| Message ID | 1476255172-3357-3-git-send-email-wanpeng.li@hotmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
2016-10-12 14:52+0800, Wanpeng Li: > From: Wanpeng Li <wanpeng.li@hotmail.com> > > Most windows guests still utilize APIC Timer periodic/oneshot mode > instead of tsc-deadline mode, and the APIC Timer periodic/oneshot > mode are still emulated by high overhead hrtimer on host. This patch > converts the expected expire time of the periodic/oneshot mode to > guest deadline tsc in order to leverage VMX preemption timer logic > for APIC Timer tsc-deadline mode. > > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: Radim Krčmář <rkrcmar@redhat.com> > Cc: Yunhong Jiang <yunhong.jiang@intel.com> > Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> > --- > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > @@ -1101,7 +1101,14 @@ static u32 apic_get_tmcct(struct kvm_lapic *apic) > apic->lapic_timer.period == 0) > return 0; > > - remaining = hrtimer_get_remaining(&apic->lapic_timer.timer); > + if (kvm_lapic_hv_timer_in_use(apic->vcpu)) { apic->lapic_timer.expired_period is set unconditionally, so the condition seems superfluous. > + ktime_t now; > + > + now = apic->lapic_timer.timer.base->get_time(); > + remaining = ktime_sub(apic->lapic_timer.expired_period, now); The name expired_period is weird for something that can be in the future ... maybe target_ns? > + } else > + remaining = hrtimer_get_remaining(&apic->lapic_timer.timer); > + > if (ktime_to_ns(remaining) < 0) > remaining = ktime_set(0, 0); > > @@ -1353,8 +1360,6 @@ static void start_sw_period(struct kvm_lapic *apic) > > /* lapic timer in oneshot or periodic mode */ > now = apic->lapic_timer.timer.base->get_time(); > - apic->lapic_timer.period = (u64)kvm_lapic_get_reg(apic, APIC_TMICT) > - * APIC_BUS_CYCLE_NS * apic->divide_count; I would gut start_sw_period() a bit more: the checking of minimal period is a bit misplaced, because it uses now() when the timer switched to hrtimers, but that could have been long after the timer was set, so we'd delay for no good reason. > if (!apic->lapic_timer.period) > return; Can this happen? (WARN_ONCE() if it is only a sanity check.) > @@ -1400,52 +1405,71 @@ bool kvm_lapic_hv_timer_in_use(struct kvm_vcpu *vcpu) > +void kvm_lapic_expired_hv_timer(struct kvm_vcpu *vcpu) > +{ > + struct kvm_lapic *apic = vcpu->arch.apic; > + > + WARN_ON(!apic->lapic_timer.hv_timer_in_use); > + WARN_ON(swait_active(&vcpu->wq)); > + cancel_hv_timer(apic); > + apic_timer_expired(apic); > + > + if (apic_lvtt_period(apic)) { > + ktime_t now; > + u64 tscl = rdtsc(); > + > + apic->lapic_timer.period = (u64)kvm_lapic_get_reg(apic, APIC_TMICT) > + * APIC_BUS_CYCLE_NS * apic->divide_count; > + > + if (!apic->lapic_timer.period) > + return; > + > + apic->lapic_timer.tscdeadline = kvm_read_l1_tsc(apic->vcpu, tscl) + > + nsec_to_cycles(apic->vcpu, apic->lapic_timer.period); > + now = apic->lapic_timer.timer.base->get_time(); > + apic->lapic_timer.expired_period = ktime_add_ns(now, apic->lapic_timer.period); > + > + start_hv_timer(apic); > + } > +} > +EXPORT_SYMBOL_GPL(kvm_lapic_expired_hv_timer); > + > @@ -1470,10 +1497,25 @@ static void start_apic_timer(struct kvm_lapic *apic) > { > atomic_set(&apic->lapic_timer.pending, 0); > > - if (apic_lvtt_period(apic) || apic_lvtt_oneshot(apic)) > - start_sw_period(apic); > - else if (apic_lvtt_tscdeadline(apic)) { > - if (!