From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59164) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eYpBw-0006Ls-V6 for qemu-devel@nongnu.org; Tue, 09 Jan 2018 03:23:30 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eYpBu-0004rA-AL for qemu-devel@nongnu.org; Tue, 09 Jan 2018 03:23:28 -0500 Received: from mail.ispras.ru ([83.149.199.45]:39752) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eYpBt-0004mX-TG for qemu-devel@nongnu.org; Tue, 09 Jan 2018 03:23:26 -0500 From: "Pavel Dovgalyuk" References: <20171220100205.16625.84632.stgit@pasha-VirtualBox> In-Reply-To: <20171220100205.16625.84632.stgit@pasha-VirtualBox> Date: Tue, 9 Jan 2018 11:23:21 +0300 Message-ID: <003c01d38923$1c5157f0$54f407d0$@ru> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Content-Language: ru Subject: Re: [Qemu-devel] [PATCH v2] hpet: recover timer offset correctly List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: 'Pavel Dovgalyuk' , qemu-devel@nongnu.org Cc: quintela@redhat.com, mst@redhat.com, dgilbert@redhat.com, maria.klimushenkova@ispras.ru, pbonzini@redhat.com Ping? Pavel Dovgalyuk > -----Original Message----- > From: Pavel Dovgalyuk [mailto:Pavel.Dovgaluk@ispras.ru] > Sent: Wednesday, December 20, 2017 1:02 PM > To: qemu-devel@nongnu.org > Cc: quintela@redhat.com; mst@redhat.com; dgilbert@redhat.com; maria.klimushenkova@ispras.ru; > dovgaluk@ispras.ru; pavel.dovgaluk@ispras.ru; pbonzini@redhat.com > 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 > Signed-off-by: Pavel Dovgalyuk > --- > 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 > } > };