linux today uses device
attributes for all EFI MMIO regions, in spite of the memory type
attributes, and so using misaligned accesses is never safe.

So instead, switch to the generic CopyMem() implementation entirely,
just like we already did for VariableRuntimeDxe.

Fixes: 789a72328553 ("OvmfPkg/VirtNorFlashDxe: use EFI_MEMORY_WC and drop AlignedCopyMem()")
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
(cherry picked from commit 987cc09c7cf38d628063062483e2341fba679b0e)
---
 ArmVirtPkg/ArmVirtKvmTool.dsc    | 6 +++++-
 ArmVirtPkg/ArmVirtQemu.dsc       | 6 +++++-
 ArmVirtPkg/ArmVirtQemuKernel.dsc | 6 +++++-
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/ArmVirtPkg/ArmVirtKvmTool.dsc b/ArmVirtPkg/ArmVirtKvmTool.dsc
index 2ba00bd08f..d0afe1b49e 100644
--- a/ArmVirtPkg/ArmVirtKvmTool.dsc
+++ b/ArmVirtPkg/ArmVirtKvmTool.dsc
@@ -296,7 +296,11 @@
       NULL|ArmVirtPkg/Library/ArmVirtTimerFdtClientLib/ArmVirtTimerFdtClientLib.inf
   }
 
-  OvmfPkg/VirtNorFlashDxe/VirtNorFlashDxe.inf
+  OvmfPkg/VirtNorFlashDxe/VirtNorFlashDxe.inf {
+    <LibraryClasses>
+      # don't use unaligned CopyMem () on the UEFI varstore NOR flash region
+      BaseMemoryLib|MdePkg/Library/BaseMemoryLib/BaseMemoryLib.inf
+  }
 
   MdeModulePkg/Universal/WatchdogTimerDxe/WatchdogTimer.inf
 
diff --git a/ArmVirtPkg/ArmVirtQemu.dsc b/ArmVirtPkg/ArmVirtQemu.dsc
index a4bd72e481..76389e6bd4 100644
--- a/ArmVirtPkg/ArmVirtQemu.dsc
+++ b/ArmVirtPkg/ArmVirtQemu.dsc
@@ -428,7 +428,11 @@
     <LibraryClasses>
       NULL|ArmVirtPkg/Library/ArmVirtTimerFdtClientLib/ArmVirtTimerFdtClientLib.inf
   }
-  OvmfPkg/VirtNorFlashDxe/VirtNorFlashDxe.inf
+  OvmfPkg/VirtNorFlashDxe/VirtNorFlashDxe.inf {
+    <LibraryClasses>
+      # don't use unaligned CopyMem () on the UEFI varstore NOR flash region
+      BaseMemoryLib|MdePkg/Library/BaseMemoryLib/BaseMemoryLib.inf
+  }
   MdeModulePkg/Universal/WatchdogTimerDxe/WatchdogTimer.inf
 
   #
diff --git a/ArmVirtPkg/ArmVirtQemuKernel.dsc b/ArmVirtPkg/ArmVirtQemuKernel.dsc
index 7f85b0dc92..0445a89b1c 100644
--- a/ArmVirtPkg/ArmVirtQemuKernel.dsc
+++ b/ArmVirtPkg/ArmVirtQemuKernel.dsc
@@ -331,7 +331,11 @@
     <LibraryClasses>
       NULL|ArmVirtPkg/Library/ArmVirtTimerFdtClientLib/ArmVirtTimerFdtClientLib.inf
   }
-  OvmfPkg/VirtNorFlashDxe/VirtNorFlashDxe.inf
+  OvmfPkg/VirtNorFlashDxe/VirtNorFlashDxe.inf {
+    <LibraryClasses>
+      # don't use unaligned CopyMem () on the UEFI varstore NOR flash region
+      BaseMemoryLib|MdePkg/Library/BaseMemoryLib/BaseMemoryLib.inf
+  }
   MdeModulePkg/Universal/WatchdogTimerDxe/WatchdogTimer.inf
 
   #
-- 
2.31.1