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Commit 8c35f237 authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: Route irq 0 to vcpu 0 exclusively 



Some Linux versions allow the timer interrupt to be processed by more than
one cpu, leading to hangs due to tsc instability.  Work around the issue
by only disaptching the interrupt to vcpu 0.

Problem analyzed (and patch tested) by Sheng Yang.

Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 0b975a3c

virt/kvm/ioapic.c

+8 −0
Original line number Diff line number Diff line
@@ -211,6 +211,10 @@ static void ioapic_deliver(struct kvm_ioapic *ioapic, int irq) 
	case IOAPIC_LOWEST_PRIORITY:

		vcpu = kvm_get_lowest_prio_vcpu(ioapic->kvm, vector,

				deliver_bitmask);

#ifdef CONFIG_X86

		if (irq == 0)

			vcpu = ioapic->kvm->vcpus[0];

#endif

		if (vcpu != NULL)

			ioapic_inj_irq(ioapic, vcpu, vector,

				       trig_mode, delivery_mode);
@@ -220,6 +224,10 @@ static void ioapic_deliver(struct kvm_ioapic *ioapic, int irq) 
				     deliver_bitmask, vector, IOAPIC_LOWEST_PRIORITY);

		break;

	case IOAPIC_FIXED:

#ifdef CONFIG_X86

		if (irq == 0)

			deliver_bitmask = 1;

#endif

		for (vcpu_id = 0; deliver_bitmask != 0; vcpu_id++) {

			if (!(deliver_bitmask & (1 << vcpu_id)))

				continue;