* [PATCH, v3] x86/HVM: RTC periodic timer emulation adjustments
@ 2012-08-31 16:01 Jan Beulich
2012-08-31 16:50 ` Keir Fraser
0 siblings, 1 reply; 3+ messages in thread
From: Jan Beulich @ 2012-08-31 16:01 UTC (permalink / raw)
To: xen-devel
[-- Attachment #1: Type: text/plain, Size: 1837 bytes --]
- don't call rtc_timer_update() on REG_A writes when the value didn't
change (doing the call always was reported to cause wall clock time
lagging with the JVM running on Windows)
- don't call rtc_timer_update() on REG_B writes when RTC_PIE didn't
change
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v3: Break out just this change from the previously submitted much
larger patch. The rest of that one is now planned to go in only
after 4.2.
--- a/xen/arch/x86/hvm/rtc.c
+++ b/xen/arch/x86/hvm/rtc.c
@@ -365,6 +365,7 @@ static int rtc_ioport_write(void *opaque
{
RTCState *s = opaque;
struct domain *d = vrtc_domain(s);
+ uint32_t orig;
spin_lock(&s->lock);
@@ -382,6 +383,7 @@ static int rtc_ioport_write(void *opaque
return 0;
}
+ orig = s->hw.cmos_data[s->hw.cmos_index];
switch ( s->hw.cmos_index )
{
case RTC_SECONDS_ALARM:
@@ -405,9 +407,9 @@ static int rtc_ioport_write(void *opaque
break;
case RTC_REG_A:
/* UIP bit is read only */
- s->hw.cmos_data[RTC_REG_A] = (data & ~RTC_UIP) |
- (s->hw.cmos_data[RTC_REG_A] & RTC_UIP);
- rtc_timer_update(s);
+ s->hw.cmos_data[RTC_REG_A] = (data & ~RTC_UIP) | (orig & RTC_UIP);
+ if ( (data ^ orig) & (RTC_RATE_SELECT | RTC_DIV_CTL) )
+ rtc_timer_update(s);
break;
case RTC_REG_B:
if ( data & RTC_SET )
@@ -436,7 +438,8 @@ static int rtc_ioport_write(void *opaque
hvm_isa_irq_assert(d, RTC_IRQ);
}
s->hw.cmos_data[RTC_REG_B] = data;
- rtc_timer_update(s);
+ if ( (data ^ orig) & RTC_PIE )
+ rtc_timer_update(s);
check_update_timer(s);
alarm_timer_update(s);
break;
[-- Attachment #2: x86-hvm-rtc-periodic.patch --]
[-- Type: text/plain, Size: 1884 bytes --]
x86/HVM: RTC periodic timer emulation adjustments
- don't call rtc_timer_update() on REG_A writes when the value didn't
change (doing the call always was reported to cause wall clock time
lagging with the JVM running on Windows)
- don't call rtc_timer_update() on REG_B writes when RTC_PIE didn't
change
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v3: Break out just this change from the previously submitted much
larger patch. The rest of that one is now planned to go in only
after 4.2.
--- a/xen/arch/x86/hvm/rtc.c
+++ b/xen/arch/x86/hvm/rtc.c
@@ -365,6 +365,7 @@ static int rtc_ioport_write(void *opaque
{
RTCState *s = opaque;
struct domain *d = vrtc_domain(s);
+ uint32_t orig;
spin_lock(&s->lock);
@@ -382,6 +383,7 @@ static int rtc_ioport_write(void *opaque
return 0;
}
+ orig = s->hw.cmos_data[s->hw.cmos_index];
switch ( s->hw.cmos_index )
{
case RTC_SECONDS_ALARM:
@@ -405,9 +407,9 @@ static int rtc_ioport_write(void *opaque
break;
case RTC_REG_A:
/* UIP bit is read only */
- s->hw.cmos_data[RTC_REG_A] = (data & ~RTC_UIP) |
- (s->hw.cmos_data[RTC_REG_A] & RTC_UIP);
- rtc_timer_update(s);
+ s->hw.cmos_data[RTC_REG_A] = (data & ~RTC_UIP) | (orig & RTC_UIP);
+ if ( (data ^ orig) & (RTC_RATE_SELECT | RTC_DIV_CTL) )
+ rtc_timer_update(s);
break;
case RTC_REG_B:
if ( data & RTC_SET )
@@ -436,7 +438,8 @@ static int rtc_ioport_write(void *opaque
hvm_isa_irq_assert(d, RTC_IRQ);
}
s->hw.cmos_data[RTC_REG_B] = data;
- rtc_timer_update(s);
+ if ( (data ^ orig) & RTC_PIE )
+ rtc_timer_update(s);
check_update_timer(s);
alarm_timer_update(s);
break;
[-- Attachment #3: Type: text/plain, Size: 126 bytes --]
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH, v3] x86/HVM: RTC periodic timer emulation adjustments
2012-08-31 16:01 [PATCH, v3] x86/HVM: RTC periodic timer emulation adjustments Jan Beulich
@ 2012-08-31 16:50 ` Keir Fraser
2012-09-03 6:42 ` Jan Beulich
0 siblings, 1 reply; 3+ messages in thread
From: Keir Fraser @ 2012-08-31 16:50 UTC (permalink / raw)
To: Jan Beulich, xen-devel
On 31/08/2012 17:01, "Jan Beulich" <JBeulich@suse.com> wrote:
> - don't call rtc_timer_update() on REG_A writes when the value didn't
> change (doing the call always was reported to cause wall clock time
> lagging with the JVM running on Windows)
> - don't call rtc_timer_update() on REG_B writes when RTC_PIE didn't
> change
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
One comment below in-line.
