Re: [PATCH v6 1/2] MdeModulePkg/DxeCore: Filter out all paging capabilities

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 16 November 2017 at 07:26, Jian J Wang <jian.j.wang@intel.com> wrote:
> Some OSs will treat EFI_MEMORY_DESCRIPTOR.Attribute as really
> set attributes and change memory paging attribute accordingly.
> But current EFI_MEMORY_DESCRIPTOR.Attribute is assigned by
> value from Capabilities in GCD memory map. This might cause
> boot problems. Clearing all paging related capabilities can
> workaround it. The code added in this patch is supposed to
> be removed once the usage of EFI_MEMORY_DESCRIPTOR.Attribute
> is clarified in UEFI spec and adopted by both EDK-II Core and
> all supported OSs.
>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Star Zeng <star.zeng@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
> ---
>  MdeModulePkg/Core/Dxe/Mem/Page.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
>
> diff --git a/MdeModulePkg/Core/Dxe/Mem/Page.c b/MdeModulePkg/Core/Dxe/Mem/Page.c
> index c9219cc068..783b576e35 100644
> --- a/MdeModulePkg/Core/Dxe/Mem/Page.c
> +++ b/MdeModulePkg/Core/Dxe/Mem/Page.c
> @@ -1829,6 +1829,23 @@ CoreGetMemoryMap (
>    //
>    BufferSize = ((UINT8 *)MemoryMap - (UINT8 *)MemoryMapStart);
>
> +  //
> +  // WORKAROUND: Some OSs will treat EFI_MEMORY_DESCRIPTOR.Attribute as really
> +  //             set attributes and change memory paging attribute accordingly.
> +  //             But current EFI_MEMORY_DESCRIPTOR.Attribute is assigned by
> +  //             value from Capabilities in GCD memory map. This might cause
> +  //             boot problems. Clearing all paging related capabilities can
> +  //             workaround it. Following code is supposed to be removed once
> +  //             the usage of EFI_MEMORY_DESCRIPTOR.Attribute is clarified in
> +  //             UEFI spec and adopted by both EDK-II Core and all supported
> +  //             OSs.
> +  //
> +  while (MemoryMapStart < MemoryMap) {
> +    MemoryMapStart->Attribute &= ~(UINT64)(EFI_MEMORY_RP | EFI_MEMORY_RO |
> +                                           EFI_MEMORY_XP);

Why is EFI_MEMORY_WP missing here?

> +    MemoryMapStart = NEXT_MEMORY_DESCRIPTOR(MemoryMapStart, Size);
> +  }
> +
>    Status = EFI_SUCCESS;
>
>  Done:
> --
> 2.14.1.windows.1
>