Re: [Qemu-stable] [PATCH for-2.12] cpus.c: ensure running CPU recalculates icount deadlines on timer expiry

[Richard Henderson]

On 04/06/2018 10:38 PM, Peter Maydell wrote:
> When we run in TCG icount mode, we calculate the number of instructions
> to execute using tcg_get_icount_limit(), which ensures that we stop
> execution at the next timer deadline. However there is a bug where
> currently we do not recalculate that limit if the guest reprograms
> a timer so that the next deadline moves closer, and so we will
> continue execution until the original limit and fire the timer
> later than we should.
> 
> Fix this bug in qemu_timer_notify_cb(): if we are currently running
> a VCPU in icount mode, we simply need to kick it out of the main
> loop and back to tcg_cpu_exec(), where it will recalculate the
> icount limit. If we are not currently running a VCPU, then we
> retain the existing logic for waking up a halted CPU.
> 
> Cc: address@hidden
> Fixes: https://bugs.launchpad.net/qemu/+bug/1754038
> Signed-off-by: Peter Maydell <address@hidden>
> ---
> Thanks to Paolo for tracking down which function needed fixing!

Seconded.

Reviewed-by: Richard Henderson <address@hidden>


r~