Re: [edk2-devel] [PATCH RFC v2 07/28] OvmfPkg: Use MemEncryptSevClearMmioPageEncMask() to clear EncMask from Mmio

["Laszlo Ersek" <lersek@redhat.com>]

On 04/30/21 13:51, Brijesh Singh wrote:
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275
> 
> Use the MemEncryptSevClearMmioPageEncMask() to clear memory encryption mask
> for the Mmio address range from the current page table context.
> 
> Cc: James Bottomley <jejb@linux.ibm.com>
> Cc: Min Xu <min.m.xu@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Tom Lendacky <thomas.lendacky@amd.com>
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Erdem Aktas <erdemaktas@google.com>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
>  OvmfPkg/AmdSevDxe/AmdSevDxe.c                              | 10 ++++------
>  OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FwBlockServiceDxe.c |  5 ++---
>  OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlashSmm.c      |  5 ++---
>  3 files changed, 8 insertions(+), 12 deletions(-)
> 
> diff --git a/OvmfPkg/AmdSevDxe/AmdSevDxe.c b/OvmfPkg/AmdSevDxe/AmdSevDxe.c
> index 689bfb376d..80831b81fa 100644
> --- a/OvmfPkg/AmdSevDxe/AmdSevDxe.c
> +++ b/OvmfPkg/AmdSevDxe/AmdSevDxe.c
> @@ -53,11 +53,10 @@ AmdSevDxeEntryPoint (
>        Desc = &AllDescMap[Index];
>        if (Desc->GcdMemoryType == EfiGcdMemoryTypeMemoryMappedIo ||
>            Desc->GcdMemoryType == EfiGcdMemoryTypeNonExistent) {
> -        Status = MemEncryptSevClearPageEncMask (
> +        Status = MemEncryptSevClearMmioPageEncMask (
>                     0,
>                     Desc->BaseAddress,
> -                   EFI_SIZE_TO_PAGES (Desc->Length),
> -                   FALSE
> +                   EFI_SIZE_TO_PAGES (Desc->Length)
>                     );
>          ASSERT_EFI_ERROR (Status);
>        }
> @@ -73,11 +72,10 @@ AmdSevDxeEntryPoint (
>    // the range.
>    //
>    if (PcdGet16 (PcdOvmfHostBridgePciDevId) == INTEL_Q35_MCH_DEVICE_ID) {
> -    Status = MemEncryptSevClearPageEncMask (
> +    Status = MemEncryptSevClearMmioPageEncMask (
>                 0,
>                 FixedPcdGet64 (PcdPciExpressBaseAddress),
> -               EFI_SIZE_TO_PAGES (SIZE_256MB),
> -               FALSE
> +               EFI_SIZE_TO_PAGES (SIZE_256MB)
>                 );
>  
>      ASSERT_EFI_ERROR (Status);
> diff --git a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FwBlockServiceDxe.c b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FwBlockServiceDxe.c
> index 1f285e0083..ab40087a84 100644
> --- a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FwBlockServiceDxe.c
> +++ b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FwBlockServiceDxe.c
> @@ -205,11 +205,10 @@ MarkIoMemoryRangeForRuntimeAccess (
>    // memory range.
>    //
>    if (MemEncryptSevIsEnabled ()) {
> -    Status = MemEncryptSevClearPageEncMask (
> +    Status = MemEncryptSevClearMmioPageEncMask (
>                 0,
>                 BaseAddress,
> -               EFI_SIZE_TO_PAGES (Length),
> -               FALSE
> +               EFI_SIZE_TO_PAGES (Length)
>                 );
>      ASSERT_EFI_ERROR (Status);
>    }
> diff --git a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlashSmm.c b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlashSmm.c
> index 7eb80bfeff..ea75b489c7 100644
> --- a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlashSmm.c
> +++ b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlashSmm.c
> @@ -38,11 +38,10 @@ QemuFlashBeforeProbe (
>    // C-bit on flash ranges from SMM page table.
>    //
>  
> -  Status = MemEncryptSevClearPageEncMask (
> +  Status = MemEncryptSevClearMmioPageEncMask (
>               0,
>               BaseAddress,
> -             EFI_SIZE_TO_PAGES (FdBlockSize * FdBlockCount),
> -             FALSE
> +             EFI_SIZE_TO_PAGES (FdBlockSize * FdBlockCount)
>               );
>    ASSERT_EFI_ERROR (Status);
>  }
> 

The contents of this patch are sound, but they are incomplete, and
incorrectly structured too.

(1) Please provide a separate patch for each modified module.

(2) You missed the MemEncryptSevClearPageEncMask() call in
TpmMmioSevDecryptPeimEntryPoint()
[OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPeim.c] -- probably
because you worked on this series in parallel with Tom working on the
SEV-ES TPM fixes.

In the end, this patch should be split into three patches (because the
change is needed for three modules).

Thanks
Laszlo