On Fri, Aug 2, 2024 at 10:41 PM Michael Roth <michael.roth@xxxxxxx> wrote: > On Fri, Aug 02, 2024 at 01:53:33AM +0200, Paolo Bonzini wrote: > > Even though KVM_SEV_GET_ATTESTATION_REPORT is not one of the commands > > that were added for SEV-SNP guests, it can be applied to them. Filtering > > Is the command actually succeeding for an SNP-enabled guest? When I > test this, I get a fw_err code of 1 (INVALID_PLATFORM_STATE), and > after speaking with some firmware folks that seems to be the expected > behavior. So is there no equivalent of QEMU's query-sev-attestation-report for SEV-SNP? (And is there any user of query-sev-attestation-report for non-SNP?) Paolo > There's also some other things that aren't going to work as expected, > e.g. KVM uses sev->handle as the handle for the guest it wants to fetch > the attestation report for, but in the case of SNP, sev->handle will be > uninitialized since that only happens via KVM_SEV_LAUNCH_UPDATE_DATA, > which isn't usable for SNP guests. > > As I understand it, the only firmware commands allowed for SNP guests are > those listed in the SNP firmware ABI, section "Command Reference", and > in any instance where a legacy command from the legacy SEV/SEV-ES firmware > ABI is also applicable for SNP, the legacy command will be defined again > in the "Command Reference" section of the SNP spec. E.g., GET_ID is > specifically documented in both the SEV/SEV-ES firmware ABI, as well as > the SNP firmware ABI spec. But ATTESTATION (and the similar LAUNCH_MEASURE) > are only mentioned in the SEV/SEV-ES Firmware ABI, so I think it makes > sense that KVM also only allows them for SEV/SEV-ES.
