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Re: [Qemu-devel] [PATCH v2] hpet: recover timer offset correctly
From: |
Pavel Dovgalyuk |
Subject: |
Re: [Qemu-devel] [PATCH v2] hpet: recover timer offset correctly |
Date: |
Tue, 9 Jan 2018 11:23:21 +0300 |
Ping?
Pavel Dovgalyuk
> -----Original Message-----
> From: Pavel Dovgalyuk [mailto:address@hidden
> Sent: Wednesday, December 20, 2017 1:02 PM
> To: address@hidden
> Cc: address@hidden; address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden
> Subject: [PATCH v2] hpet: recover timer offset correctly
>
> 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.
>
> Signed-off-by: Maria Klimushenkova <address@hidden>
> Signed-off-by: Pavel Dovgalyuk <address@hidden>
> ---
> hw/timer/hpet.c | 32 ++++++++++++++++++++++++++++++--
> 1 file changed, 30 insertions(+), 2 deletions(-)
>
> diff --git a/hw/timer/hpet.c b/hw/timer/hpet.c
> index 577371b..4904a60 100644
> --- a/hw/timer/hpet.c
> +++ b/hw/timer/hpet.c
> @@ -70,6 +70,7 @@ typedef struct HPETState {
>
> MemoryRegion iomem;
> uint64_t hpet_offset;
> + bool hpet_offset_loaded;
> qemu_irq irqs[HPET_NUM_IRQ_ROUTES];
> uint32_t flags;
> uint8_t rtc_irq_level;
> @@ -221,7 +222,9 @@ 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;
> }
> @@ -232,6 +235,8 @@ static int hpet_pre_load(void *opaque)
>
> /* version 1 only supports 3, later versions will load the actual value
> */
> s->num_timers = HPET_MIN_TIMERS;
> + /* for checking whether the hpet_offset section is loaded */
> + s->hpet_offset_loaded = false;
> return 0;
> }
>
> @@ -252,7 +257,10 @@ 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 (!s->hpet_offset_loaded) {
> + 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;
> @@ -267,6 +275,14 @@ static int hpet_post_load(void *opaque, int version_id)
> return 0;
> }
>
> +static int hpet_offset_post_load(void *opaque, int version_id)
> +{
> + HPETState *s = opaque;
> +
> + s->hpet_offset_loaded = true;
> + return 0;
> +}
> +
> static bool hpet_rtc_irq_level_needed(void *opaque)
> {
> HPETState *s = opaque;
> @@ -285,6 +301,17 @@ static const VMStateDescription
> vmstate_hpet_rtc_irq_level = {
> }
> };
>
> +static const VMStateDescription vmstate_hpet_offset = {
> + .name = "hpet/offset",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .post_load = hpet_offset_post_load,
> + .fields = (VMStateField[]) {
> + VMSTATE_UINT64(hpet_offset, HPETState),
> + VMSTATE_END_OF_LIST()
> + }
> +};
> +
> static const VMStateDescription vmstate_hpet_timer = {
> .name = "hpet_timer",
> .version_id = 1,
> @@ -320,6 +347,7 @@ static const VMStateDescription vmstate_hpet = {
> },
> .subsections = (const VMStateDescription*[]) {
> &vmstate_hpet_rtc_irq_level,
> + &vmstate_hpet_offset,
> NULL
> }
> };
- Re: [Qemu-devel] [PATCH v2] hpet: recover timer offset correctly,
Pavel Dovgalyuk <=