| Message ID | 20171018164750.GI8900@cbox (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Oct 18 2017 at 6:47:50 pm BST, Christoffer Dall <cdall@linaro.org> wrote: > On Mon, Oct 09, 2017 at 06:05:04PM +0100, Marc Zyngier wrote: >> On 23/09/17 01:41, Christoffer Dall wrote: >> > We are about to add an additional soft timer to the arch timer state for >> > a VCPU and would like to be able to reuse the functions to program and >> > cancel a timer, so we make them slightly more generic and rename to make >> > it more clear that these functions work on soft timers and not the >> > hardware resource that this code is managing. >> > >> > Signed-off-by: Christoffer Dall <cdall@linaro.org> >> > --- >> > virt/kvm/arm/arch_timer.c | 33 ++++++++++++++++----------------- >> > 1 file changed, 16 insertions(+), 17 deletions(-) >> > >> > diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c >> > index 8e89d63..871d8ae 100644 >> > --- a/virt/kvm/arm/arch_timer.c >> > +++ b/virt/kvm/arm/arch_timer.c >> > @@ -56,26 +56,22 @@ u64 kvm_phys_timer_read(void) >> > return timecounter->cc->read(timecounter->cc); >> > } >> > >> > -static bool timer_is_armed(struct arch_timer_cpu *timer) >> > +static bool soft_timer_is_armed(struct arch_timer_cpu *timer) >> > { >> > return timer->armed; >> > } >> > >> > -/* timer_arm: as in "arm the timer", not as in ARM the company */ >> > -static void timer_arm(struct arch_timer_cpu *timer, u64 ns) >> > +static void soft_timer_start(struct hrtimer *hrt, u64 ns) >> > { >> > - timer->armed = true; >> > - hrtimer_start(&timer->timer, ktime_add_ns(ktime_get(), ns), >> > + hrtimer_start(hrt, ktime_add_ns(ktime_get(), ns), >> > HRTIMER_MODE_ABS); >> > } >> > >> > -static void timer_disarm(struct arch_timer_cpu *timer) >> > +static void soft_timer_cancel(struct hrtimer *hrt, struct work_struct *work) >> > { >> > - if (timer_is_armed(timer)) { >> > - hrtimer_cancel(&timer->timer); >> > - cancel_work_sync(&timer->expired); >> > - timer->armed = false; >> > - } >> > + hrtimer_cancel(hrt); >> > + if (work) >> >> When can this happen? Something in a following patch? >> > > Yeah, sorry about that. I will point this out in the commit message. > >> > + cancel_work_sync(work); >> > } >> > >> > static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id) >> > @@ -271,7 +267,7 @@ static void kvm_timer_emulate(struct kvm_vcpu *vcpu, >> > return; >> > >> > /* The timer has not yet expired, schedule a background timer */ >> > - timer_arm(timer, kvm_timer_compute_delta(timer_ctx)); >> > + soft_timer_start(&timer->timer, kvm_timer_compute_delta(timer_ctx)); >> > } >> > >> > /* >> > @@ -285,7 +281,7 @@ void kvm_timer_schedule(struct kvm_vcpu *vcpu) >> > struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); >> > struct arch_timer_context *ptimer = vcpu_ptimer(vcpu); >> > >> > - BUG_ON(timer_is_armed(timer)); >> > + BUG_ON(soft_timer_is_armed(timer)); >> > >> > /* >> > * No need to schedule a background timer if any guest timer has >> > @@ -306,13 +302,16 @@ void kvm_timer_schedule(struct kvm_vcpu *vcpu) >> > * The guest timers have not yet expired, schedule a background timer. >> > * Set the earliest expiration time among the guest timers. >> > */ >> > - timer_arm(timer, kvm_timer_earliest_exp(vcpu)); >> > + timer->armed = true; >> > + soft_timer_start(&timer->timer, kvm_timer_earliest_exp(vcpu)); >> > } >> > >> > void kvm_timer_unschedule(struct kvm_vcpu *vcpu) >> > { >> > struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; >> > - timer_disarm(timer); >> > + >> > + soft_timer_cancel(&timer->timer, &timer->expired); >> > + timer->armed = false; >> > } >> > >> > static void kvm_timer_flush_hwstate_vgic(struct kvm_vcpu *vcpu) >> > @@ -448,7 +447,7 @@ void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu) >> > * This is to cancel the background timer for the physical timer >> > * emulation if it is set. >> > */ >> > - timer_disarm(timer); >> > + soft_timer_cancel(&timer->timer, &timer->expired); >> >> timer_disarm() used to set timer->armed to false, but that's not the >> case any