On 02.07.2025 16:41, Andrew Cooper wrote:
> @@ -461,12 +468,19 @@ void mwait_idle_with_hints(unsigned int eax, unsigned
> int ecx)
>
> monitor(this_softirq_pending, 0, 0);
>
> + ASSERT(!local_irq_is_enabled());
> +
> if ( !*this_softirq_pending )
> {
> struct cpu_info *info = get_cpu_info();
>
> spec_ctrl_enter_idle(info);
> - mwait(eax, ecx);
> +
> + if ( ecx & MWAIT_ECX_INTERRUPT_BREAK )
> + mwait(eax, ecx);
> + else
> + sti_mwait_cli(eax, ecx);
Actually, I'm curious: It seems quite likely that you did consider an
alternative resulting in assembly code like this:
test $MWAIT_ECX_INTERRUPT_BREAK, %cl
jz 0f
sti
0:
monitor
cli
CLI being a relatively cheap operation aiui, is there anything wrong or
undesirable with this (smaller overall) alternative?
Jan
