[PATCH 20/22] KVM: arm/arm64: Let the timer expire in hardirq context on RT

Marc Zyngier
2019-11-20T16:50:37Z

From: Thomas Gleixner <tglx@linutronix.de>

The timers are canceled from an preempt-notifier which is invoked with
disabled preemption which is not allowed on PREEMPT_RT.
The timer callback is short so in could be invoked in hard-IRQ context
on -RT.

Let the timer expire on hard-IRQ context even on -RT.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Tested-by: Julien Grall <julien.grall@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20191107095424.16647-1-bigeasy@linutronix.de
---
virt/kvm/arm/arch_timer.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index e2bb5bd60227..f182b2380345 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -80,7 +80,7 @@ static inline bool userspace_irqchip(struct kvm *kvm)
static void soft_timer_start(struct hrtimer *hrt, u64 ns)
{
hrtimer_start(hrt, ktime_add_ns(ktime_get(), ns),
- HRTIMER_MODE_ABS);
+ HRTIMER_MODE_ABS_HARD);
}

static void soft_timer_cancel(struct hrtimer *hrt)
@@ -697,11 +697,11 @@ void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
update_vtimer_cntvoff(vcpu, kvm_phys_timer_read());
ptimer->cntvoff = 0;

- hrtimer_init(&timer->bg_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+ hrtimer_init(&timer->bg_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_HARD);
timer->bg_timer.function = kvm_bg_timer_expire;

- hrtimer_init(&vtimer->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
- hrtimer_init(&ptimer->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+ hrtimer_init(&vtimer->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_HARD);
+ hrtimer_init(&ptimer->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_HARD);
vtimer->hrtimer.function = kvm_hrtimer_expire;
ptimer->hrtimer.function = kvm_hrtimer_expire;