From fe842225f2d2dd71c97cff7ce2cea157328c4e9c Mon Sep 17 00:00:00 2001 From: Kouya Shimura Date: Wed, 23 Sep 2015 09:07:18 +0200 Subject: [PATCH] x86/hvm: fix saved pmtimer and hpet values The ACPI PM timer is sometimes broken on live migration. Since vcpu->arch.hvm_vcpu.guest_time is always zero in other than "delay for missed ticks mode". Even in "delay for missed ticks mode", vcpu's guest_time field is not valid (i.e. zero) when the state of vcpu is "blocked". (see pt_save_timer function) The original author (Tim Deegan) of pmtimer_save() must have intended that it saves the last scheduled time of the vcpu. Unfortunately it was already implied this bug. FYI, there is no other timer mode than "delay for missed ticks mode" then. For consistency with HPET, pmtimer_save() should refer hvm_get_guest_time() to update the counter as well as hpet_save() does. Without this patch, the clock of windows server 2012R2 without HPET might leap forward several minutes on live migration. Signed-off-by: Kouya Shimura Retain use of ->arch.hvm_vcpu.guest_time when non-zero. Do the inverse adjustment for vHPET. Signed-off-by: Jan Beulich Reviewed-by: Tim Deegan Reviewed-by: Kouya Shimura master commit: 244582a01dcb49fa30083725964a066937cc94f2 master date: 2015-09-11 16:24:56 +0200 --- xen/arch/x86/hvm/hpet.c | 4 +++- xen/arch/x86/hvm/pmtimer.c | 10 ++++++---- 2 files changed, 9 insertions(+), 5 deletions(-) diff --git a/xen/arch/x86/hvm/hpet.c b/xen/arch/x86/hvm/hpet.c index bdfc6fc750..9ca8259c0d 100644 --- a/xen/arch/x86/hvm/hpet.c +++ b/xen/arch/x86/hvm/hpet.c @@ -506,11 +506,13 @@ const struct hvm_mmio_handler hpet_mmio_handler = { static int hpet_save(struct domain *d, hvm_domain_context_t *h) { HPETState *hp = domain_vhpet(d); + struct vcpu *v = pt_global_vcpu_target(d); int rc; uint64_t guest_time; write_lock(&hp->lock); - guest_time = guest_time_hpet(hp); + guest_time = (v->arch.hvm_vcpu.guest_time ?: hvm_get_guest_time(v)) / + STIME_PER_HPET_TICK; /* Write the proper value into the main counter */ if ( hpet_enabled(hp) ) diff --git a/xen/arch/x86/hvm/pmtimer.c b/xen/arch/x86/hvm/pmtimer.c index 6ad2797986..0f79e84953 100644 --- a/xen/arch/x86/hvm/pmtimer.c +++ b/xen/arch/x86/hvm/pmtimer.c @@ -250,10 +250,12 @@ static int pmtimer_save(struct domain *d, hvm_domain_context_t *h) spin_lock(&s->lock); - /* Update the counter to the guest's current time. We always save - * with the domain paused, so the saved time should be after the - * last_gtime, but just in case, make sure we only go forwards */ - x = ((s->vcpu->arch.hvm_vcpu.guest_time - s->last_gtime) * s->scale) >> 32; + /* + * Update the counter to the guest's current time. Make sure it only + * goes forwards. + */ + x = (((s->vcpu->arch.hvm_vcpu.guest_time ?: hvm_get_guest_time(s->vcpu)) - + s->last_gtime) * s->scale) >> 32; if ( x < 1UL<<31 ) s->pm.tmr_val += x; if ( (s->pm.tmr_val & TMR_VAL_MSB) != msb )