(kvm_x86_ops->set_hv_timer && start_hv_tscdeadline(apic))) > + if (apic_lvtt_period(apic) || apic_lvtt_oneshot(apic)) { > + ktime_t now; > + u64 tscl = rdtsc(); > + > + apic->lapic_timer.period = (u64)kvm_lapic_get_reg(apic, APIC_TMICT) > + * APIC_BUS_CYCLE_NS * apic->divide_count; > + > + if (!apic->lapic_timer.period) > + return; > + apic->lapic_timer.tscdeadline = kvm_read_l1_tsc(apic->vcpu, tscl) + > + nsec_to_cycles(apic->vcpu, apic->lapic_timer.period); > + now = apic->lapic_timer.timer.base->get_time(); > + apic->lapic_timer.expired_period = ktime_add_ns(now, apic->lapic_timer.period); This is the same code as in kvm_lapic_expired_hv_timer(), a helper function is in order. > + > + if (!(kvm_x86_ops->set_hv_timer && start_hv_timer(apic))) > + start_sw_period(apic); > + } else if (apic_lvtt_tscdeadline(apic)) { > + if (!(kvm_x86_ops->set_hv_timer && start_hv_timer(apic))) > start_sw_tscdeadline(apic); > } > } > @@ -1711,8 +1753,7 @@ u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu) > { > struct kvm_lapic *apic = vcpu->arch.apic; > > - if (!lapic_in_kernel(vcpu) || apic_lvtt_oneshot(apic) || > - apic_lvtt_period(apic)) rdmsr MSR_IA32_TSCDEADLINE has to return 0 when the timer is not in tsc deadline mode, so the condition should stay. (and check for apic_lvtt_tscdeadline(), but that is a unrelated cleanup.) > + if (!lapic_in_kernel(vcpu)) > return 0; > > return apic->lapic_timer.tscdeadline; Thanks. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
2016-10-13 1:41 GMT+08:00 Radim Krčmář <rkrcmar@redhat.com>: > 2016-10-12 14:52+0800, Wanpeng Li: >> From: Wanpeng Li <wanpeng.li@hotmail.com> >> >> Most windows guests still utilize APIC Timer periodic/oneshot mode >> instead of tsc-deadline mode, and the APIC Timer periodic/oneshot >> mode are still emulated by high overhead hrtimer on host. This patch >> converts the expected expire time of the periodic/oneshot mode to >> guest deadline tsc in order to leverage VMX preemption timer logic >> for APIC Timer tsc-deadline mode. >> >> Cc: Paolo Bonzini <pbonzini@redhat.com> >> Cc: Radim Krčmář <rkrcmar@redhat.com> >> Cc: Yunhong Jiang <yunhong.jiang@intel.com> >> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> >> --- >> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c >> @@ -1101,7 +1101,14 @@ static u32 apic_get_tmcct(struct kvm_lapic *apic) >> apic->lapic_timer.period == 0) >> return 0; >> >> - remaining = hrtimer_get_remaining(&apic->lapic_timer.timer); >> + if (kvm_lapic_hv_timer_in_use(apic->vcpu)) { > > apic->lapic_timer.expired_period is set unconditionally, so the > condition seems superfluous. Agreed. > >> + ktime_t now; >> + >> + now = apic->lapic_timer.timer.base->get_time(); >> + remaining = ktime_sub(apic->lapic_timer.expired_period, now); > > The name expired_period is weird for something that can be in the future > ... maybe target_ns? How about target_expiration? It should be ktime_t as the second parameter of hrtimer_start(). > >> + } else >> + remaining = hrtimer_get_remaining(&apic->lapic_timer.timer); >> + >> if (ktime_to_ns(remaining) < 0) >> remaining = ktime_set(0, 0); >> >> @@ -1353,8 +1360,6 @@ static void start_sw_period(struct kvm_lapic *apic) >> >> /* lapic timer in oneshot or periodic mode */ >> now = apic->lapic_timer.timer.base->get_time(); >> - apic->lapic_timer.period = (u64)kvm_lapic_get_reg(apic, APIC_TMICT) >> - * APIC_BUS_CYCLE_NS * apic->divide_count; > > I