x86/efi: Access EFI MMIO data as unencrypted when SEV is active

9b788f32 · Brijesh Singh <[email protected]> · 2018-07-20 10:28:46 +09:00

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

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 <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
Reviewed-by: Tom Lendacky <[email protected]>
Cc: <[email protected]> # 4.15.x
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Fixes: 1379edd59673 ("x86/efi: Access EFI data as encrypted ...")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

Commit: 9b788f32bee6b0b293a4bdfca4ad4bb0206407fb
Parents: 45ae4df9

Changes

1 files changed · +1 −1

File	Status	Add	Del	Content
arch/x86/platform/efi/efi_64.c	modified	+1	−1	View file

arch/x86/platform/efi/efi_64.c

View file

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 77873ce..5f2eb32 100644
--- 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_memory_desc_t *md, u64 va)
 	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;