more. Don't we risk hitting the BUG_ON() in kvm_timer_schedule >> if we hit WFI? >> > > We do, and I just didn't hit that because this goes away at the end of > the series, and I didn't vigurously test every single patch in the > series (just a compile test). > > We actually only use the armed flag for the BUG_ON(), and I don't think > we need that check really. So I suggest simply merging this logic into > this patch: > > diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h > index f0053f884b4a..d0beae98f755 100644 > --- a/include/kvm/arm_arch_timer.h > +++ b/include/kvm/arm_arch_timer.h > @@ -48,9 +48,6 @@ struct arch_timer_cpu { > /* Work queued with the above timer expires */ > struct work_struct expired; > > - /* Background timer active */ > - bool armed; > - > /* Is the timer enabled */ > bool enabled; > }; > diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c > index 871d8ae52f9b..98643bc696a9 100644 > --- a/virt/kvm/arm/arch_timer.c > +++ b/virt/kvm/arm/arch_timer.c > @@ -56,11 +56,6 @@ u64 kvm_phys_timer_read(void) > return timecounter->cc->read(timecounter->cc); > } > > -static bool soft_timer_is_armed(struct arch_timer_cpu *timer) > -{ > - return timer->armed; > -} > - > static void soft_timer_start(struct hrtimer *hrt, u64 ns) > { > hrtimer_start(hrt, ktime_add_ns(ktime_get(), ns), > @@ -281,8 +276,6 @@ void kvm_timer_schedule(struct kvm_vcpu *vcpu) > struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); > struct arch_timer_context *ptimer = vcpu_ptimer(vcpu); > > - BUG_ON(soft_timer_is_armed(timer)); > - > /* > * No need to schedule a background timer if any guest timer has > * already expired, because kvm_vcpu_block will return before putting > @@ -302,7 +295,6 @@ void kvm_timer_schedule(struct kvm_vcpu *vcpu) > * The guest timers have not yet expired, schedule a background timer. > * Set the earliest expiration time among the guest timers. > */ > - timer->armed = true; > soft_timer_start(&timer->timer, kvm_timer_earliest_exp(vcpu)); > } > > @@ -311,7 +303,6 @@ void kvm_timer_unschedule(struct kvm_vcpu *vcpu) > struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; > > soft_timer_cancel(&timer->timer, &timer->expired); > - timer->armed = false; > } > > static void kvm_timer_flush_hwstate_vgic(struct kvm_vcpu *vcpu) Yes, this seems like a sensible thing to do. Thanks, M.
diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h index f0053f884b4a..d0beae98f755 100644 --- a/include/kvm/arm_arch_timer.h +++ b/include/kvm/arm_arch_timer.h @@ -48,9 +48,6 @@ struct arch_timer_cpu { /* Work queued with the above timer expires */ struct work_struct expired; - /* Background timer active */ - bool armed; - /* Is the timer enabled */ bool enabled; }; diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index 871d8ae52f9b..98643bc696a9 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -56,11 +56,6 @@ u64 kvm_phys_timer_read(void) return timecounter->cc->read(timecounter->cc); } -static bool soft_timer_is_armed(struct arch_timer_cpu *timer) -{ - return timer->armed; -} - static void soft_timer_start(struct hrtimer *hrt, u64 ns) { hrtimer_start(hrt, ktime_add_ns(ktime_get(), ns), @@ -281,8 +276,6 @@ void kvm_timer_schedule(struct kvm_vcpu *vcpu) struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); struct arch_timer_context *ptimer = vcpu_ptimer(vcpu); - BUG_ON(soft_timer_is_armed(timer)); - /* * No need to schedule a background timer if any guest timer has * already expired, because kvm_vcpu_block will return before putting @@ -302,7 +295,6 @@ void kvm_timer_schedule(struct kvm_vcpu *vcpu) * The guest timers have not yet expired, schedule a background timer. * Set the earliest expiration time among the guest timers. */ - timer->armed = true; soft_timer_start(&timer->timer, kvm_timer_earliest_exp(vcpu)); } @@ -311,7 +303,6 @@ void kvm_timer_unschedule(struct kvm_vcpu *vcpu) struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; soft_timer_cancel(&timer->timer, &timer->expired); - timer->armed = false; } static void kvm_timer_flush_hwstate_vgic(struct kvm_vcpu *vcpu)