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authorJintack Lim <jintack@cs.columbia.edu>2017-02-03 10:20:06 -0500
committerMarc Zyngier <marc.zyngier@arm.com>2017-02-08 15:13:36 +0000
commitf242adaf0c7e8376e9f54ffd6ef088df84577893 (patch)
tree989465b4dd9ae7b9629580ad4b8f07d2136e455e
parentfb280e97576a91c01b2a1712dba31024748b3084 (diff)
KVM: arm/arm64: Set up a background timer for the physical timer emulation
Set a background timer for the EL1 physical timer emulation while VMs are running, so that VMs get the physical timer interrupts in a timely manner. Schedule the background timer on entry to the VM and cancel it on exit. This would not have any performance impact to the guest OSes that currently use the virtual timer since the physical timer is always not enabled. Signed-off-by: Jintack Lim <jintack@cs.columbia.edu> Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
-rw-r--r--virt/kvm/arm/arch_timer.c25
1 files changed, 24 insertions, 1 deletions
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index 0ea745290871..33257b560f74 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -229,6 +229,22 @@ static int kvm_timer_update_state(struct kvm_vcpu *vcpu)
return 0;
}
+/* Schedule the background timer for the emulated timer. */
+static void kvm_timer_emulate(struct kvm_vcpu *vcpu,
+ struct arch_timer_context *timer_ctx)
+{
+ struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+
+ if (kvm_timer_should_fire(timer_ctx))
+ return;
+
+ if (!kvm_timer_irq_can_fire(timer_ctx))
+ return;
+
+ /* The timer has not yet expired, schedule a background timer */
+ timer_arm(timer, kvm_timer_compute_delta(timer_ctx));
+}
+
/*
* Schedule the background timer before calling kvm_vcpu_block, so that this
* thread is removed from its waitqueue and made runnable when there's a timer
@@ -286,6 +302,9 @@ void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
if (kvm_timer_update_state(vcpu))
return;
+ /* Set the background timer for the physical timer emulation. */
+ kvm_timer_emulate(vcpu, vcpu_ptimer(vcpu));
+
/*
* If we enter the guest with the virtual input level to the VGIC
* asserted, then we have already told the VGIC what we need to, and
@@ -348,7 +367,11 @@ void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
{
struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
- BUG_ON(timer_is_armed(timer));
+ /*
+ * This is to cancel the background timer for the physical timer
+ * emulation if it is set.
+ */
+ timer_disarm(timer);
/*
* The guest could have modified the timer registers or the timer