From: Jan Beulich Date: Mon, 3 Sep 2012 06:35:41 +0000 (+0200) Subject: x86/HVM: RTC periodic timer emulation adjustments X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~7997 X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/%22/%22http:/www.example.com/cgi/%22?a=commitdiff_plain;h=f1297904185f73262522b6277252bfb699644766;p=xen.git 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 Acked-by: Keir Fraser --- diff --git a/xen/arch/x86/hvm/rtc.c b/xen/arch/x86/hvm/rtc.c index d52a828365..ea5179a4b4 100644 --- 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, uint32_t addr, uint32_t data) { 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, uint32_t addr, uint32_t data) 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, uint32_t addr, uint32_t data) 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_UIP ) + rtc_timer_update(s); break; case RTC_REG_B: if ( data & RTC_SET ) @@ -436,7 +438,8 @@ static int rtc_ioport_write(void *opaque, uint32_t addr, uint32_t data) 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;