[edk2-devel] [PATCH v2 08/11] OvmfPkg/AmdSev/SecretPei: build hob for full page

[Lendacky, Thomas via groups.io]

On 7/6/21 3:54 AM, Dov Murik wrote:
> Round up the size of the SEV launch secret area to a whole page, as
> required by BuildMemoryAllocationHob.  This will allow the secret
> area defined in the MEMFD to take less than a whole 4KB page.
> 
> Cc: Laszlo Ersek <lersek at redhat.com>
> Cc: Ard Biesheuvel <ardb+tianocore at kernel.org>
> Cc: Jordan Justen <jordan.l.justen at intel.com>
> Cc: Ashish Kalra <ashish.kalra at amd.com>
> Cc: Brijesh Singh <brijesh.singh at amd.com>
> Cc: Erdem Aktas <erdemaktas at google.com>
> Cc: James Bottomley <jejb at linux.ibm.com>
> Cc: Jiewen Yao <jiewen.yao at intel.com>
> Cc: Min Xu <min.m.xu at intel.com>
> Cc: Tom Lendacky <thomas.lendacky at amd.com>
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3457
> Signed-off-by: Dov Murik <dovmurik at linux.ibm.com>
> ---
>  OvmfPkg/AmdSev/SecretPei/SecretPei.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/OvmfPkg/AmdSev/SecretPei/SecretPei.c b/OvmfPkg/AmdSev/SecretPei/SecretPei.c
> index ad491515dd5d..db4267428e5a 100644
> --- a/OvmfPkg/AmdSev/SecretPei/SecretPei.c
> +++ b/OvmfPkg/AmdSev/SecretPei/SecretPei.c
> @@ -15,9 +15,16 @@ InitializeSecretPei (
>    IN CONST EFI_PEI_SERVICES     **PeiServices
>    )
>  {
> +  UINT64 RoundedSize;
> +
> +  RoundedSize = PcdGet32 (PcdSevLaunchSecretSize);

Can you just unconditionally perform:

  RoundedSize = ALIGN_VALUE (RoundedSize, EFI_PAGE_SIZE);

Or use ALIGN_VALUE () in the if statement if you don't want to do it
unconditionally?

Or even use ALIGN_VALUE on size value in the BuildMemoryAllocationHob()
call below.

Thanks,
Tom

> +  if (RoundedSize % EFI_PAGE_SIZE != 0) {
> +    RoundedSize = (RoundedSize / EFI_PAGE_SIZE + 1) * EFI_PAGE_SIZE;
> +  }
> +
>    BuildMemoryAllocationHob (
>      PcdGet32 (PcdSevLaunchSecretBase),
> -    PcdGet32 (PcdSevLaunchSecretSize),
> +    RoundedSize,
>      EfiBootServicesData
>      );
>  
> 


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