From 9596c779a27b4ae2261aadd91b8dac8ed7546f38 Mon Sep 17 00:00:00 2001
From: Neal Gompa <ngompa@fedoraproject.org>
Date: Mon, 5 Jul 2021 05:36:03 -0400
Subject: [PATCH] MdeModulePkg/PartitionDxe: Ignore PMBR BootIndicator per UEFI
 spec
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RH-Author: Philippe Mathieu-Daudé <philmd@redhat.com>
RH-MergeRequest: 6: MdeModulePkg/PartitionDxe: Ignore PMBR BootIndicator per UEFI spec [rhel-8.5.0, post-rebase]
RH-Commit: [1/1] 1fef74489947c81e26e5afb7c933c80beb641751
RH-Bugzilla: 1988762
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

Per UEFI Spec 2.8 (UEFI_Spec_2_8_final.pdf, page 114)
5.2.3 Protective MBR
Table 20. Protective MBR Partition Record protecting the entire disk

The description for BootIndicator states the following:

> Set to 0x00 to indicate a non-bootable partition. If set to any
> value other than 0x00 the behavior of this flag on non-UEFI
> systems is undefined. Must be ignored by UEFI implementations.

Unfortunately, we have been incorrectly assuming that the
BootIndicator value must be 0x00, which leads to problems
when the 'pmbr_boot' flag is set on a disk containing a GPT
(such as with GNU parted). When the flag is set, the value
changes to 0x01, causing this check to fail and the system
is rendered unbootable despite it being valid from the
perspective of the UEFI spec.

To resolve this, we drop the check for the BootIndicator
so that we stop caring about the value set there, which
restores the capability to boot such disks.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3474

Cc: Chris Murphy <chrismurphy@fedoraproject.org>
Cc: David Duncan <davdunc@amazon.com>
Cc: Lazlo Ersek <lersek@redhat.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Zhichao Gao <zhichao.gao@intel.com>

Signed-off-by: Neal Gompa <ngompa@fedoraproject.org>
Message-Id: <20210705093603.575707-1-ngompa@fedoraproject.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>
(cherry picked from commit b3db0cb1f8d163f22b769c205c6347376a315dcd)
Signed-off-by: Philippe Mathieu-Daude <philmd@redhat.com>
---
 MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c b/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
index aefb2d6ecb..efaff5e080 100644
--- a/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
+++ b/MdeModulePkg/Universal/Disk/PartitionDxe/Gpt.c
@@ -264,8 +264,7 @@ PartitionInstallGptChildHandles (
   // Verify that the Protective MBR is valid
   //
   for (Index = 0; Index < MAX_MBR_PARTITIONS; Index++) {
-    if (ProtectiveMbr->Partition[Index].BootIndicator == 0x00 &&
-        ProtectiveMbr->Partition[Index].OSIndicator == PMBR_GPT_PARTITION &&
+    if (ProtectiveMbr->Partition[Index].OSIndicator == PMBR_GPT_PARTITION &&
         UNPACK_UINT32 (ProtectiveMbr->Partition[Index].StartingLBA) == 1
         ) {
       break;
-- 
2.27.0