Re: [RFC v18 08/15] i386: split smm helper (softmmu)

[Paolo Bonzini]

On 15/02/21 15:05, Claudio Fontana wrote:
> On 2/15/21 2:30 PM, Paolo Bonzini wrote:
> > On 15/02/21 13:59, Claudio Fontana wrote:
> > > Yes. The difference between before the patch and after the patch 
> > > is that before we were still going through all the code in
> > > tcg_gen_callN, via the call to gen_helper_rsm macro, only to call
> > > finally an empty function for CONFIG_USER_ONLY (helper_rsm()
> > > {}),
> > >
> > > while now we do not generate anything, we do not call the
> > > gen_helper_rsm macro at all, so we don't go through
> > > tcg_gen_callN.
> >
> > Can we even have an abort() for such cases?
> >
> > Paolo
>
> Hi Paolo,
>
> where are you suggesting to have an abort()?
>
> You mean that we should abort() QEMU as soon as we detect in
> translate.c an RSM instruction in user-mode?

Translating it is okay (it's just a guaranteed SIGILL), but I'm thinking
of aborting if s->flags & HF_SMM_MASK is true.  Likewise if we see
CPU_INTERRUPT_SMI.

Paolo

>     case 0x1aa: /* rsm */
>         gen_svm_check_intercept(s, pc_start, SVM_EXIT_RSM);
>         if (!(s->flags & HF_SMM_MASK))
>             goto illegal_op;
>         gen_update_cc_op(s);
>         gen_jmp_im(s, s->pc - s->cs_base);
> #ifndef CONFIG_USER_ONLY
>         gen_helper_rsm(cpu_env);
> #endif /* CONFIG_USER_ONLY */
>         gen_eob(s);
>         break;