> From: Paolo Bonzini [mailto:pbonz...@redhat.com] > On 28/08/2018 09:23, Pavel Dovgalyuk wrote: > > Hi, Paolo! > > > > Seems that this one breaks the record/replay. > > What are the symptoms?
Please look below. > >> From: Paolo Bonzini [mailto:pbonz...@redhat.com] > >> In the next patch, we will need to write cpu_ticks_offset from any > >> thread, even outside the BQL. Currently, it is protected by the BQL > >> just because cpu_enable_ticks and cpu_disable_ticks happen to hold it, > >> but the critical sections are well delimited and it's easy to remove > >> the BQL dependency. > >> > >> Add a spinlock that matches vm_clock_seqlock, and hold it when writing > >> to the TimerState. This also lets us fix cpu_update_icount when 64-bit > >> atomics are not available. > >> > >> Fields of TiemrState are reordered to avoid padding. > >> > >> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> > >> --- > >> cpus.c | 72 ++++++++++++++++++++++++++++++++++++++-------------------- > >> 1 file changed, 47 insertions(+), 25 deletions(-) > >> Here is the description: > >> static void icount_adjust_rt(void *opaque) > >> @@ -480,7 +494,8 @@ static void icount_warp_rt(void) > >> return; > >> } > >> > >> - seqlock_write_begin(&timers_state.vm_clock_seqlock); > >> + seqlock_write_lock(&timers_state.vm_clock_seqlock, > >> + &timers_state.vm_clock_lock); > > > > After locking here, > > > >> if (runstate_is_running()) { > >> int64_t clock = REPLAY_CLOCK(REPLAY_CLOCK_VIRTUAL_RT, > >> cpu_get_clock_locked()); > > > > REPLAY_CLOCK can't request icount with cpu_get_icount_raw, because > > it loops infinitely here: > > > > do { > > start = seqlock_read_begin(&timers_state.vm_clock_seqlock); > > icount = cpu_get_icount_raw_locked(); > > } while (seqlock_read_retry(&timers_state.vm_clock_seqlock, start)); > > > > Pavel Dovgalyuk
