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    SubjectRe: [PATCH] x86/efi: Access EFI MMIO data as unencrypted when SEV is active
    On 3 July 2018 at 15:32, Brijesh Singh <brijesh.singh@amd.com> wrote:
    > SEV guest fails to update the UEFI runtime variables stored in the
    > flash. 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.
    >
    > Fixes: 1379edd59673 (x86/efi: Access EFI data as encrypted ...)
    > Cc: Tom Lendacky <thomas.lendacky@amd.com>
    > Cc: Thomas Gleixner <tglx@linutronix.de>
    > Cc: Borislav Petkov <bp@suse.de>
    > Cc: linux-efi@vger.kernel.org
    > Cc: kvm@vger.kernel.org
    > Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
    > Cc: Matt Fleming <matt@codeblueprint.co.uk>
    > Cc: Andy Lutomirski <luto@kernel.org>
    > Cc: <stable@vger.kernel.org> # 4.15.x
    > Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
    > ---
    > arch/x86/platform/efi/efi_64.c | 2 +-
    > 1 file changed, 1 insertion(+), 1 deletion(-)
    >
    > 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;

    Is it safe to only update this occurrence and not the one in
    efi_runtime_update_mappings() ?

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