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MIPS: KVM: Migrate hrtimer to follow VCPU

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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: James 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: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
James Hogan 2014-05-29 10:16:34 +01:00 committed by Paolo Bonzini
parent c73c99b0df
commit 3a0ba77408
1 changed files with 23 additions and 0 deletions
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23
arch/mips/kvm/kvm_tlb.c
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@ -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) {