Re: [PATCH v2] target/i386: Add unaccepted memory configuration

[Tom Lendacky]

On 6/30/22 03:14, Daniel P. Berrangé wrote:
> On Wed, Jun 29, 2022 at 07:37:01PM +0000, Dionna Glaze wrote:
> > For SEV-SNP, an OS is "SEV-SNP capable" without supporting this UEFI
> > v2.9 memory type. In order for OVMF to be able to avoid pre-validating
> > potentially hundreds of gibibytes of data before booting, it needs to
> > know if the guest OS can support its use of the new type of memory in
> > the memory map.
>
> This talks about something supported for SEV-SNP, but....
>
> >   static void
> >   sev_guest_class_init(ObjectClass *oc, void *data)
> >   {
> > @@ -376,6 +401,14 @@ sev_guest_class_init(ObjectClass *oc, void *data)
> >                                      sev_guest_set_kernel_hashes);
> >       object_class_property_set_description(oc, "kernel-hashes",
> >               "add kernel hashes to guest firmware for measured Linux boot");
> > +    object_class_property_add_enum(oc, "accept-all-memory",
> > +                                   "MemoryAcceptance",
> > +                                   &memory_acceptance_lookup,
> > +        sev_guest_get_accept_all_memory, sev_guest_set_accept_all_memory);
> > +    object_class_property_set_description(
> > +        oc, "accept-all-memory",
> > +        "false: Accept all memory, true: Accept up to 4G and leave the rest 
> > unaccepted (UEFI"
> > +        " v2.9 memory type), default: default firmware behavior.");
> >   }
>
> ..this is adding a property to the 'sev-guest' object, which only
> targets SEV/SEV-ES currently AFAIK.
>
> The most recent patches I recall for SEV-SNP introduced a new
> 'sev-snp-guest' object instead of overloading the existing
> 'sev-guest' object:
>
>    https://lists.gnu.org/archive/html/qemu-devel/2021-08/msg04757.html

Correct, the SNP support for Qemu is only RFC at this point until the KVM 
support for SNP is (near) finalized.

Thanks,
Tom

> With regards,
> Daniel