* Pavel Dovgalyuk (pavel.dovga...@ispras.ru) wrote:
> HPET saves its state by calculating the current time and recovers timer
> offset using this calculated value. But these calculations include
> divisions and multiplications. Therefore the timer state cannot be recovered
> precise enough.
> This patch introduces saving of the original value of the offset to
> preserve the determinism of the timer.
Please put the extra data in a subsection and tie the subsection to a
property enabled by the machine type. That avoids breaking backwards
migration compatibility.
Dave
> Signed-off-by: Maria Klimushenkova <maria.klimushenk...@ispras.ru>
> Signed-off-by: Pavel Dovgalyuk <pavel.dovga...@ispras.ru>
>
> ---
> hw/timer/hpet.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/hw/timer/hpet.c b/hw/timer/hpet.c
> index 577371b..4cf6a5b 100644
> --- a/hw/timer/hpet.c
> +++ b/hw/timer/hpet.c
> @@ -221,7 +221,9 @@ static int hpet_pre_save(void *opaque)
> HPETState *s = opaque;
>
> /* save current counter value */
> - s->hpet_counter = hpet_get_ticks(s);
> + if (hpet_enabled(s)) {
> + s->hpet_counter = hpet_get_ticks(s);
> + }
>
> return 0;
> }
> @@ -252,7 +254,10 @@ static int hpet_post_load(void *opaque, int version_id)
> HPETState *s = opaque;
>
> /* Recalculate the offset between the main counter and guest time */
> - s->hpet_offset = ticks_to_ns(s->hpet_counter) -
> qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
> + if (version_id <= 2) {
> + s->hpet_offset = ticks_to_ns(s->hpet_counter)
> + - qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
> + }
>
> /* Push number of timers into capability returned via HPET_ID */
> s->capability &= ~HPET_ID_NUM_TIM_MASK;
> @@ -303,7 +308,7 @@ static const VMStateDescription vmstate_hpet_timer = {
>
> static const VMStateDescription vmstate_hpet = {
> .name = "hpet",
> - .version_id = 2,
> + .version_id = 3,
> .minimum_version_id = 1,
> .pre_save = hpet_pre_save,
> .pre_load = hpet_pre_load,
> @@ -312,6 +317,7 @@ static const VMStateDescription vmstate_hpet = {
> VMSTATE_UINT64(config, HPETState),
> VMSTATE_UINT64(isr, HPETState),
> VMSTATE_UINT64(hpet_counter, HPETState),
> + VMSTATE_UINT64_V(hpet_offset, HPETState, 3),
> VMSTATE_UINT8_V(num_timers, HPETState, 2),
> VMSTATE_VALIDATE("num_timers in range", hpet_validate_num_timers),
> VMSTATE_STRUCT_VARRAY_UINT8(timer, HPETState, num_timers, 0,
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
