| Message ID | 1433783045-8002-3-git-send-email-marc.zyngier@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Marc Zyngier <marc.zyngier@arm.com> writes: > As we're about to introduce some serious GIC-poking to the vgic code, > it is important to make sure that we're going to poke the part of > the GIC that belongs to the CPU we're about to run on (otherwise, > we'd end up with some unexpected interrupts firing)... > > Introducing a non-preemptible section in kvm_arch_vcpu_ioctl_run > prevents the problem from occuring. > > Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> > --- > arch/arm/kvm/arm.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c > index 46db690..4986300 100644 > --- a/arch/arm/kvm/arm.c > +++ b/arch/arm/kvm/arm.c > @@ -529,8 +529,18 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) > if (vcpu->arch.pause) > vcpu_pause(vcpu); > > + /* > + * Disarming the timer must be done with in a > + * preemptible context, as this call may sleep. > + */ > kvm_timer_flush_hwstate(vcpu); > > + /* > + * Preparing the interrupts to be injected also > + * involves poking the GIC, which must be done in a > + * non-preemptible context. > + */ > + preempt_disable(); > kvm_vgic_flush_hwstate(vcpu); > > local_irq_disable(); > @@ -546,6 +556,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) > if (ret <= 0 || need_new_vmid_gen(vcpu->kvm)) { > local_irq_enable(); > kvm_vgic_sync_hwstate(vcpu); > + preempt_enable(); > kvm_timer_sync_hwstate(vcpu); > continue; > } > @@ -580,6 +591,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) > > kvm_vgic_sync_hwstate(vcpu); > > + preempt_enable(); > + > kvm_timer_sync_hwstate(vcpu); > > ret = handle_exit(vcpu, run, ret);
On Mon, Jun 08, 2015 at 06:03:57PM +0100, Marc Zyngier wrote: > As we're about to introduce some serious GIC-poking to the vgic code, > it is important to make sure that we're going to poke the part of > the GIC that belongs to the CPU we're about to run on (otherwise, > we'd end up with some unexpected interrupts firing)... > > Introducing a non-preemptible section in kvm_arch_vcpu_ioctl_run > prevents the problem from occuring. > > Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> > --- > arch/arm/kvm/arm.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c > index 46db690..4986300 100644 > --- a/arch/arm/kvm/arm.c > +++ b/arch/arm/kvm/arm.c > @@ -529,8 +529,18 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) > if (vcpu->arch.pause) > vcpu_pause(vcpu); > > + /* > + * Disarming the timer must be done with in a s/with // > + * preemptible context, as this call may sleep. > + */ > kvm_timer_flush_hwstate(vcpu); > > + /* > + * Preparing the interrupts to be injected also > + * involves poking the GIC, which must be done in a > + * non-preemptible context. > + */ > + preempt_disable(); > kvm_vgic_flush_hwstate(vcpu); > > local_irq_disable(); > @@ -546,6 +556,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) > if (ret <= 0 || need_new_vmid_gen(vcpu->kvm)) { > local_irq_enable(); > kvm_vgic_sync_hwstate(vcpu); > + preempt_enable(); > kvm_timer_sync_hwstate(vcpu); > continue; > } > @@ -580,6 +591,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) > > kvm_vgic_sync_hwstate(vcpu); > > + preempt_enable(); > + > kvm_timer_sync_hwstate(vcpu); > > ret = handle_exit(vcpu, run, ret); > -- > 2.1.4 > This should get more simple when rebased on cpu time accounting patch, but otherwise looks good. -Christoffer
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 46db690..4986300 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -529,8 +529,18 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) if (vcpu->arch.pause) vcpu_pause(vcpu); + /* + * Disarming the timer must be done with in a + * preemptible context, as this call may sleep. + */ kvm_timer_flush_hwstate(vcpu); + /* + * Preparing the interrupts to be injected also + * involves poking the GIC, which must be done in a + * non-preemptible context. + */ + preempt_disable(); kvm_vgic_flush_hwstate(vcpu); local_irq_disable(); @@ -546,6 +556,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) if (ret <= 0 || need_new_vmid_gen(vcpu->kvm)) { local_irq_enable(); kvm_vgic_sync_hwstate(vcpu); + preempt_enable(); kvm_timer_sync_hwstate(vcpu); continue; } @@ -580,6 +591,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) kvm_vgic_sync_hwstate(vcpu); + preempt_enable(); + kvm_timer_sync_hwstate(vcpu); ret = handle_exit(vcpu, run, ret);
As we're about to introduce some serious GIC-poking to the vgic code, it is important to make sure that we're going to poke the part of the GIC that belongs to the CPU we're about to run on (otherwise, we'd end up with some unexpected interrupts firing)... Introducing a non-preemptible section in kvm_arch_vcpu_ioctl_run prevents the problem from occuring. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> --- arch/arm/kvm/arm.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)