[1/1] x86/efi: Access EFI MMIO data as unencrypted when SEV is active

Message ID 20180720012846.23560-2-ard.biesheuvel@linaro.org
State New
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Series
  • [1/1] x86/efi: Access EFI MMIO data as unencrypted when SEV is active
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Commit Message

Ard Biesheuvel July 20, 2018, 1:28 a.m.
From: Brijesh Singh <brijesh.singh@amd.com>


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: <stable@vger.kernel.org> # 4.15.x
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

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

-- 
2.17.1

Patch

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 77873ce700ae..5f2eb3231607 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;