AmdSevDxe maps the flash memory range with C=0, but
SetMemorySpaceAttributes() unconditionally resets the C-bit to '1'. Lets
restore the mapping back to C=0.
Cc: Ard Biesheuvel <ard.biesheu...@linaro.org>
Cc: Anthony Perard <anthony.per...@citrix.com>
Cc: Julien Grall <julien.gr...@linaro.org>
Cc: Justen Jordan L <jordan.l.jus...@intel.com>
Cc: Laszlo Ersek <ler...@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Brijesh Singh <brijesh.si...@amd.com>
---
.../FvbServicesRuntimeDxe.inf | 1 +
.../QemuFlashFvbServicesRuntimeDxe/FwBlockServiceDxe.c | 17 +++++++++++++++++
2 files changed, 18 insertions(+)
diff --git a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf
b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf
index d7b4ec06c4e6..6bb5c2093790 100644
--- a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf
+++ b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf
@@ -54,6 +54,7 @@ [LibraryClasses]
DevicePathLib
DxeServicesTableLib
MemoryAllocationLib
+ MemEncryptSevLib
PcdLib
UefiBootServicesTableLib
UefiDriverEntryPoint
diff --git a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FwBlockServiceDxe.c
b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FwBlockServiceDxe.c
index 646427bf4e2c..3add4bbad74c 100644
--- a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FwBlockServiceDxe.c
+++ b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FwBlockServiceDxe.c
@@ -24,6 +24,7 @@
#include <Protocol/FirmwareVolumeBlock.h>
#include <Library/DxeServicesTableLib.h>
#include <Library/MemoryAllocationLib.h>
+#include <Library/MemEncryptSevLib.h>
#include "FwBlockService.h"
#include "QemuFlash.h"
@@ -204,5 +205,21 @@ MarkIoMemoryRangeForRuntimeAccess (
);
ASSERT_EFI_ERROR (Status);
+ //
+ // When SEV is active, AmdSevDxe should have mapped the BaseAddress with
+ // C=0 but SetMemorySpaceAttribute() remap the range with C=1. Lets restore
+ // the mapping so that both guest and hyervisor can access the flash
+ // memory range.
+ //
+ if (MemEncryptSevIsEnabled()) {
+ Status = MemEncryptSevClearPageEncMask (
+ 0,
+ BaseAddress,
+ EFI_SIZE_TO_PAGES (Length),
+ FALSE
+ );
+ ASSERT_EFI_ERROR (Status);
+ }
+
return Status;
}
--
2.7.4
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