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

["Dov Murik" <dovmurik@linux.ibm.com>]

On 19/07/2021 19:19, Tom Lendacky wrote:
> 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@redhat.com>
>> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
>> Cc: Jordan Justen <jordan.l.justen@intel.com>
>> Cc: Ashish Kalra <ashish.kalra@amd.com>
>> Cc: Brijesh Singh <brijesh.singh@amd.com>
>> Cc: Erdem Aktas <erdemaktas@google.com>
>> Cc: James Bottomley <jejb@linux.ibm.com>
>> Cc: Jiewen Yao <jiewen.yao@intel.com>
>> Cc: Min Xu <min.m.xu@intel.com>
>> Cc: Tom Lendacky <thomas.lendacky@amd.com>
>> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3457
>> Signed-off-by: Dov Murik <dovmurik@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.

Yes, that's much better.  Thanks for introducing me to this macro.

-Dov


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