Re: [PATCH 3/6] MdePkg/UefiLib: introduce EfiAllocatePeiAccessiblePages routine

["Zeng, Star" <star.zeng@intel.com>]

On 2018/5/22 22:08, Ard Biesheuvel wrote:
> Add a routine to UefiLib that abstracts the allocation of memory that
> should be accessible by PEI after a warm reboot. We will use it to

Glad to see this patch series.

It is the case "PEI for S3", but not "PEI after a warm reboot".


Thanks,
Star

> replace open coded implementations that limit the address to < 4 GB,
> which may not be possible on non-Intel systems that have no 32-bit
> addressable memory at all.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>   MdePkg/Include/Library/UefiLib.h | 23 ++++++++++
>   MdePkg/Library/UefiLib/UefiLib.c | 48 ++++++++++++++++++++
>   2 files changed, 71 insertions(+)
> 
> diff --git a/MdePkg/Include/Library/UefiLib.h b/MdePkg/Include/Library/UefiLib.h
> index 256498e3fd8d..8fa077af41e0 100644
> --- a/MdePkg/Include/Library/UefiLib.h
> +++ b/MdePkg/Include/Library/UefiLib.h
> @@ -1520,4 +1520,27 @@ EfiLocateProtocolBuffer (
>     OUT UINTN     *NoProtocols,
>     OUT VOID      ***Buffer
>     );
> +
> +/**
> +  Allocates one or more 4KB pages of a given type from a memory region that is
> +  accessible to PEI.
> +
> +  Allocates the number of 4KB pages of type 'MemoryType' and returns a
> +  pointer to the allocated buffer.  The buffer returned is aligned on a 4KB
> +  boundary.  If Pages is 0, then NULL is returned.  If there is not enough
> +  memory remaining to satisfy the request, then NULL is returned.
> +
> +  @param[in]  MemoryType            The memory type to allocate
> +  @param[in]  Pages                 The number of 4 KB pages to allocate.
> +
> +  @return A pointer to the allocated buffer or NULL if allocation fails.
> +
> +**/
> +VOID *
> +EFIAPI
> +EfiAllocatePeiAccessiblePages (
> +  IN EFI_MEMORY_TYPE  MemoryType,
> +  IN UINTN            Pages
> +  );
> +
>   #endif
> diff --git a/MdePkg/Library/UefiLib/UefiLib.c b/MdePkg/Library/UefiLib/UefiLib.c
> index ba449a1c34ce..3a9d75149dd7 100644
> --- a/MdePkg/Library/UefiLib/UefiLib.c
> +++ b/MdePkg/Library/UefiLib/UefiLib.c
> @@ -1715,3 +1715,51 @@ EfiLocateProtocolBuffer (
>   
>     return EFI_SUCCESS;
>   }
> +
> +/**
> +  Allocates one or more 4KB pages of a given type from a memory region that is
> +  accessible to PEI.
> +
> +  Allocates the number of 4KB pages of type 'MemoryType' and returns a
> +  pointer to the allocated buffer.  The buffer returned is aligned on a 4KB
> +  boundary.  If Pages is 0, then NULL is returned.  If there is not enough
> +  memory remaining to satisfy the request, then NULL is returned.
> +
> +  @param[in]  MemoryType            The memory type to allocate
> +  @param[in]  Pages                 The number of 4 KB pages to allocate.
> +
> +  @return A pointer to the allocated buffer or NULL if allocation fails.
> +
> +**/
> +VOID *
> +EFIAPI
> +EfiAllocatePeiAccessiblePages (
> +  IN EFI_MEMORY_TYPE  MemoryType,
> +  IN UINTN            Pages
> +  )
> +{
> +  EFI_STATUS            Status;
> +  EFI_PHYSICAL_ADDRESS  Memory;
> +  EFI_ALLOCATE_TYPE     AllocType;
> +
> +  if (Pages == 0) {
> +    return NULL;
> +  }
> +
> +#ifdef MDE_CPU_X64
> +  //
> +  // On X64 systems, a X64 build of DXE may be combined with a 32-bit build of
> +  // PEI, and so we need to allocate below 4 GB to ensure that the allocation
> +  // is accessible by PEI.
> +  //
> +  AllocType = AllocateMaxAddress;
> +  Memory = MAX_UINT32;
> +#else
> +  AllocType = AllocateAnyPages;
> +#endif
> +  Status = gBS->AllocatePages (AllocType, MemoryType, Pages, &Memory);
> +  if (EFI_ERROR (Status)) {
> +    return NULL;
> +  }
> +  return (VOID *)(UINTN)Memory;
> +}
>