KVM: Use the scheduler preemption notifiers to make kvm preemptible

[mirror_ubuntu-artful-kernel.git] / drivers / kvm / kvm_main.c

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 20947462f40185dc9aef08b6d48c89e1776d74cf..6035e6d3541722260e43d23afd749618cc65394a 100644 (file)
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -54,6 +54,8 @@ static cpumask_t cpus_hardware_enabled;
 
 struct kvm_arch_ops *kvm_arch_ops;
 
+static __read_mostly struct preempt_ops kvm_preempt_ops;
+
 #define STAT_OFFSET(x) offsetof(struct kvm_vcpu, stat.x)
 
 static struct kvm_stats_debugfs_item {
@@ -239,13 +241,21 @@ EXPORT_SYMBOL_GPL(kvm_put_guest_fpu);
  */
 static void vcpu_load(struct kvm_vcpu *vcpu)
 {
+       int cpu;
+
        mutex_lock(&vcpu->mutex);
-       kvm_arch_ops->vcpu_load(vcpu);
+       cpu = get_cpu();
+       preempt_notifier_register(&vcpu->preempt_notifier);
+       kvm_arch_ops->vcpu_load(vcpu, cpu);
+       put_cpu();
 }
 
 static void vcpu_put(struct kvm_vcpu *vcpu)
 {
+       preempt_disable();
        kvm_arch_ops->vcpu_put(vcpu);
+       preempt_notifier_unregister(&vcpu->preempt_notifier);
+       preempt_enable();
        mutex_unlock(&vcpu->mutex);
 }
 
@@ -1672,9 +1682,7 @@ void kvm_resched(struct kvm_vcpu *vcpu)
 {
        if (!need_resched())
                return;
-       vcpu_put(vcpu);
        cond_resched();
-       vcpu_load(vcpu);
 }
 EXPORT_SYMBOL_GPL(kvm_resched);
 
@@ -1722,11 +1730,9 @@ static int pio_copy_data(struct kvm_vcpu *vcpu)
        unsigned bytes;
        int nr_pages = vcpu->pio.guest_pages[1] ? 2 : 1;
 
-       kvm_arch_ops->vcpu_put(vcpu);
        q = vmap(vcpu->pio.guest_pages, nr_pages, VM_READ|VM_WRITE,
                 PAGE_KERNEL);
        if (!q) {
-               kvm_arch_ops->vcpu_load(vcpu);
                free_pio_guest_pages(vcpu);
                return -ENOMEM;
        }
@@ -1738,7 +1744,6 @@ static int pio_copy_data(struct kvm_vcpu *vcpu)
                memcpy(p, q, bytes);
        q -= vcpu->pio.guest_page_offset;
        vunmap(q);
-       kvm_arch_ops->vcpu_load(vcpu);
        free_pio_guest_pages(vcpu);
        return 0;
 }
@@ -2413,6 +2418,8 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n)
        if (IS_ERR(vcpu))
                return PTR_ERR(vcpu);
 
+       preempt_notifier_init(&vcpu->preempt_notifier, &kvm_preempt_ops);
+
        vcpu_load(vcpu);
        r = kvm_mmu_setup(vcpu);
        vcpu_put(vcpu);
@@ -3145,6 +3152,27 @@ static struct sys_device kvm_sysdev = {
 
 hpa_t bad_page_address;
 
+static inline
+struct kvm_vcpu *preempt_notifier_to_vcpu(struct preempt_notifier *pn)
+{
+       return container_of(pn, struct kvm_vcpu, preempt_notifier);
+}
+
+static void kvm_sched_in(struct preempt_notifier *pn, int cpu)
+{
+       struct kvm_vcpu *vcpu = preempt_notifier_to_vcpu(pn);
+
+       kvm_arch_ops->vcpu_load(vcpu, cpu);
+}
+
+static void kvm_sched_out(struct preempt_notifier *pn,
+                         struct task_struct *next)
+{
+       struct kvm_vcpu *vcpu = preempt_notifier_to_vcpu(pn);
+
+       kvm_arch_ops->vcpu_put(vcpu);
+}
+
 int kvm_init_arch(struct kvm_arch_ops *ops, struct module *module)
 {
        int r;
@@ -3191,6 +3219,9 @@ int kvm_init_arch(struct kvm_arch_ops *ops, struct module *module)
                goto out_free;
        }
 
+       kvm_preempt_ops.sched_in = kvm_sched_in;
+       kvm_preempt_ops.sched_out = kvm_sched_out;
+
        return r;
 
 out_free: