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@xxxxxxx>
> Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
> ---
> 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@xxxxxxx>
Tested-by: Marc Zyngier <marc.zyngier@xxxxxxx>
M.
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