diff options
author | Christoffer Dall <christoffer.dall@arm.com> | 2018-11-26 20:21:22 +0300 |
---|---|---|
committer | Marc Zyngier <marc.zyngier@arm.com> | 2019-02-20 00:05:36 +0300 |
commit | accb99bcd0ca6d3ee412557b0c3f583a3abc0eb6 (patch) | |
tree | e997f4ed8b196b597a92bc89b22f00b70e78eee0 /virt | |
parent | e329fb75d519e3dc3eb11b22d5bb846516be3521 (diff) | |
download | linux-accb99bcd0ca6d3ee412557b0c3f583a3abc0eb6.tar.xz |
KVM: arm/arm64: Simplify bg_timer programming
Instead of calling into kvm_timer_[un]schedule from the main kvm
blocking path, test if the VCPU is on the wait queue from the load/put
path and perform the background timer setup/cancel in this path.
This has the distinct advantage that we no longer race between load/put
and schedule/unschedule and programming and canceling of the bg_timer
always happens when the timer state is not loaded.
Note that we must now remove the checks in kvm_timer_blocking that do
not schedule a background timer if one of the timers can fire, because
we no longer have a guarantee that kvm_vcpu_check_block() will be called
before kvm_timer_blocking.
Reported-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Diffstat (limited to 'virt')
-rw-r--r-- | virt/kvm/arm/arch_timer.c | 35 | ||||
-rw-r--r-- | virt/kvm/arm/arm.c | 2 |
2 files changed, 14 insertions, 23 deletions
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index b07ac4614e1c..4986028d9829 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -349,22 +349,12 @@ out: * thread is removed from its waitqueue and made runnable when there's a timer * interrupt to handle. */ -void kvm_timer_schedule(struct kvm_vcpu *vcpu) +static void kvm_timer_blocking(struct kvm_vcpu *vcpu) { struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); struct arch_timer_context *ptimer = vcpu_ptimer(vcpu); - vtimer_save_state(vcpu); - - /* - * No need to schedule a background timer if any guest timer has - * already expired, because kvm_vcpu_block will return before putting - * the thread to sleep. - */ - if (kvm_timer_should_fire(vtimer) || kvm_timer_should_fire(ptimer)) - return; - /* * If both timers are not capable of raising interrupts (disabled or * masked), then there's no more work for us to do. @@ -373,12 +363,19 @@ void kvm_timer_schedule(struct kvm_vcpu *vcpu) return; /* - * The guest timers have not yet expired, schedule a background timer. + * At least one guest time will expire. Schedule a background timer. * Set the earliest expiration time among the guest timers. */ soft_timer_start(&timer->bg_timer, kvm_timer_earliest_exp(vcpu)); } +static void kvm_timer_unblocking(struct kvm_vcpu *vcpu) +{ + struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; + + soft_timer_cancel(&timer->bg_timer); +} + static void vtimer_restore_state(struct kvm_vcpu *vcpu) { struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; @@ -401,15 +398,6 @@ out: local_irq_restore(flags); } -void kvm_timer_unschedule(struct kvm_vcpu *vcpu) -{ - struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; - - vtimer_restore_state(vcpu); - - soft_timer_cancel(&timer->bg_timer); -} - static void set_cntvoff(u64 cntvoff) { u32 low = lower_32_bits(cntvoff); @@ -485,6 +473,8 @@ void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu) /* Set the background timer for the physical timer emulation. */ phys_timer_emulate(vcpu); + kvm_timer_unblocking(vcpu); + /* If the timer fired while we weren't running, inject it now */ if (kvm_timer_should_fire(ptimer) != ptimer->irq.level) kvm_timer_update_irq(vcpu, !ptimer->irq.level, ptimer); @@ -527,6 +517,9 @@ void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu) */ soft_timer_cancel(&timer->phys_timer); + if (swait_active(kvm_arch_vcpu_wq(vcpu))) + kvm_timer_blocking(vcpu); + /* * The kernel may decide to run userspace after calling vcpu_put, so * we reset cntvoff to 0 to ensure a consistent read between user diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index b77db673bb03..9fbdb9e1c51f 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -335,13 +335,11 @@ int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu) void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) { - kvm_timer_schedule(vcpu); kvm_vgic_v4_enable_doorbell(vcpu); } void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) { - kvm_timer_unschedule(vcpu); kvm_vgic_v4_disable_doorbell(vcpu); } |