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

------------------

From: Brijesh Singh <[email protected]>

commit 9b788f32bee6b0b293a4bdfca4ad4bb0206407fb upstream.

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]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 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;


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