Re: [PATCH v1 01/21] accel/tcg: Change interrupt/exception handling to remove implied BQL

[Robert Foley]

On Sat, 8 Aug 2020 at 08:00, Paolo Bonzini <pbonzini@redhat.com> wrote:
> > We are thinking that 2) would be a good option.
>
> Yes, it is.  The only slight complication is that you'd have both
> ->do_interrupt and ->do_interrupt_locked so you probably should add some
> consistency check, for example
>
>     /*
>      * cc->do_interrupt_locked should only be needed if
>      * the class uses cpu_common_do_interrupt.
>      */
>     assert(cc->do_interrupt == cpu_common_do_interrupt ||
>            !cc->do_interrupt_locked);
>
> Therefore, a variant is to add ->do_interrupt_locked to ARMCPUClass and
> CRISCPUClass (target/avr/helper.c can just call
> avr_cpu_do_interrupt_locked, because that's the only value that
> cc->do_interrupt can have).  Then ARM and CRIS can have a do_interrupt
> like you wrote above:
>
> void arm_do_interrupt(CPUState *cs)
> {
>     ARMCPUClass *acc = ARM_CPU_GET_CLASS(cs);
>     qemu_mutex_lock_iothread();
>     acc->do_interrupt_locked(cpu);
>     qemu_mutex_unlock_iothread();
> }
>
> with a small duplication between ARM and CRIS but on the other hand a
> simpler definition of the common CPUClass.


Thanks for all the details! It sounds like a good approach and we will
move forward with it.

Thanks & Regards,
-Rob

>
> Paolo
>