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Commit d7690175 authored by Marcelo Tosatti's avatar Marcelo Tosatti Committed by Avi Kivity
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KVM: x86: do not execute halted vcpus 



Offline or uninitialized vcpu's can be executed if requested to perform
userspace work.

Follow Avi's suggestion to handle halted vcpu's in the main loop,
simplifying kvm_emulate_halt(). Introduce a new vcpu->requests bit to
indicate events that promote state from halted to running.

Also standardize vcpu wake sites.

Signed-off-by: Marcelo Tosatti <mtosatti <at> redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent a6a3034c

arch/x86/kvm/i8254.c

+2 −3
Original line number Diff line number Diff line
@@ -200,10 +200,9 @@ static int __pit_timer_fn(struct kvm_kpit_state *ps) 


	if (!atomic_inc_and_test(&pt->pending))

		set_bit(KVM_REQ_PENDING_TIMER, &vcpu0->requests);

	if (vcpu0 && waitqueue_active(&vcpu0->wq)) {

		vcpu0->arch.mp_state = KVM_MP_STATE_RUNNABLE;



	if (vcpu0 && waitqueue_active(&vcpu0->wq))

		wake_up_interruptible(&vcpu0->wq);

	}



	pt->timer.expires = ktime_add_ns(pt->timer.expires, pt->period);

	pt->scheduled = ktime_to_ns(pt->timer.expires);

arch/x86/kvm/lapic.c

+4 −12
Original line number Diff line number Diff line
@@ -339,13 +339,7 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode, 
		} else

			apic_clear_vector(vector, apic->regs + APIC_TMR);



		if (vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE)

		kvm_vcpu_kick(vcpu);

		else if (vcpu->arch.mp_state == KVM_MP_STATE_HALTED) {

			vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;

			if (waitqueue_active(&vcpu->wq))

				wake_up_interruptible(&vcpu->wq);

		}



		result = (orig_irr == 0);

		break;
@@ -384,8 +378,7 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode, 
		if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) {

			vcpu->arch.sipi_vector = vector;

			vcpu->arch.mp_state = KVM_MP_STATE_SIPI_RECEIVED;

			if (waitqueue_active(&vcpu->wq))

				wake_up_interruptible(&vcpu->wq);

			kvm_vcpu_kick(vcpu);

		}

		break;
@@ -950,10 +943,9 @@ static int __apic_timer_fn(struct kvm_lapic *apic) 


	if(!atomic_inc_and_test(&apic->timer.pending))

		set_bit(KVM_REQ_PENDING_TIMER, &apic->vcpu->requests);

	if (waitqueue_active(q)) {

		apic->vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;

	if (waitqueue_active(q))

		wake_up_interruptible(q);

	}



	if (apic_lvtt_period(apic)) {

		result = 1;

		apic->timer.dev.expires = ktime_add_ns(

arch/x86/kvm/x86.c

+55 −45
Original line number Diff line number Diff line
@@ -2798,11 +2798,6 @@ int kvm_emulate_halt(struct kvm_vcpu *vcpu) 
	KVMTRACE_0D(HLT, vcpu, handler);

	if (irqchip_in_kernel(vcpu->kvm)) {

		vcpu->arch.mp_state = KVM_MP_STATE_HALTED;

		up_read(&vcpu->kvm->slots_lock);

		kvm_vcpu_block(vcpu);

		down_read(&vcpu->kvm->slots_lock);

		if (vcpu->arch.mp_state != KVM_MP_STATE_RUNNABLE)

			return -EINTR;

		return 1;

	} else {

		vcpu->run->exit_reason = KVM_EXIT_HLT;
@@ -3097,24 +3092,10 @@ static void vapic_exit(struct kvm_vcpu *vcpu) 
	up_read(&vcpu->kvm->slots_lock);

}



static int __vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)

static int vcpu_enter_guest(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)

{

	int r;



	if (unlikely(vcpu->arch.mp_state == KVM_MP_STATE_SIPI_RECEIVED)) {

		pr_debug("vcpu %d received sipi with vector # %x\n",

		       vcpu->vcpu_id, vcpu->arch.sipi_vector);

		kvm_lapic_reset(vcpu);

		r = kvm_x86_ops->vcpu_reset(vcpu);

		if (r)

			return r;

		vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;