> ---
> v3: Break out just this change from the previously submitted much
> larger patch. The rest of that one is now planned to go in only
> after 4.2.
>
> --- a/xen/arch/x86/hvm/rtc.c
> +++ b/xen/arch/x86/hvm/rtc.c
> @@ -365,6 +365,7 @@ static int rtc_ioport_write(void *opaque
> {
> RTCState *s = opaque;
> struct domain *d = vrtc_domain(s);
> + uint32_t orig;
>
> spin_lock(&s->lock);
>
> @@ -382,6 +383,7 @@ static int rtc_ioport_write(void *opaque
> return 0;
> }
>
> + orig = s->hw.cmos_data[s->hw.cmos_index];
> switch ( s->hw.cmos_index )
> {
> case RTC_SECONDS_ALARM:
> @@ -405,9 +407,9 @@ static int rtc_ioport_write(void *opaque
> break;
> case RTC_REG_A:
> /* UIP bit is read only */
> - s->hw.cmos_data[RTC_REG_A] = (data & ~RTC_UIP) |
> - (s->hw.cmos_data[RTC_REG_A] & RTC_UIP);
> - rtc_timer_update(s);
> + s->hw.cmos_data[RTC_REG_A] = (data & ~RTC_UIP) | (orig & RTC_UIP);
> + if ( (data ^ orig) & (RTC_RATE_SELECT | RTC_DIV_CTL) )
Please change to 'if ( (data ^ orig) & ~RTC_UIP )'. It is shorter and
matches the style of the immediately preceding line.
Once you make this change:
Acked-by: Keir Fraser <keir@xen.org>
-- Keir
> + rtc_timer_update(s);
> break;
> case RTC_REG_B:
> if ( data & RTC_SET )
> @@ -436,7 +438,8 @@ static int rtc_ioport_write(void *opaque
> hvm_isa_irq_assert(d, RTC_IRQ);
> }
> s->hw.cmos_data[RTC_REG_B] = data;
> - rtc_timer_update(s);
> + if ( (data ^ orig) & RTC_PIE )
> + rtc_timer_update(s);
> check_update_timer(s);
> alarm_timer_update(s);
> break;
>
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH, v3] x86/HVM: RTC periodic timer emulation adjustments
2012-08-31 16:50 ` Keir Fraser
@ 2012-09-03 6:42 ` Jan Beulich
0 siblings, 0 replies; 3+ messages in thread
From: Jan Beulich @ 2012-09-03 6:42 UTC (permalink / raw)
To: Keir Fraser; +Cc: xen-devel
>>> On 31.08.12 at 18:50, Keir Fraser <keir.xen@gmail.com> wrote:
> On 31/08/2012 17:01, "Jan Beulich" <JBeulich@suse.com> wrote:
>> @@ -405,9 +407,9 @@ static int rtc_ioport_write(void *opaque
>> break;
>> case RTC_REG_A:
>> /* UIP bit is read only */
>> - s->hw.cmos_data[RTC_REG_A] = (data & ~RTC_UIP) |
>> - (s->hw.cmos_data[RTC_REG_A] & RTC_UIP);
>> - rtc_timer_update(s);
>> + s->hw.cmos_data[RTC_REG_A] = (data & ~RTC_UIP) | (orig & RTC_UIP);
>> + if ( (data ^ orig) & (RTC_RATE_SELECT | RTC_DIV_CTL) )
>
> Please change to 'if ( (data ^ orig) & ~RTC_UIP )'. It is shorter and
> matches the style of the immediately preceding line.
>
> Once you make this change:
> Acked-by: Keir Fraser <keir@xen.org>
I made the change before committing, albeit I disagree - what
we care about here are explicitly the two fields that the original
version named. Their mask just accidentally happens to be the
complement of RTC_UIP. Whereas in the lines above we
specifically care about that one flag...
Jan
^ permalink raw reply [flat|nested] 3+ messages in thread
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2012-08-31 16:01 [PATCH, v3] x86/HVM: RTC periodic timer emulation adjustments Jan Beulich
2012-08-31 16:50 ` Keir Fraser
2012-09-03 6:42 ` Jan Beulich
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