Re: [PATCH v6 00/29] Add AMD Secure Nested Paging (SEV-SNP) support

["Brijesh Singh" <brijesh.singh@amd.com>]

On 9/9/21 6:22 AM, Gerd Hoffmann wrote:
>   Hi,
>
>> I am not sure if its a good idea to pack a header like above in a 32-bit
>> PCD. The caller need to unpack the 32-bit number and perform a bitshit
>> etc. Additionally we also need to check for reserved bits being set to
>> zero etc. I am more inclined toward something like this:
>>
>> enum {
> Well, various places probably just need to know whenever they should
> call into the sev or the tdx library, so grouping stuff makes sense to
> me.  We don't need bitfields for that though, could also be done this
> way:
>
> enum {
>    NOT_ENCRYPTED = 0,
>    AMD_SEV = 0x100,
>    AMD_SEV_ES,
>    [ ... ]
>    INTEL_TDX = 0x200,
>    [ ... ]
> }
>
> So if you need the exact mode you can compare values as-is, if you want
> figure which vendor library should be called you'll just mask out the
> least significant 8 bits.

Yes, this also works fine.

thanks