	}



	down_read(&vcpu->kvm->slots_lock);

	vapic_enter(vcpu);



again:

	if (vcpu->requests)

		if (test_and_clear_bit(KVM_REQ_MMU_RELOAD, &vcpu->requests))

			kvm_mmu_unload(vcpu);
@@ -3151,22 +3132,13 @@ static int __vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) 


	local_irq_disable();



	if (vcpu->requests || need_resched()) {

	if (vcpu->requests || need_resched() || signal_pending(current)) {

		local_irq_enable();

		preempt_enable();

		r = 1;

		goto out;

	}



	if (signal_pending(current)) {

		local_irq_enable();

		preempt_enable();

		r = -EINTR;

		kvm_run->exit_reason = KVM_EXIT_INTR;

		++vcpu->stat.signal_exits;

		goto out;

	}



	if (vcpu->guest_debug.enabled)

		kvm_x86_ops->guest_debug_pre(vcpu);
@@ -3227,26 +3199,63 @@ static int __vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) 
	kvm_lapic_sync_from_vapic(vcpu);



	r = kvm_x86_ops->handle_exit(kvm_run, vcpu);

out:

	return r;

}



static int __vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)

{

	int r;



	if (unlikely(vcpu->arch.mp_state == KVM_MP_STATE_SIPI_RECEIVED)) {

		printk("vcpu %d received sipi with vector # %x\n",

		       vcpu->vcpu_id, vcpu->arch.sipi_vector);

		kvm_lapic_reset(vcpu);

		r = kvm_x86_ops->vcpu_reset(vcpu);

		if (r)

			return r;

		vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;

	}



	down_read(&vcpu->kvm->slots_lock);

	vapic_enter(vcpu);



	r = 1;

	while (r > 0) {

		if (kvm_arch_vcpu_runnable(vcpu))

			r = vcpu_enter_guest(vcpu, kvm_run);

		else {

			up_read(&vcpu->kvm->slots_lock);

			kvm_vcpu_block(vcpu);

			down_read(&vcpu->kvm->slots_lock);

			if (test_and_clear_bit(KVM_REQ_UNHALT, &vcpu->requests))

				if (vcpu->arch.mp_state == KVM_MP_STATE_HALTED)

					vcpu->arch.mp_state =

							KVM_MP_STATE_RUNNABLE;

			if (vcpu->arch.mp_state != KVM_MP_STATE_RUNNABLE)

				r = -EINTR;

		}



		if (r > 0) {

			if (dm_request_for_irq_injection(vcpu, kvm_run)) {

				r = -EINTR;

				kvm_run->exit_reason = KVM_EXIT_INTR;

				++vcpu->stat.request_irq_exits;

			goto out;

			}

		if (!need_resched())

			goto again;

			if (signal_pending(current)) {

				r = -EINTR;

				kvm_run->exit_reason = KVM_EXIT_INTR;

				++vcpu->stat.signal_exits;

			}



out:

			if (need_resched()) {

				up_read(&vcpu->kvm->slots_lock);

	if (r > 0) {

				kvm_resched(vcpu);

				down_read(&vcpu->kvm->slots_lock);

		goto again;

			}

		}

	}



	up_read(&vcpu->kvm->slots_lock);

	post_kvm_run_save(vcpu, kvm_run);



	vapic_exit(vcpu);
@@ -3266,6 +3275,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) 


	if (unlikely(vcpu->arch.mp_state == KVM_MP_STATE_UNINITIALIZED)) {

		kvm_vcpu_block(vcpu);

		clear_bit(KVM_REQ_UNHALT, &vcpu->requests);

		r = -EAGAIN;

		goto out;

	}

include/linux/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ 
#define KVM_REQ_MMU_RELOAD         3

#define KVM_REQ_TRIPLE_FAULT       4

#define KVM_REQ_PENDING_TIMER      5

#define KVM_REQ_UNHALT             6



struct kvm_vcpu;

extern struct kmem_cache *kvm_vcpu_cache;

virt/kvm/kvm_main.c

+5 −5
Original line number Diff line number Diff line
@@ -980,12 +980,12 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu) 
	for (;;) {

		prepare_to_wait(&vcpu->wq, &wait, TASK_INTERRUPTIBLE);



		if (kvm_cpu_has_interrupt(vcpu))

			break;

		if (kvm_cpu_has_pending_timer(vcpu))

			break;

		if (kvm_arch_vcpu_runnable(vcpu))

		if (kvm_cpu_has_interrupt(vcpu) ||

		    kvm_cpu_has_pending_timer(vcpu) ||

		    kvm_arch_vcpu_runnable(vcpu)) {

			set_bit(KVM_REQ_UNHALT, &vcpu->requests);

			break;

		}

		if (signal_pending(current))

			break;