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Commit 3a0ba774 authored by James Hogan's avatar James Hogan Committed by Paolo Bonzini
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MIPS: KVM: Migrate hrtimer to follow VCPU 



When a VCPU is scheduled in on a different CPU, refresh the hrtimer used
for emulating count/compare so that it gets migrated to the same CPU.

This should prevent a timer interrupt occurring on a different CPU to
where the guest it relates to is running, which would cause the guest
timer interrupt not to be delivered until after the next guest exit.

Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: kvm@vger.kernel.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: Sanjay Lal <sanjayl@kymasys.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent c73c99b0

arch/mips/kvm/kvm_tlb.c

+23 −0
Original line number Diff line number Diff line
@@ -656,6 +656,23 @@ void kvm_local_flush_tlb_all(void) 
	local_irq_restore(flags);

}



/**

 * kvm_mips_migrate_count() - Migrate timer.

 * @vcpu:	Virtual CPU.

 *

 * Migrate CP0_Count hrtimer to the current CPU by cancelling and restarting it

 * if it was running prior to being cancelled.

 *

 * Must be called when the VCPU is migrated to a different CPU to ensure that

 * timer expiry during guest execution interrupts the guest and causes the

 * interrupt to be delivered in a timely manner.

 */

static void kvm_mips_migrate_count(struct kvm_vcpu *vcpu)

{

	if (hrtimer_cancel(&vcpu->arch.comparecount_timer))

		hrtimer_restart(&vcpu->arch.comparecount_timer);

}



/* Restore ASID once we are scheduled back after preemption */

void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)

{
@@ -691,6 +708,12 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) 
	if (vcpu->arch.last_sched_cpu != cpu) {

		kvm_info("[%d->%d]KVM VCPU[%d] switch\n",

			 vcpu->arch.last_sched_cpu, cpu, vcpu->vcpu_id);

		/*

		 * Migrate the timer interrupt to the current CPU so that it

		 * always interrupts the guest and synchronously triggers a

		 * guest timer interrupt.

		 */

		kvm_mips_migrate_count(vcpu);

	}



	if (!newasid) {