would gut start_sw_period() a bit more: the checking of minimal period > is a bit misplaced, because it uses now() when the timer switched to > hrtimers, but that could have been long after the timer was set, so we'd > delay for no good reason. Agreed. > >> if (!apic->lapic_timer.period) >> return; > > Can this happen? (WARN_ONCE() if it is only a sanity check.) Actually I catch several apic->lapic_timer.period == 0 here, in addition, the oneshot mode test of kvm-unit-tests/apic.flat will fail if change it to WARN_ONCE() instead of return directly. > >> @@ -1400,52 +1405,71 @@ bool kvm_lapic_hv_timer_in_use(struct kvm_vcpu *vcpu) >> +void kvm_lapic_expired_hv_timer(struct kvm_vcpu *vcpu) >> +{ >> + struct kvm_lapic *apic = vcpu->arch.apic; >> + >> + WARN_ON(!apic->lapic_timer.hv_timer_in_use); >> + WARN_ON(swait_active(&vcpu->wq)); >> + cancel_hv_timer(apic); >> + apic_timer_expired(apic); >> + >> + if (apic_lvtt_period(apic)) { >> + ktime_t now; >> + u64 tscl = rdtsc(); >> + >> + apic->lapic_timer.period = (u64)kvm_lapic_get_reg(apic, APIC_TMICT) >> + * APIC_BUS_CYCLE_NS * apic->divide_count; >> + >> + if (!apic->lapic_timer.period) >> + return; >> + >> + apic->lapic_timer.tscdeadline = kvm_read_l1_tsc(apic->vcpu, tscl) + >> + nsec_to_cycles(apic->vcpu, apic->lapic_timer.period); >> + now = apic->lapic_timer.timer.base->get_time(); >> + apic->lapic_timer.expired_period = ktime_add_ns(now, apic->lapic_timer.period); >> + >> + start_hv_timer(apic); >> + } >> +} >> +EXPORT_SYMBOL_GPL(kvm_lapic_expired_hv_timer); >> + >> @@ -1470,10 +1497,25 @@ static void start_apic_timer(struct kvm_lapic *apic) >> { >> atomic_set(&apic->lapic_timer.pending, 0); >> >> - if (apic_lvtt_period(apic) || apic_lvtt_oneshot(apic)) >> - start_sw_period(apic); >> - else if (apic_lvtt_tscdeadline(apic)) { >> - if (!(kvm_x86_ops->set_hv_timer && start_hv_tscdeadline(apic))) >> + if (apic_lvtt_period(apic) || apic_lvtt_oneshot(apic)) { >> + ktime_t now; >> + u64 tscl = rdtsc(); >> + >> + apic->lapic_timer.period = (u64)kvm_lapic_get_reg(apic, APIC_TMICT) >> + * APIC_BUS_CYCLE_NS * apic->divide_count; >> + >> + if (!apic->lapic_timer.period) >> + return; >> + apic->lapic_timer.tscdeadline = kvm_read_l1_tsc(apic->vcpu, tscl) + >> + nsec_to_cycles(apic->vcpu, apic->lapic_timer.period); >> + now = apic->lapic_timer.timer.base->get_time(); >> + apic->lapic_timer.expired_period = ktime_add_ns(now, apic->lapic_timer.period); > > This is the same code as in kvm_lapic_expired_hv_timer(), a helper > function is in order. Agreed. > >> + >> + if (!(kvm_x86_ops->set_hv_timer && start_hv_timer(apic))) >> + start_sw_period(apic); >> + } else if (apic_lvtt_tscdeadline(apic)) { >> + if (!(kvm_x86_ops->set_hv_timer && start_hv_timer(apic))) >> start_sw_tscdeadline(apic); >> } >> } >> @@ -1711,8 +1753,7 @@ u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu) >> { >> struct kvm_lapic *apic = vcpu->arch.apic; >> >> - if (!lapic_in_kernel(vcpu) || apic_lvtt_oneshot(apic) || >> - apic_lvtt_period(apic)) > > rdmsr MSR_IA32_TSCDEADLINE has to return 0 when the timer is not in tsc > deadline mode, so the condition should stay. (and check for > apic_lvtt_tscdeadline(), but that is a unrelated cleanup.) Agreed. I just sent out RFC V3 to handle these comments, thanks for your active review, Radim. It is really helpful. :) Regards, Wanpeng Li -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
