From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim Deegan Subject: [PATCH 1/4] x86/hvm: Run the RTC periodic timer on a consistent time series. Date: Thu, 28 Mar 2013 16:09:27 +0000 Message-ID: <1364486970-14990-2-git-send-email-tim@xen.org> References: <1364486970-14990-1-git-send-email-tim@xen.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1364486970-14990-1-git-send-email-tim@xen.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: xen-devel@lists.xen.org Cc: suravee.suthikulpanit@amd.com, JBeulich@suse.com List-Id: xen-devel@lists.xenproject.org When the RTC periodic timer gets restarted, align it to the VM's boot time, not to whatever time it is now. Otherwise every read of REG_C will restart the current period Signed-off-by: Tim Deegan Acked-by: Keir Fraser --- xen/arch/x86/hvm/rtc.c | 6 ++++-- xen/include/asm-x86/hvm/vpt.h | 3 ++- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/xen/arch/x86/hvm/rtc.c b/xen/arch/x86/hvm/rtc.c index c1e09d8..e9aa81a 100644 --- a/xen/arch/x86/hvm/rtc.c +++ b/xen/arch/x86/hvm/rtc.c @@ -80,7 +80,7 @@ void rtc_periodic_interrupt(void *opaque) * RTC_RATE_SELECT settings */ static void rtc_timer_update(RTCState *s) { - int period_code, period; + int period_code, period, delta; struct vcpu *v = vrtc_vcpu(s); ASSERT(spin_is_locked(&s->lock)); @@ -98,7 +98,8 @@ static void rtc_timer_update(RTCState *s) { period = 1 << (period_code - 1); /* period in 32 Khz cycles */ period = DIV_ROUND(period * 1000000000ULL, 32768); /* in ns */ - create_periodic_time(v, &s->pt, period, period, RTC_IRQ, NULL, s); + delta = period - ((NOW() - s->start_time) % period); + create_periodic_time(v, &s->pt, delta, period, RTC_IRQ, NULL, s); break; } /* fall through */ @@ -740,6 +741,7 @@ void rtc_init(struct domain *d) s->hw.cmos_data[RTC_REG_D] = RTC_VRT; s->current_tm = gmtime(get_localtime(d)); + s->start_time = NOW(); rtc_copy_date(s); diff --git a/xen/include/asm-x86/hvm/vpt.h b/xen/include/asm-x86/hvm/vpt.h index c75297b..2e9c7d2 100644 --- a/xen/include/asm-x86/hvm/vpt.h +++ b/xen/include/asm-x86/hvm/vpt.h @@ -104,8 +104,9 @@ typedef struct RTCState { struct hvm_hw_rtc hw; /* RTC's idea of the current time */ struct tm current_tm; + /* periodic timer */ + s_time_t start_time; /* second update */ - int64_t next_second_time; struct periodic_time pt; /* update-ended timer */ struct timer update_timer; -- 1.7.10.4