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..86b244a0095b 100644 --- a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf +++ b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf @@ -53,6 +53,7 @@ [LibraryClasses] DebugLib DevicePathLib DxeServicesTableLib + MemEncryptSevLib MemoryAllocationLib PcdLib UefiBootServicesTableLib diff --git a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FwBlockServiceDxe.c b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FwBlockServiceDxe.c index 37deece363e6..1fbe1342a57c 100644 --- a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FwBlockServiceDxe.c +++ b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FwBlockServiceDxe.c @@ -18,6 +18,7 @@ #include <Library/DebugLib.h> #include <Library/DevicePathLib.h> #include <Library/DxeServicesTableLib.h> +#include <Library/MemEncryptSevLib.h> #include <Library/PcdLib.h> #include <Library/UefiBootServicesTableLib.h> #include <Library/UefiRuntimeLib.h> @@ -203,5 +204,21 @@ MarkIoMemoryRangeForRuntimeAccess ( ); ASSERT_EFI_ERROR (Status); + // + // When SEV is active, AmdSevDxe mapped the BaseAddress with C=0 but + // SetMemorySpaceAttributes() remaps the range with C=1. Let's 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 _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel