| Message ID | 20171215141656.25815-3-christoffer.dall@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 15 Dec 2017 14:16:56 +0000, Christoffer Dall wrote: > > When enabling the timer on the first run, we fail to ever restore the > state and mark it as loaded. That means, that in the initial entry to > the VCPU ioctl, unless we exit to userspace for some reason such as a > pending signal, if the guest programs a timer and blocks, we will wait > forever, because we never read back the hardware state (the loaded flag > is not set), and so we think the timer is disabled, and we never > schedule a background soft timer. > > The end result? The VCPU blocks forever, and the only solution is to > kill the thread. > > Fixes: 4a2c4da1250d ("arm/arm64: KVM: Load the timer state when enabling the timer") > Reported-by: Marc Zyngier <marc.zyngier@arm.com> > Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> > --- > virt/kvm/arm/arch_timer.c | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > > diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c > index 14c018f990a7..cc29a8148328 100644 > --- a/virt/kvm/arm/arch_timer.c > +++ b/virt/kvm/arm/arch_timer.c > @@ -846,10 +846,7 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu) > no_vgic: > preempt_disable(); > timer->enabled = 1; > - if (!irqchip_in_kernel(vcpu->kvm)) > - kvm_timer_vcpu_load_user(vcpu); > - else > - kvm_timer_vcpu_load_vgic(vcpu); > + kvm_timer_vcpu_load(vcpu); > preempt_enable(); > > return 0; > -- > 2.14.2 > Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> Tested-by: Marc Zyngier <marc.zyngier@arm.com> M.
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index 14c018f990a7..cc29a8148328 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -846,10 +846,7 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu) no_vgic: preempt_disable(); timer->enabled = 1; - if (!irqchip_in_kernel(vcpu->kvm)) - kvm_timer_vcpu_load_user(vcpu); - else - kvm_timer_vcpu_load_vgic(vcpu); + kvm_timer_vcpu_load(vcpu); preempt_enable(); return 0;
When enabling the timer on the first run, we fail to ever restore the state and mark it as loaded. That means, that in the initial entry to the VCPU ioctl, unless we exit to userspace for some reason such as a pending signal, if the guest programs a timer and blocks, we will wait forever, because we never read back the hardware state (the loaded flag is not set), and so we think the timer is disabled, and we never schedule a background soft timer. The end result? The VCPU blocks forever, and the only solution is to kill the thread. Fixes: 4a2c4da1250d ("arm/arm64: KVM: Load the timer state when enabling the timer") Reported-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> --- virt/kvm/arm/arch_timer.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)