Re: [Qemu-arm] [PATCH] target/aarch64: exit to main loop after handling MSR

[Paolo Bonzini]

On 14/06/2017 14:14, Alex Bennée wrote:
>> Then Emilio's patch, if a bit of a heavy hammer, is correct. After
>> aa64_daif_write needs you need an exit_tb so that arm_cpu_exec_interrupt
>> is executed again.
> 
> This is a case of cpu->interrupt_request being pending but not having
> set cpu->icount_decr yet to signal the exit.

Rather than "yet", "anymore".  So far it has always been an invariant
that anything that re-enabled an interrupt had to do exit_tb.

> Wouldn't another approach
> (that didn't involve futzing with each front-end) to be to check
> cpu->interrupt_request and force the exit in lookup_tb_ptr?

That would cause an unnecessary slowdown in code that runs with
interrupts disabled but does a lot of indirect jumps...  ppc's SLOF
firmware probably qualifies.

Paolo