Re: [Qemu-devel] [PATCH v1 3/3] tcg-runtime: short-circuit lookup_tb_ptr on IRQs

[Richard Henderson]

On 06/14/2017 12:11 PM, Peter Maydell wrote:
> On 14 June 2017 at 18:49, Alex Bennée <address@hidden> wrote:
> > diff --git a/target/arm/op_helper.c b/target/arm/op_helper.c
> > index 2a85666579..7e67bb3db2 100644
> > --- a/target/arm/op_helper.c
> > +++ b/target/arm/op_helper.c
> > @@ -835,6 +835,9 @@ void HELPER(msr_i_pstate)(CPUARMState *env, uint32_t op, 
> > uint32_t imm)
> >           break;
> >       case 0x1f: /* DAIFClear */
> >           env->daif &= ~((imm << 6) & PSTATE_DAIF);
> > +        /* This may result in pending IRQs being unmasked so ensure we
> > +           exit the loop */
> > +        cpu_exit(ENV_GET_CPU(env));
> >           break;
> >       default:
> >           g_assert_not_reached();
>
> The 'op' field we're switching on here is just a constant
> from the instruction encoding, so I'd rather see us
> identify that in translate-a64.c and end the TB or
> whatever when we need to, rather than doing the
> longjump-out-of-here that cpu_exit() does at runtime.

cpu_exit isn't the longjmp; this is just a set of exit_request and icount_decr.

That said, you're right that we can do this more directly from the translator.


r~