[PATCH 4.17 17/31] x86/efi: Access EFI MMIO data as unencrypted when SEV is active

From: Greg Kroah-Hartman
Date: Sat Aug 04 2018 - 05:02:33 EST

4.17-stable review patch. If anyone has any objections, please let me know.


From: Brijesh Singh <brijesh.singh@xxxxxxx>

commit 9b788f32bee6b0b293a4bdfca4ad4bb0206407fb upstream.

SEV guest fails to update the UEFI runtime variables stored in the

The following commit:

1379edd59673 ("x86/efi: Access EFI data as encrypted when SEV is active")

unconditionally maps all the UEFI runtime data as 'encrypted' (C=1).

When SEV is active the UEFI runtime data marked as EFI_MEMORY_MAPPED_IO
should be mapped as 'unencrypted' so that both guest and hypervisor can
access the data.

Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Reviewed-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 4.15.x
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-efi@xxxxxxxxxxxxxxx
Fixes: 1379edd59673 ("x86/efi: Access EFI data as encrypted ...")
Link: http://lkml.kernel.org/r/20180720012846.23560-2-ard.biesheuvel@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

arch/x86/platform/efi/efi_64.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -417,7 +417,7 @@ static void __init __map_region(efi_memo
if (!(md->attribute & EFI_MEMORY_WB))
flags |= _PAGE_PCD;

- if (sev_active())
+ if (sev_active() && md->type != EFI_MEMORY_MAPPED_IO)
flags |= _PAGE_ENC;

pfn = md->phys_addr >> PAGE_SHIFT;