Re: [PATCH v6 07/11] hvf: Add Apple Silicon support

[Peter Maydell]

On Wed, 10 Feb 2021 at 22:21, Alexander Graf <agraf@csgraf.de> wrote:
>
>
> On 28.01.21 16:52, Peter Maydell wrote:
> > On Wed, 20 Jan 2021 at 22:44, Alexander Graf <agraf@csgraf.de> wrote:
> >> +            break;
> >> +        case EC_AA64_SMC:
> >> +            cpu_synchronize_state(cpu);
> >> +            if (arm_is_psci_call(arm_cpu, EXCP_SMC)) {
> >> +                arm_handle_psci_call(arm_cpu);
> > Have you checked that all the PSCI code really can cope
> > with being called from a non-TCG accelerator? (As an example
> > the CPU_SUSPEND implementation calls the TCG wfi helper...)
>
>
> I have not explicitly tried it, but I don't see why the TCG
> implementation of wfi should in principle break with hvf.

Because the TCG implementation of wfi is "set some state fields
and then longjump out to the TCG exec_cpu code-execution loop",
and hvf doesn't use that loop.

> >> +            } else {
> >> +                DPRINTF("unknown SMC! %016llx", env->xregs[0]);
> >> +                env->xregs[0] = -1;
> > This should inject an UNDEF exception into the guest. (Compare
> > the pre_smc helper in target/arm/op_helper.c for TCG.)
>
>
> That would break Windows, which is one of the main use cases for hvf
> support in QEMU.

Why is Windows making bogus SMC calls ?

thanks
-- PMM