Re: [PATCH Part2 v5 23/45] KVM: SVM: Add KVM_SNP_INIT command

[Ashish Kalra]

Hello Alper,

On 6/13/22 20:58, Alper Gun wrote:
> static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
> >   {
> > +       bool es_active = (argp->id == KVM_SEV_ES_INIT || argp->id == KVM_SEV_SNP_INIT);
> >          struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> > -       bool es_active = argp->id == KVM_SEV_ES_INIT;
> > +       bool snp_active = argp->id == KVM_SEV_SNP_INIT;
> >          int asid, ret;
> >
> >          if (kvm->created_vcpus)
> > @@ -249,12 +269,22 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
> >                  return ret;
> >
> >          sev->es_active = es_active;
> > +       sev->snp_active = snp_active;
> >          asid = sev_asid_new(sev);
> >          if (asid < 0)
> >                  goto e_no_asid;
> >          sev->asid = asid;
> >
> > -       ret = sev_platform_init(&argp->error);
> > +       if (snp_active) {
> > +               ret = verify_snp_init_flags(kvm, argp);
> > +               if (ret)
> > +                       goto e_free;
> > +
> > +               ret = sev_snp_init(&argp->error);
> > +       } else {
> > +               ret = sev_platform_init(&argp->error);
> After SEV INIT_EX support patches, SEV may be initialized in the platform late.
> In my tests, if SEV has not been initialized in the platform yet, SNP
> VMs fail with SEV_DF_FLUSH required error. I tried calling
> SEV_DF_FLUSH right after the SNP platform init but this time it failed
> later on the SNP launch update command with SEV_RET_INVALID_PARAM
> error. Looks like there is another dependency on SEV platform
> initialization.
>
> Calling sev_platform_init for SNP VMs fixes the problem in our tests.

Trying to get some more context for this issue.

When you say after SEV_INIT_EX support patches, SEV may be initialized 
in the platform late, do you mean sev_pci_init()->sev_snp_init() ... 
sev_platform_init() code path has still not executed on the host BSP ?

Before launching the first SNP/SEV guest launch after INIT, we need to 
issue SEV_CMD_DF_FLUSH command.

I assume that we will always be initially doing SNP firmware 
initialization with SNP_INIT command followed by sev_platform_init(), if 
SNP is enabled on boot CPU.

Thanks, Ashish