From 7812e5caab4c5de06a0e80afe6c871884017519f Mon Sep 17 00:00:00 2001
From: Laszlo Ersek <lersek@redhat.com>
Date: Tue, 28 Nov 2017 18:09:48 +0100
Subject: [PATCH 2/3] MdeModulePkg/DxeCore: Filter out all paging capabilities

Message-id: <20171128170949.14548-3-lersek@redhat.com>
Patchwork-id: 77944
O-Subject:  [RHEL-7.5 ovmf PATCH 2/3] MdeModulePkg/DxeCore: Filter out all paging
	capabilities
Bugzilla: 1518308
Acked-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Acked-by: Thomas Huth <thuth@redhat.com>

From: Jian J Wang <jian.j.wang@intel.com>

Some OSs will treat EFI_MEMORY_DESCRIPTOR.Attribute as really
set attributes and change memory paging attribute accordingly.
But current EFI_MEMORY_DESCRIPTOR.Attribute is assigned by
value from Capabilities in GCD memory map. This might cause
boot problems. Clearing all paging related capabilities can
workaround it. The code added in this patch is supposed to
be removed once the usage of EFI_MEMORY_DESCRIPTOR.Attribute
is clarified in UEFI spec and adopted by both EDK-II Core and
all supported OSs.

Laszlo did a thorough test on OVMF emulated platform. The details
can be found at
    https://bugzilla.tianocore.org/show_bug.cgi?id=753#c10

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
(cherry picked from commit e38451cd9a87f86d9c699281252d381e10dcc98e)
---
 MdeModulePkg/Core/Dxe/Mem/Page.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/MdeModulePkg/Core/Dxe/Mem/Page.c b/MdeModulePkg/Core/Dxe/Mem/Page.c
index 3dd6d1b..fb149e4 100644
--- a/MdeModulePkg/Core/Dxe/Mem/Page.c
+++ b/MdeModulePkg/Core/Dxe/Mem/Page.c
@@ -1618,6 +1618,7 @@ CoreGetMemoryMap (
   EFI_GCD_MAP_ENTRY                 MergeGcdMapEntry;
   EFI_MEMORY_TYPE                   Type;
   EFI_MEMORY_DESCRIPTOR             *MemoryMapStart;
+  EFI_MEMORY_DESCRIPTOR             *MemoryMapEnd;
 
   //
   // Make sure the parameters are valid
@@ -1827,6 +1828,25 @@ CoreGetMemoryMap (
   //
   BufferSize = ((UINT8 *)MemoryMap - (UINT8 *)MemoryMapStart);
 
+  //
+  // Note: Some OSs will treat EFI_MEMORY_DESCRIPTOR.Attribute as really
+  //       set attributes and change memory paging attribute accordingly.
+  //       But current EFI_MEMORY_DESCRIPTOR.Attribute is assigned by
+  //       value from Capabilities in GCD memory map. This might cause
+  //       boot problems. Clearing all paging related capabilities can
+  //       workaround it. Following code is supposed to be removed once
+  //       the usage of EFI_MEMORY_DESCRIPTOR.Attribute is clarified in
+  //       UEFI spec and adopted by both EDK-II Core and all supported
+  //       OSs.
+  //
+  MemoryMapEnd = MemoryMap;
+  MemoryMap = MemoryMapStart;
+  while (MemoryMap < MemoryMapEnd) {
+    MemoryMap->Attribute &= ~(UINT64)(EFI_MEMORY_RP | EFI_MEMORY_RO |
+                                      EFI_MEMORY_XP);
+    MemoryMap = NEXT_MEMORY_DESCRIPTOR (MemoryMap, Size);
+  }
+
   Status = EFI_SUCCESS;
 
 Done:
-- 
1.8.3.1