* [PATCH] hw/i8254: fix vmstate load
@ 2021-03-10 10:21 Pavel Dovgalyuk
2021-03-10 10:27 ` Paolo Bonzini
2021-03-15 20:13 ` Dr. David Alan Gilbert
0 siblings, 2 replies; 5+ messages in thread
From: Pavel Dovgalyuk @ 2021-03-10 10:21 UTC (permalink / raw)
To: qemu-devel; +Cc: pbonzini, pavel.dovgalyuk, mst
QEMU timer of channel 0 in i8254 is used to raise irq
at the specified moment of time. This irq can be disabled
with irq_disabled flag. But when vmstate of the pit is
loaded, timer may be rearmed despite the disabled interrupts.
This patch adds irq_disabled flag check to fix that.
Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
---
hw/timer/i8254.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/hw/timer/i8254.c b/hw/timer/i8254.c
index c01ee2c72a..c8388ea432 100644
--- a/hw/timer/i8254.c
+++ b/hw/timer/i8254.c
@@ -324,7 +324,7 @@ static void pit_post_load(PITCommonState *s)
{
PITChannelState *sc = &s->channels[0];
- if (sc->next_transition_time != -1) {
+ if (sc->next_transition_time != -1 && !sc->irq_disabled) {
timer_mod(sc->irq_timer, sc->next_transition_time);
} else {
timer_del(sc->irq_timer);
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] hw/i8254: fix vmstate load
2021-03-10 10:21 [PATCH] hw/i8254: fix vmstate load Pavel Dovgalyuk
@ 2021-03-10 10:27 ` Paolo Bonzini
2021-03-15 20:13 ` Dr. David Alan Gilbert
1 sibling, 0 replies; 5+ messages in thread
From: Paolo Bonzini @ 2021-03-10 10:27 UTC (permalink / raw)
To: Pavel Dovgalyuk, qemu-devel; +Cc: mst
On 10/03/21 11:21, Pavel Dovgalyuk wrote:
> QEMU timer of channel 0 in i8254 is used to raise irq
> at the specified moment of time. This irq can be disabled
> with irq_disabled flag. But when vmstate of the pit is
> loaded, timer may be rearmed despite the disabled interrupts.
> This patch adds irq_disabled flag check to fix that.
>
> Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
> ---
> hw/timer/i8254.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/timer/i8254.c b/hw/timer/i8254.c
> index c01ee2c72a..c8388ea432 100644
> --- a/hw/timer/i8254.c
> +++ b/hw/timer/i8254.c
> @@ -324,7 +324,7 @@ static void pit_post_load(PITCommonState *s)
> {
> PITChannelState *sc = &s->channels[0];
>
> - if (sc->next_transition_time != -1) {
> + if (sc->next_transition_time != -1 && !sc->irq_disabled) {
> timer_mod(sc->irq_timer, sc->next_transition_time);
> } else {
> timer_del(sc->irq_timer);
>
Queued, thanks.
Paolo
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] hw/i8254: fix vmstate load
2021-03-10 10:21 [PATCH] hw/i8254: fix vmstate load Pavel Dovgalyuk
2021-03-10 10:27 ` Paolo Bonzini
@ 2021-03-15 20:13 ` Dr. David Alan Gilbert
2021-03-16 4:15 ` Pavel Dovgalyuk
1 sibling, 1 reply; 5+ messages in thread
From: Dr. David Alan Gilbert @ 2021-03-15 20:13 UTC (permalink / raw)
To: Pavel Dovgalyuk; +Cc: pbonzini, qemu-devel, mst
* Pavel Dovgalyuk (pavel.dovgalyuk@ispras.ru) wrote:
> QEMU timer of channel 0 in i8254 is used to raise irq
> at the specified moment of time. This irq can be disabled
> with irq_disabled flag. But when vmstate of the pit is
> loaded, timer may be rearmed despite the disabled interrupts.
> This patch adds irq_disabled flag check to fix that.
>
> Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Hi Pavel,
I'm curious, did you see this cause a problem on a particular guest
OS?
