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 <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Gleb Natapov <[email protected]> Cc: [email protected] Cc: Ralf Baechle <[email protected]> Cc: [email protected] Cc: Sanjay Lal <[email protected]> --- v2: - Move kvm_mips_migrate_count() into kvm_tlb.c to fix a link error when KVM is built as a module, since kvm_tlb.c is built statically and cannot reference symbols in kvm_mips_emul.c. --- arch/mips/kvm/kvm_tlb.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/arch/mips/kvm/kvm_tlb.c b/arch/mips/kvm/kvm_tlb.c index 9d371ee0a755..d65999a9f8af 100644 --- a/arch/mips/kvm/kvm_tlb.c +++ b/arch/mips/kvm/kvm_tlb.c @@ -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) { -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