2016-10-13 19:38 GMT+08:00 Wanpeng Li <kernellwp@gmail.com>: > 2016-10-13 1:41 GMT+08:00 Radim Krčmář <rkrcmar@redhat.com>: >> 2016-10-12 14:52+0800, Wanpeng Li: [...] >>> @@ -1711,8 +1753,7 @@ u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu) >>> { >>> struct kvm_lapic *apic = vcpu->arch.apic; >>> >>> - if (!lapic_in_kernel(vcpu) || apic_lvtt_oneshot(apic) || >>> - apic_lvtt_period(apic)) >> >> rdmsr MSR_IA32_TSCDEADLINE has to return 0 when the timer is not in tsc >> deadline mode, so the condition should stay. (and check for >> apic_lvtt_tscdeadline(), but that is a unrelated cleanup.) Actually I modify this function to get apic->lapic_timer.tscdeadline in kvm_arch_vcpu_load() for periodic/oneshot mode, I introduce another function to handle this in order to avoid break rdmsr MSR_IA32_TSCDEADLINE sanity check in RFC V3. Regards, Wanpeng Li -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index dad743e..f5a03ae 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1101,7 +1101,14 @@ static u32 apic_get_tmcct(struct kvm_lapic *apic) apic->lapic_timer.period == 0) return 0; - remaining = hrtimer_get_remaining(&apic->lapic_timer.timer); + if (kvm_lapic_hv_timer_in_use(apic->vcpu)) { + ktime_t now; + + now = apic->lapic_timer.timer.base->get_time(); + remaining = ktime_sub(apic->lapic_timer.expired_period, now); + } else + remaining = hrtimer_get_remaining(&apic->lapic_timer.timer); + if (ktime_to_ns(remaining) < 0) remaining = ktime_set(0, 0); @@ -1353,8 +1360,6 @@ static void start_sw_period(struct kvm_lapic *apic) /* lapic timer in oneshot or periodic mode */ now = apic->lapic_timer.timer.base->get_time(); - apic->lapic_timer.period = (u64)kvm_lapic_get_reg(apic, APIC_TMICT) - * APIC_BUS_CYCLE_NS * apic->divide_count; if (!apic->lapic_timer.period) return; @@ -1377,7 +1382,7 @@ static void start_sw_period(struct kvm_lapic *apic) } hrtimer_start(&apic->lapic_timer.timer, - ktime_add_ns(now, apic->lapic_timer.period), + apic->lapic_timer.expired_period, HRTIMER_MODE_ABS_PINNED); apic_debug("%s: bus cycle is %" PRId64 "ns, now 0x%016" @@ -1400,52 +1405,71 @@ bool kvm_lapic_hv_timer_in_use(struct kvm_vcpu *vcpu) } EXPORT_SYMBOL_GPL(kvm_lapic_hv_timer_in_use); -static void cancel_hv_tscdeadline(struct kvm_lapic *apic) +static void cancel_hv_timer(struct kvm_lapic *apic) { kvm_x86_ops->cancel_hv_timer(apic->vcpu); apic->lapic_timer.hv_timer_in_use = false; } -void kvm_lapic_expired_hv_timer(struct kvm_vcpu *vcpu) -{ - struct kvm_lapic *apic = vcpu->arch.apic; - - WARN_ON(!apic->lapic_timer.hv_timer_in_use); - WARN_ON(swait_active(&vcpu->wq)); - cancel_hv_tscdeadline(apic); - apic_timer_expired(apic); -} -EXPORT_SYMBOL_GPL(kvm_lapic_expired_hv_timer); - -static bool start_hv_tscdeadline(struct kvm_lapic *apic) +static bool start_hv_timer(struct kvm_lapic *apic) { u64 tscdeadline = apic->lapic_timer.tscdeadline; - if (atomic_read(&apic->lapic_timer.pending) || + if ((atomic_read(&apic->lapic_timer.pending) && + !apic_lvtt_period(apic)) || kvm_x86_ops->set_hv_timer(apic->vcpu, tscdeadline)) { if (apic->lapic_timer.hv_timer_in_use) - cancel_hv_tscdeadline(apic); + cancel_hv_timer(apic); } else { apic->lapic_timer.hv_timer_in_use = true; hrtimer_cancel(&apic->lapic_timer.timer); /* In case the sw timer triggered in the window */ - if (atomic_read(&apic->lapic_timer.pending)) - cancel_hv_tscdeadline(apic); + if (atomic_read(&apic->lapic_timer.pending) && + !apic_lvtt_period(apic)) + cancel_hv_timer(apic); } trace_kvm_hv_timer_state(apic->vcpu->vcpu_id, apic->lapic_timer.hv_timer_in_use); return apic->lapic_timer.hv_timer_in_use; } +void kvm_lapic_expired_hv_timer(struct kvm_vcpu *vcpu) +{ + struct kvm_lapic *apic = vcpu->arch.apic; + + WARN_ON(!apic->lapic_timer.hv_timer_in_use); + WARN_ON(swait_active(&vcpu->wq)); + cancel_hv_timer(apic); + apic_timer_expired(apic); + + if (apic_lvtt_period(apic)) { + ktime_t now; + u64 tscl = rdtsc(); + + apic->lapic_timer.period = (u64)kvm_lapic_get_reg(apic, APIC_TMICT) + * APIC_BUS_CYCLE_NS * apic->divide_count; + + if (!apic->lapic_timer.period) + return; + + apic->lapic_timer.tscdeadline = kvm_read_l1_tsc(apic->vcpu, tscl) + + nsec_to_cycles(apic->vcpu, apic->lapic_timer.period); + now = apic->lapic_timer.timer.base->get_time(); + apic->lapic_timer.expired_period = ktime_add_ns(now, apic->lapic_timer.period); + + start_hv_timer(apic); + } +} +EXPORT_SYMBOL_GPL(kvm_lapic_expired_hv_timer); + void kvm_lapic_switch_to_hv_timer(struct kvm_vcpu *vcpu) { struct kvm_lapic *apic = vcpu->arch.apic; WARN_ON(apic->lapic_timer.hv_timer_in_use); - if (apic_lvtt_tscdeadline(apic)) - start_hv_tscdeadline(apic); + start_hv_timer(apic); } EXPORT_SYMBOL_GPL(kvm_lapic_switch_to_hv_timer); @@ -1457,12 +1481,15 @@ void kvm_lapic_switch_to_sw_timer(struct kvm_vcpu *vcpu) if (!apic->lapic_timer.hv_timer_in_use) return; - cancel_hv_tscdeadline(apic); + cancel_hv_timer(apic); if (atomic_read(&apic->lapic_timer.pending)) return; - start_sw_tscdeadline(apic); + if (apic_lvtt_period(apic) || apic_lvtt_oneshot(apic)) + start_sw_period(apic); + else if (apic_lvtt_tscdeadline(apic)) + start_sw_tscdeadline(apic); } EXPORT_SYMBOL_GPL(kvm_lapic_switch_to_sw_timer); @@ -1470,10 +1497,25 @@ static void start_apic_timer(struct kvm_lapic *apic) { atomic_set(&apic->lapic_timer.pending, 0); - if (apic_lvtt_period(apic) || apic_lvtt_oneshot(apic)) - start_sw_period(apic); - else if (apic_lvtt_tscdeadline(apic)) { - if (!(kvm_x86_ops->set_hv_timer && start_hv_tscdeadline(apic))) + if (apic_lvtt_period(apic) || apic_lvtt_oneshot(apic)) { + ktime_t now; + u64 tscl = rdtsc(); + + apic->lapic_timer.period = (u64)kvm_lapic_get_reg(apic, APIC_TMICT) + * APIC_BUS_CYCLE_NS * apic->divide_count; + + if (!apic->lapic_timer.period) + return; + + apic->lapic_timer.tscdeadline = kvm_read_l1_tsc(apic->vcpu, tscl) + + nsec_to_cycles(apic->vcpu, apic->lapic_timer.period); + now = apic->lapic_timer.timer.base->get_time(); + apic->lapic_timer.expired_period = ktime_add_ns(now, apic->lapic_timer.period); + + if (!(kvm_x86_ops->set_hv_timer && start_hv_timer(apic))) + start_sw_period(apic); + } else if (apic_lvtt_tscdeadline(apic)) { + if (!(kvm_x86_ops->set_hv_timer && start_hv_timer(apic))) start_sw_tscdeadline(apic); } } @@ -1711,8 +1753,7 @@ u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu) { struct kvm_lapic *apic = vcpu->arch.apic; - if (!lapic_in_kernel(vcpu) || apic_lvtt_oneshot(apic) || - apic_lvtt_period(apic)) + if (!lapic_in_kernel(vcpu)) return 0; return apic->lapic_timer.tscdeadline; diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h index f60d01c..fea7602 100644 --- a/arch/x86/kvm/lapic.h +++ b/arch/x86/kvm/lapic.h @@ -15,6 +15,7 @@ struct kvm_timer { struct hrtimer timer; s64 period; /* unit: ns */ + ktime_t expired_period; u32 timer_mode; u32 timer_mode_mask; u64 tscdeadline;