From: Sebastian Andrzej Siewior Date: Fri, 26 Jul 2019 18:30:55 +0000 (+0200) Subject: KVM: LAPIC: Mark hrtimer to expire in hard interrupt context X-Git-Tag: v5.4-rc1~159^2~71 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=2c0d278f3293fc59da0d183075415ca1e8c93b40;p=platform%2Fkernel%2Flinux-rpi.git KVM: LAPIC: Mark hrtimer to expire in hard interrupt context On PREEMPT_RT enabled kernels unmarked hrtimers are moved into soft interrupt expiry mode by default. While that's not a functional requirement for the KVM local APIC timer emulation, it's a latency issue which can be avoided by marking the timer so hard interrupt context expiry is enforced. No functional change. [ tglx: Split out from larger combo patch. Add changelog. ] Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Acked-by: Paolo Bonzini Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20190726185753.363363474@linutronix.de --- diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 0aa1586..b9e5160 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1601,7 +1601,7 @@ static void start_sw_tscdeadline(struct kvm_lapic *apic) likely(ns > apic->lapic_timer.timer_advance_ns)) { expire = ktime_add_ns(now, ns); expire = ktime_sub_ns(expire, ktimer->timer_advance_ns); - hrtimer_start(&ktimer->timer, expire, HRTIMER_MODE_ABS); + hrtimer_start(&ktimer->timer, expire, HRTIMER_MODE_ABS_HARD); } else apic_timer_expired(apic); @@ -2302,7 +2302,7 @@ int kvm_create_lapic(struct kvm_vcpu *vcpu, int timer_advance_ns) apic->vcpu = vcpu; hrtimer_init(&apic->lapic_timer.timer, CLOCK_MONOTONIC, - HRTIMER_MODE_ABS); + HRTIMER_MODE_ABS_HARD); apic->lapic_timer.timer.function = apic_timer_fn; if (timer_advance_ns == -1) { apic->lapic_timer.timer_advance_ns = LAPIC_TIMER_ADVANCE_ADJUST_INIT; @@ -2487,7 +2487,7 @@ void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu) timer = &vcpu->arch.apic->lapic_timer.timer; if (hrtimer_cancel(timer)) - hrtimer_start_expires(timer, HRTIMER_MODE_ABS); + hrtimer_start_expires(timer, HRTIMER_MODE_ABS_HARD); } /*