From ecaa2629f2eb90048a18bcc1df430328cc0371be Mon Sep 17 00:00:00 2001 From: Tim Deegan Date: Thu, 28 Mar 2013 13:07:06 +0000 Subject: x86/hvm: Let the guest miss a few ticks before resetting the timer. Signed-off-by: Tim Deegan Acked-by: Jan Beulich Acked-by: Keir Fraser --- xen/arch/x86/hvm/rtc.c | 15 +++++++++------ xen/include/asm-x86/hvm/vpt.h | 1 + 2 files changed, 10 insertions(+), 6 deletions(-) diff --git a/xen/arch/x86/hvm/rtc.c b/xen/arch/x86/hvm/rtc.c index 8d9195fa49..88cacd1caf 100644 --- a/xen/arch/x86/hvm/rtc.c +++ b/xen/arch/x86/hvm/rtc.c @@ -65,17 +65,18 @@ void rtc_periodic_interrupt(void *opaque) RTCState *s = opaque; spin_lock(&s->lock); - if ( s->hw.cmos_data[RTC_REG_C] & RTC_PF ) - { - destroy_periodic_time(&s->pt); - s->pt_code = 0; - } - else + if ( !(s->hw.cmos_data[RTC_REG_C] & RTC_PF) ) { s->hw.cmos_data[RTC_REG_C] |= RTC_PF; if ( s->hw.cmos_data[RTC_REG_B] & RTC_PIE ) rtc_toggle_irq(s); } + else if ( ++(s->pt_dead_ticks) >= 10 ) + { + /* VM is ignoring its RTC; no point in running the timer */ + destroy_periodic_time(&s->pt); + s->pt_code = 0; + } spin_unlock(&s->lock); } @@ -88,6 +89,8 @@ static void rtc_timer_update(RTCState *s) ASSERT(spin_is_locked(&s->lock)); + s->pt_dead_ticks = 0; + period_code = s->hw.cmos_data[RTC_REG_A] & RTC_RATE_SELECT; switch ( s->hw.cmos_data[RTC_REG_A] & RTC_DIV_CTL ) { diff --git a/xen/include/asm-x86/hvm/vpt.h b/xen/include/asm-x86/hvm/vpt.h index ea9df426d5..765fbb7791 100644 --- a/xen/include/asm-x86/hvm/vpt.h +++ b/xen/include/asm-x86/hvm/vpt.h @@ -114,6 +114,7 @@ typedef struct RTCState { struct periodic_time pt; s_time_t start_time; int pt_code; + uint8_t pt_dead_ticks; uint32_t use_timer; spinlock_t lock; } RTCState; -- cgit v1.2.3