| Message ID | 1341853545-3023-2-git-send-email-avi@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Jul 09, 2012 at 08:05:40PM +0300, Avi Kivity wrote: > It's a write-only bit, set by the timer and cleared by the main loop. > Remove it. Retain the definition since ppc uses it. > > Signed-off-by: Avi Kivity <avi@redhat.com> > --- > arch/x86/kvm/timer.c | 8 ++------ > arch/x86/kvm/x86.c | 1 - > 2 files changed, 2 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/kvm/timer.c b/arch/x86/kvm/timer.c > index 6b85cc6..c28f838 100644 > --- a/arch/x86/kvm/timer.c > +++ b/arch/x86/kvm/timer.c > @@ -27,14 +27,10 @@ enum hrtimer_restart kvm_timer_fn(struct hrtimer *data) > /* > * There is a race window between reading and incrementing, but we do > * not care about potentially losing timer events in the !reinject > - * case anyway. Note: KVM_REQ_PENDING_TIMER is implicitly checked > - * in vcpu_enter_guest. So what about the part that says "KVM_REQ_PENDING_TIMER is implicitly checked in vcpu_enter_guest"? This patch drops the check. So now if timer triggers while vcpu is in userspace it will enter guest mode without injecting timer interrupt on the next ioctl(KVM_RUN). Or do I miss something here? > + * case anyway. > */ > - if (ktimer->reinject || !atomic_read(&ktimer->pending)) { > + if (ktimer->reinject || !atomic_read(&ktimer->pending)) > atomic_inc(&ktimer->pending); > - /* FIXME: this code should not know anything about vcpus */ > - kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu); > - } > > if (waitqueue_active(q)) > wake_up_interruptible(q); > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index ff0b487..ae07ef2 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -5437,7 +5437,6 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) > if (r <= 0) > break; > > - clear_bit(KVM_REQ_PENDING_TIMER, &vcpu->requests); > if (kvm_cpu_has_pending_timer(vcpu)) > kvm_inject_pending_timer_irqs(vcpu); > > -- > 1.7.11 > > -- > 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 -- Gleb. -- 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
On 07/10/2012 11:50 AM, Gleb Natapov wrote: > On Mon, Jul 09, 2012 at 08:05:40PM +0300, Avi Kivity wrote: > > It's a write-only bit, set by the timer and cleared by the main loop. > > Remove it. Retain the definition since ppc uses it. > > > > Signed-off-by: Avi Kivity <avi@redhat.com> > > --- > > arch/x86/kvm/timer.c | 8 ++------ > > arch/x86/kvm/x86.c | 1 - > > 2 files changed, 2 insertions(+), 7 deletions(-) > > > > diff --git a/arch/x86/kvm/timer.c b/arch/x86/kvm/timer.c > > index 6b85cc6..c28f838 100644 > > --- a/arch/x86/kvm/timer.c > > +++ b/arch/x86/kvm/timer.c > > @@ -27,14 +27,10 @@ enum hrtimer_restart kvm_timer_fn(struct hrtimer *data) > > /* > > * There is a race window between reading and incrementing, but we do > > * not care about potentially losing timer events in the !reinject > > - * case anyway. Note: KVM_REQ_PENDING_TIMER is implicitly checked > > - * in vcpu_enter_guest. > So what about the part that says "KVM_REQ_PENDING_TIMER is implicitly > checked in vcpu_enter_guest"? This patch drops the check. So now if > timer triggers while vcpu is in userspace it will enter guest mode > without injecting timer interrupt on the next ioctl(KVM_RUN). Or do I > miss something here? You're right, the bit appears to be write-only, but it isn't. The check inside the critical section for vcpu->requests reads it. I guess we can make the check explicit by doing a 'goto out' if the bit is set.
diff --git a/arch/x86/kvm/timer.c b/arch/x86/kvm/timer.c index 6b85cc6..c28f838 100644 --- a/arch/x86/kvm/timer.c +++ b/arch/x86/kvm/timer.c @@ -27,14 +27,10 @@ enum hrtimer_restart kvm_timer_fn(struct hrtimer *data) /* * There is a race window between reading and incrementing, but we do * not care about potentially losing timer events in the !reinject - * case anyway. Note: KVM_REQ_PENDING_TIMER is implicitly checked - * in vcpu_enter_guest. + * case anyway. */ - if (ktimer->reinject || !atomic_read(&ktimer->pending)) { + if (ktimer->reinject || !atomic_read(&ktimer->pending)) atomic_inc(&ktimer->pending); - /* FIXME: this code should not know anything about vcpus */ - kvm_make_request(KVM_REQ_PENDING_TIMER, vcpu); - } if (waitqueue_active(q)) wake_up_interruptible(q); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ff0b487..ae07ef2 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5437,7 +5437,6 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) if (r <= 0) break; - clear_bit(KVM_REQ_PENDING_TIMER, &vcpu->requests); if (kvm_cpu_has_pending_timer(vcpu)) kvm_inject_pending_timer_irqs(vcpu);
It's a write-only bit, set by the timer and cleared by the main loop. Remove it. Retain the definition since ppc uses it. Signed-off-by: Avi Kivity <avi@redhat.com> --- arch/x86/kvm/timer.c | 8 ++------ arch/x86/kvm/x86.c | 1 - 2 files changed, 2 insertions(+), 7 deletions(-)