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: Avi Kivity <avi@qumranet.com>

diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 4cb4430..634132a 100644 (file)
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -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);

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index be94f93..fd00f69 100644 (file)
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -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);
-               }
+               kvm_vcpu_kick(vcpu);
 
                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(

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3f3cb71..bf98d40 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -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 @@ again:
 
        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 @@ again:
        kvm_lapic_sync_from_vapic(vcpu);
 
        r = kvm_x86_ops->handle_exit(kvm_run, vcpu);
+out:
+       return r;
+}
 
-       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;
+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;
        }
 
-out:
-       up_read(&vcpu->kvm->slots_lock);
-       if (r > 0) {
-               kvm_resched(vcpu);
-               down_read(&vcpu->kvm->slots_lock);
-               goto again;
+       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;
+                       }
+                       if (signal_pending(current)) {
+                               r = -EINTR;
+                               kvm_run->exit_reason = KVM_EXIT_INTR;
+                               ++vcpu->stat.signal_exits;
+                       }
+                       if (need_resched()) {
+                               up_read(&vcpu->kvm->slots_lock);
+                               kvm_resched(vcpu);
+                               down_read(&vcpu->kvm->slots_lock);
+                       }
+               }
        }
 
+       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;
        }

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index a18aaad..4b03643 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -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;

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index de3b029..63e661b 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -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;