[RFC PATCH 5/9] x86/efi: Unmap kernel-reserved boot regions from EFI page tables

[Ard Biesheuvel]

From: Ard Biesheuvel <ardb@xxxxxxxxxx>

Currently, the logic that unmaps boot services code and data regions
that were mapped temporarily to work around firmware bugs disregards
regions that have been marked as EFI_MEMORY_RUNTIME. However, such
regions only have significance to the OS, and there is no reason the
retain the mapping in the EFI page tables, given that the runtime
firmware must never touch those regions.

So pull the unmap forward.

Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
 arch/x86/platform/efi/quirks.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index 58d00ffb1d59..e72e8b23598e 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -442,12 +442,6 @@ void __init efi_unmap_boot_services(void)
 			continue;
 		}
 
-		/* Do not free, someone else owns it: */
-		if (md->attribute & EFI_MEMORY_RUNTIME) {
-			num_entries++;
-			continue;
-		}
-
 		/*
 		 * Before calling set_virtual_address_map(), EFI boot services
 		 * code/data regions were mapped as a quirk for buggy firmware.
@@ -455,6 +449,12 @@ void __init efi_unmap_boot_services(void)
 		 */
 		efi_unmap_pages(md);
 
+		/* Do not free, someone else owns it: */
+		if (md->attribute & EFI_MEMORY_RUNTIME) {
+			num_entries++;
+			continue;
+		}
+
 		/*
 		 * Nasty quirk: if all sub-1MB memory is used for boot
 		 * services, we can get here without having allocated the
-- 
2.53.0.473.g4a7958ca14-goog