[PATCH v2] MdeModulePkg/UefiBootManagerLib: Match the nested partitions

[Gary Lin <glin@suse.com>]

In some cases, such as MD RAID1 in Linux, the bootloader may be in a
nested EFI system partition partition. For example, sda1 and sdb1 are
combined as md0 and the first partition of md0, md0p1, is an EFI system
partition. Then, the bootloader can be located by the following device
paths:

PCI()/SATA(sda)/Partition(sda1)/Partition(md0p1)/File(bootloader.efi)
PCI()/SATA(sdb)/Partition(sdb1)/Partition(md0p1)/File(bootloader.efi)

To make the boot option more resilient, we may create a boot option with
the short-form device path like "Partition(md0p1)/File(bootloader.efi)".

However, BmMatchPartitionDevicePathNode() only matched the first
partition node and ignored the nested partitions, so the firmware would
refuse to load bootloader.efi since "Partition(md0p1)" doesn't match
either "Partition(sda1)" or "Partition(sda2)".

This commit modifies BmMatchPartitionDevicePathNode() to iterate all
nested partitions so that the above boot option could work.

v2 - Simplify the node matching logic

Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao Wu <hao.a.wu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Gary Lin <glin@suse.com>
---
 .../Library/UefiBootManagerLib/BmBoot.c       | 38 +++++++++----------
 1 file changed, 17 insertions(+), 21 deletions(-)

diff --git a/MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c b/MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c
index 6a23477eb873..2284ce1a5646 100644
--- a/MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c
+++ b/MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c
@@ -1979,37 +1979,33 @@ BmMatchPartitionDevicePathNode (
   }
 
   //
-  // find the partition device path node
+  // Match all the partition device path nodes including the nested partition nodes
   //
   while (!IsDevicePathEnd (BlockIoDevicePath)) {
     if ((DevicePathType (BlockIoDevicePath) == MEDIA_DEVICE_PATH) &&
         (DevicePathSubType (BlockIoDevicePath) == MEDIA_HARDDRIVE_DP)
         ) {
-      break;
+      //
+      // See if the harddrive device path in blockio matches the orig Hard Drive Node
+      //
+      Node = (HARDDRIVE_DEVICE_PATH *) BlockIoDevicePath;
+
+      //
+      // Match Signature and PartitionNumber.
+      // Unused bytes in Signature are initiaized with zeros.
+      //
+      if ((Node->PartitionNumber == HardDriveDevicePath->PartitionNumber) &&
+          (Node->MBRType == HardDriveDevicePath->MBRType) &&
+          (Node->SignatureType == HardDriveDevicePath->SignatureType) &&
+          (CompareMem (Node->Signature, HardDriveDevicePath->Signature, sizeof (Node->Signature)) == 0)) {
+        return TRUE;
+      }
     }
 
     BlockIoDevicePath = NextDevicePathNode (BlockIoDevicePath);
   }
 
-  if (IsDevicePathEnd (BlockIoDevicePath)) {
-    return FALSE;
-  }
-
-  //
-  // See if the harddrive device path in blockio matches the orig Hard Drive Node
-  //
-  Node = (HARDDRIVE_DEVICE_PATH *) BlockIoDevicePath;
-
-  //
-  // Match Signature and PartitionNumber.
-  // Unused bytes in Signature are initiaized with zeros.
-  //
-  return (BOOLEAN) (
-    (Node->PartitionNumber == HardDriveDevicePath->PartitionNumber) &&
-    (Node->MBRType == HardDriveDevicePath->MBRType) &&
-    (Node->SignatureType == HardDriveDevicePath->SignatureType) &&
-    (CompareMem (Node->Signature, HardDriveDevicePath->Signature, sizeof (Node->Signature)) == 0)
-    );
+  return FALSE;
 }
 
 /**
-- 
2.20.1