OvmfPkg: allocate the EFI memory map for Linux as Loader Data

In Linux, efi_memblock_x86_reserve_range() and efi_reserve_boot_services()
expect that whoever allocates the EFI memmap allocates it in Loader Data
type memory. Linux's own exit_boot()-->low_alloc() complies, but
SetupLinuxMemmap() in LoadLinuxLib doesn't.

The memory type discrepancy leads to efi_memblock_x86_reserve_range() and
efi_reserve_boot_services() both trying to reserve the range backing the
memmap, resulting in memmap entry truncation in
efi_reserve_boot_services().

This fix also makes this allocation consistent with all other persistent
allocations in  "OvmfPkg/Library/LoadLinuxLib/Linux.c".

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reported-and-tested-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14555 6f19259b-4bc3-4df7-8a09-765794883524

OvmfPkg/Library/LoadLinuxLib/Linux.c

@@ -280,8 +280,12 @@ SetupLinuxMemmap (
   // Enlarge space here, because we will allocate pool now.
   //
   MemoryMapSize += EFI_PAGE_SIZE;
-  MemoryMap = AllocatePool (MemoryMapSize);
-  ASSERT (MemoryMap != NULL);
+  Status = gBS->AllocatePool (
+                  EfiLoaderData,
+                  MemoryMapSize,
+                  (VOID **) &MemoryMap
+                  );
+  ASSERT_EFI_ERROR (Status);
 
   //
   // Get System MemoryMap