Re: [PATCH v2 3/4] s390x/pv: Introduce a s390_pv_check() helper for runtime

[Cédric Le Goater]

On 1/9/23 10:04, Janosch Frank wrote:
> On 1/6/23 08:53, Cédric Le Goater wrote:
> > From: Cédric Le Goater <clg@redhat.com>
> >
> > If a secure kernel is started in a non-protected VM, the OS will hang
> > during boot without giving a proper error message to the user.
>
> Most of the time you see nothing in the console because libvirt is too slow. If 
> you start the VM in paused mode, attach a console and then resume it, then 
> you'll see a nice error message.

If you wait long enough, the VM fails to mount / and falls into the dracut
initrams.

> > Perform the checks on Confidential Guest support at runtime with an
> > helper called from the service call switching the guest to protected
> > mode.
>
> If we don't have PV support then the subcodes >=8 are a specification exception 
> so this is never executed AFAIK.

It is. The test on huge page size was added just above this change.

Thanks,

C.

> >       if (env->psw.mask & PSW_MASK_PSTATE) {
> >           s390_program_interrupt(env, PGM_PRIVILEGED, ra);
> > @@ -176,6 +177,12 @@ out:
> >               return;
> >           }
> > +        if (!s390_pv_check(&local_err)) {
> > +            error_report_err(local_err);
> > +            env->regs[r1 + 1] = DIAG_308_RC_INVAL_FOR_PV;
> > +            return;
> > +        }
> > +
> >           s390_ipl_reset_request(cs, S390_RESET_PV);
> >           break;
> >       default: