On 14/11/2017 09:17, Pavel Dovgalyuk wrote:
> This patch adds saving and restoring of the icount warp
> timers in the vmstate.
> It is needed because there timers affect the virtual clock value.
> Therefore determinism of the execution in icount record/replay mode
> depends on determinism of the timers.
>
> Signed-off-by: Pavel Dovgalyuk <pavel.dovga...@ispras.ru>
>
> ---
> cpus.c | 85
> ++++++++++++++++++++++++++++++++++++++++++++++++++--------------
> 1 file changed, 66 insertions(+), 19 deletions(-)
>
> diff --git a/cpus.c b/cpus.c
> index c728f3a..7a3abea 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -119,16 +119,11 @@ static bool all_cpu_threads_idle(void)
> /* Protected by TimersState seqlock */
>
> static bool icount_sleep = true;
> -static int64_t vm_clock_warp_start = -1;
> /* Conversion factor from emulated instructions to virtual clock ticks. */
> static int icount_time_shift;
> /* Arbitrarily pick 1MIPS as the minimum allowable speed. */
> #define MAX_ICOUNT_SHIFT 10
>
> -static QEMUTimer *icount_rt_timer;
> -static QEMUTimer *icount_vm_timer;
> -static QEMUTimer *icount_warp_timer;
> -
> typedef struct TimersState {
> /* Protected by BQL. */
> int64_t cpu_ticks_prev;
> @@ -146,6 +141,11 @@ typedef struct TimersState {
> int64_t qemu_icount_bias;
> /* Only written by TCG thread */
> int64_t qemu_icount;
> + /* for adjusting icount */
> + int64_t vm_clock_warp_start;
> + QEMUTimer *icount_rt_timer;
> + QEMUTimer *icount_vm_timer;
> + QEMUTimer *icount_warp_timer;
> } TimersState;
>
> static TimersState timers_state;
> @@ -431,14 +431,14 @@ static void icount_adjust(void)
>
> static void icount_adjust_rt(void *opaque)
> {
> - timer_mod(icount_rt_timer,
> + timer_mod(timers_state.icount_rt_timer,
> qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL_RT) + 1000);
> icount_adjust();
> }
>
> static void icount_adjust_vm(void *opaque)
> {
> - timer_mod(icount_vm_timer,
> + timer_mod(timers_state.icount_vm_timer,
> qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
> NANOSECONDS_PER_SECOND / 10);
> icount_adjust();
> @@ -459,7 +459,7 @@ static void icount_warp_rt(void)
> */
> do {
> seq = seqlock_read_begin(&timers_state.vm_clock_seqlock);
> - warp_start = vm_clock_warp_start;
> + warp_start = timers_state.vm_clock_warp_start;
> } while (seqlock_read_retry(&timers_state.vm_clock_seqlock, seq));
>
> if (warp_start == -1) {
> @@ -472,7 +472,7 @@ static void icount_warp_rt(void)
> cpu_get_clock_locked());
> int64_t warp_delta;
>
> - warp_delta = clock - vm_clock_warp_start;
> + warp_delta = clock - timers_state.vm_clock_warp_start;
> if (use_icount == 2) {
> /*
> * In adaptive mode, do not let QEMU_CLOCK_VIRTUAL run too
> @@ -484,7 +484,7 @@ static void icount_warp_rt(void)
> }
> timers_state.qemu_icount_bias += warp_delta;
> }
> - vm_clock_warp_start = -1;
> + timers_state.vm_clock_warp_start = -1;
> seqlock_write_end(&timers_state.vm_clock_seqlock);
>
> if (qemu_clock_expired(QEMU_CLOCK_VIRTUAL)) {
> @@ -593,11 +593,13 @@ void qemu_start_warp_timer(void)
> * every 100ms.
> */
> seqlock_write_begin(&timers_state.vm_clock_seqlock);
> - if (vm_clock_warp_start == -1 || vm_clock_warp_start > clock) {
> - vm_clock_warp_start = clock;
> + if (timers_state.vm_clock_warp_start == -1
> + || timers_state.vm_clock_warp_start > clock) {
> + timers_state.vm_clock_warp_start = clock;
> }
> seqlock_write_end(&timers_state.vm_clock_seqlock);
> - timer_mod_anticipate(icount_warp_timer, clock + deadline);
> + timer_mod_anticipate(timers_state.icount_warp_timer,
> + clock + deadline);
> }
> } else if (deadline == 0) {
> qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
> @@ -622,7 +624,7 @@ static void qemu_account_warp_timer(void)
> return;
> }
>
> - timer_del(icount_warp_timer);
> + timer_del(timers_state.icount_warp_timer);
> icount_warp_rt();
> }
>
> @@ -631,6 +633,45 @@ static bool icount_state_needed(void *opaque)
> return use_icount;
> }
>
> +static bool warp_timer_state_needed(void *opaque)
> +{
> + TimersState *s = opaque;
> + return s->icount_warp_timer != NULL;
> +}
> +
> +static bool adjust_timers_state_needed(void *opaque)
> +{
> + TimersState *s = opaque;
> + return s->icount_rt_timer != NULL;
> +}
> +
> +/*
> + * Subsection for warp timer migration is optional, because may not be
> created
> + */
> +static const VMStateDescription icount_vmstate_warp_timer = {
> + .name = "timer/icount/warp_timer",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .needed = warp_timer_state_needed,
> + .fields = (VMStateField[]) {
> + VMSTATE_INT64(vm_clock_warp_start, TimersState),
> + VMSTATE_TIMER_PTR(icount_warp_timer, TimersState),
> + VMSTATE_END_OF_LIST()
> + }
> +};
> +
> +static const VMStateDescription icount_vmstate_adjust_timers = {
> + .name = "timer/icount/timers",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .needed = adjust_timers_state_needed,
> + .fields = (VMStateField[]) {
> + VMSTATE_TIMER_PTR(icount_rt_timer, TimersState),
> + VMSTATE_TIMER_PTR(icount_vm_timer, TimersState),
> + VMSTATE_END_OF_LIST()
> + }
> +};
> +
> /*
> * This is a subsection for icount migration.
> */
> @@ -643,6 +684,11 @@ static const VMStateDescription icount_vmstate_timers = {
> VMSTATE_INT64(qemu_icount_bias, TimersState),
> VMSTATE_INT64(qemu_icount, TimersState),
> VMSTATE_END_OF_LIST()
> + },
> + .subsections = (const VMStateDescription*[]) {
> + &icount_vmstate_warp_timer,
> + &icount_vmstate_adjust_timers,
> + NULL
> }
> };
>
> @@ -753,7 +799,7 @@ void configure_icount(QemuOpts *opts, Error **errp)
>
> icount_sleep = qemu_opt_get_bool(opts, "sleep", true);
> if (icount_sleep) {
> - icount_warp_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL_RT,
> + timers_state.icount_warp_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL_RT,
> icount_timer_cb, NULL);
> }
>
> @@ -787,13 +833,14 @@ void configure_icount(QemuOpts *opts, Error **errp)
> the virtual time trigger catches emulated time passing too fast.
> Realtime triggers occur even when idle, so use them less frequently
> than VM triggers. */
> - icount_rt_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL_RT,
> + timers_state.vm_clock_warp_start = -1;
> + timers_state.icount_rt_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL_RT,
> icount_adjust_rt, NULL);
> - timer_mod(icount_rt_timer,
> + timer_mod(timers_state.icount_rt_timer,
> qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL_RT) + 1000);
> - icount_vm_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
> + timers_state.icount_vm_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
> icount_adjust_vm, NULL);
> - timer_mod(icount_vm_timer,
> + timer_mod(timers_state.icount_vm_timer,
> qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
> NANOSECONDS_PER_SECOND / 10);
> }
>
Acked-by: Paolo Bonzini <pbonz...@redhat.com>