Dave
> ---
> hw/timer/i8254.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/timer/i8254.c b/hw/timer/i8254.c
> index c01ee2c72a..c8388ea432 100644
> --- a/hw/timer/i8254.c
> +++ b/hw/timer/i8254.c
> @@ -324,7 +324,7 @@ static void pit_post_load(PITCommonState *s)
> {
> PITChannelState *sc = &s->channels[0];
>
> - if (sc->next_transition_time != -1) {
> + if (sc->next_transition_time != -1 && !sc->irq_disabled) {
> timer_mod(sc->irq_timer, sc->next_transition_time);
> } else {
> timer_del(sc->irq_timer);
>
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] hw/i8254: fix vmstate load
2021-03-15 20:13 ` Dr. David Alan Gilbert
@ 2021-03-16 4:15 ` Pavel Dovgalyuk
2021-03-16 9:11 ` Dr. David Alan Gilbert
0 siblings, 1 reply; 5+ messages in thread
From: Pavel Dovgalyuk @ 2021-03-16 4:15 UTC (permalink / raw)
To: Dr. David Alan Gilbert; +Cc: pbonzini, qemu-devel, mst
On 15.03.2021 23:13, Dr. David Alan Gilbert wrote:
> * Pavel Dovgalyuk (pavel.dovgalyuk@ispras.ru) wrote:
>> QEMU timer of channel 0 in i8254 is used to raise irq
>> at the specified moment of time. This irq can be disabled
>> with irq_disabled flag. But when vmstate of the pit is
>> loaded, timer may be rearmed despite the disabled interrupts.
>> This patch adds irq_disabled flag check to fix that.
>>
>> Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
>
> Hi Pavel,
> I'm curious, did you see this cause a problem on a particular guest
> OS?
That was Windows 7 on i386.
I found this when tested reverse debugging.
>
> Dave
>
>> ---
>> hw/timer/i8254.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/hw/timer/i8254.c b/hw/timer/i8254.c
>> index c01ee2c72a..c8388ea432 100644
>> --- a/hw/timer/i8254.c
>> +++ b/hw/timer/i8254.c
>> @@ -324,7 +324,7 @@ static void pit_post_load(PITCommonState *s)
>> {
>> PITChannelState *sc = &s->channels[0];
>>
>> - if (sc->next_transition_time != -1) {
>> + if (sc->next_transition_time != -1 && !sc->irq_disabled) {
>> timer_mod(sc->irq_timer, sc->next_transition_time);
>> } else {
>> timer_del(sc->irq_timer);
>>
>>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] hw/i8254: fix vmstate load
2021-03-16 4:15 ` Pavel Dovgalyuk
@ 2021-03-16 9:11 ` Dr. David Alan Gilbert
0 siblings, 0 replies; 5+ messages in thread
From: Dr. David Alan Gilbert @ 2021-03-16 9:11 UTC (permalink / raw)
To: Pavel Dovgalyuk; +Cc: pbonzini, qemu-devel, mst
* Pavel Dovgalyuk (pavel.dovgalyuk@ispras.ru) wrote:
> On 15.03.2021 23:13, Dr. David Alan Gilbert wrote:
> > * Pavel Dovgalyuk (pavel.dovgalyuk@ispras.ru) wrote:
> > > QEMU timer of channel 0 in i8254 is used to raise irq
> > > at the specified moment of time. This irq can be disabled
> > > with irq_disabled flag. But when vmstate of the pit is
> > > loaded, timer may be rearmed despite the disabled interrupts.
> > > This patch adds irq_disabled flag check to fix that.
> > >
> > > Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
> >
> > Hi Pavel,
> > I'm curious, did you see this cause a problem on a particular guest
> > OS?
>
> That was Windows 7 on i386.
> I found this when tested reverse debugging.
Thanks; I like to know of migration fixes for when someone comes asking
why something obscure breaks under migration :-)
Dave
> >
> > Dave
> >
> > > ---
> > > hw/timer/i8254.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/hw/timer/i8254.c b/hw/timer/i8254.c
> > > index c01ee2c72a..c8388ea432 100644
> > > --- a/hw/timer/i8254.c
> > > +++ b/hw/timer/i8254.c
> > > @@ -324,7 +324,7 @@ static void pit_post_load(PITCommonState *s)
> > > {
> > > PITChannelState *sc = &s->channels[0];
> > > - if (sc->next_transition_time != -1) {
> > > + if (sc->next_transition_time != -1 && !sc->irq_disabled) {
> > > timer_mod(sc->irq_timer, sc->next_transition_time);
> > > } else {
> > > timer_del(sc->irq_timer);
> > >
> > >
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-03-16 9:12 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2021-03-10 10:21 [PATCH] hw/i8254: fix vmstate load Pavel Dovgalyuk
2021-03-10 10:27 ` Paolo Bonzini
2021-03-15 20:13 ` Dr. David Alan Gilbert
2021-03-16 4:15 ` Pavel Dovgalyuk
2021-03-16 9:11 ` Dr. David Alan Gilbert
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