Re: [PATCH 2/2] OvmfPkg/ResetVector: Exclude SEV launch secrets page from pre-validation

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

On 30/03/2022 8:20, Gerd Hoffmann wrote:
>   Hi,
> 
>> Check if that page is defined; if it is, skip it in the metadata list.
>> In such case, VMM should fill the page with the hashes content, or
>> explicitly update it as a zero page (if kernel hashes are not used).
> 
> Is it an option to just skip the page unconditionally?
> 
> I think in the OvmfPkgX64 build the page is not used, so it probably
> doesn't matter whenever it is included or not, and it would make things
> a bit less confusing ...
> 


Brijesh,

What would happen if we change this:

    %define SNP_SEC_MEM_BASE_DESC_3 (CPUID_BASE + CPUID_SIZE)

to:

    %define SNP_SEC_MEM_BASE_DESC_3 (FixedPcdGet32 (PcdOvmfSecPeiTempRamBase))

in OvmfPkg/ResetVector/ResetVector.nasmb ?

It means that the page starting at MEMFD_BASE_ADDRESS+0x00F000 (that is, the page
that follows the SNP CPUID page) will not be pre-validated by QEMU.

I'm not sure what are the implications.


-Dov