Based on the following patch from Brijesh Singh <brijesh.singh@amd.com>:
[PATCH v2 1/2] OvmfPkg/AmdSevDxe: Clear the C-bit from SMM Saved State
http://mid.mail-archive.com/20180228161415.28723-2-brijesh.singh@amd.comhttps://lists.01.org/pipermail/edk2-devel/2018-February/022016.html
Original commit message from Brijesh:
> When OVMF is built with SMM, SMMSaved State area (SMM_DEFAULT_SMBASE +
> SMRAM_SAVE_STATE_MAP_OFFSET) contains data which need to be accessed by
> both guest and hypervisor. Since the data need to be accessed by both
> hence we must map the SMMSaved State area as unencrypted (i.e C-bit
> cleared).
>
> This patch clears the SavedStateArea address before SMBASE relocation.
> Currently, we do not clear the SavedStateArea address after SMBASE is
> relocated due to the following reasons:
>
> 1) Guest BIOS never access the relocated SavedStateArea.
>
> 2) The C-bit works on page-aligned address, but the SavedStateArea
> address is not a page-aligned. Theoretically, we could roundup the
> address and clear the C-bit of aligned address but looking carefully we
> found that some portion of the page contains code -- which will causes a
> bigger issue for the SEV guest. When SEV is enabled, all the code must
> be encrypted otherwise hardware will cause trap.
Changes by Laszlo:
- separate AmdSevDxe bits from SmmCpuFeaturesLib bits;
- spell out PcdLib dependency with #include and in LibraryClasses;
- replace (SMM_DEFAULT_SMBASE + SMRAM_SAVE_STATE_MAP_OFFSET) calculation
with call to new MemEncryptSevLocateInitialSmramSaveStateMapPages()
function;
- consequently, pass page-aligned BaseAddress to
MemEncryptSevClearPageEncMask();
- zero the pages before clearing the C-bit;
- pass Flush=TRUE to MemEncryptSevClearPageEncMask();
- harden the treatment of MemEncryptSevClearPageEncMask() failure.
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
List those and only those libraries that are used.
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
There are many overlong lines; it's hard to work with the module like
this. Rewrap all files to 79 columns.
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
When SEV is enabled, the MMIO memory range must be mapped as unencrypted
(i.e C-bit cleared).
We need to clear the C-bit for MMIO GCD entries in order to cover the
ranges that were added during the PEI phase (through memory resource
descriptor HOBs). Additionally, the NonExistent ranges are processed
in order to cover, in advance, MMIO ranges added later in the DXE phase
by various device drivers, via the appropriate DXE memory space services.
The approach is not transparent for later addition of system memory ranges
to the GCD memory space map. (Such ranges should be encrypted.) OVMF does
not do such a thing at the moment, so this approach should be OK.
The driver is being added to the APRIORI DXE file so that, we clear the
C-bit from MMIO regions before any driver accesses it.
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Leo Duran <leo.duran@amd.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Suggested-by: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Jordan Justen <jordan.l.justen@intel.com>
Laszlo Ersek
Brijesh Singh