KVM: keep track of which task is running a KVM vcpu
Keep track of which task is running a KVM vcpu. This helps us
figure out later what task to wake up if we want to boost a
vcpu that got preempted.
Unfortunately there are no guarantees that the same task
always keeps the same vcpu, so we can only track the task
across a single "run" of the vcpu.
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 002fe0b..bc8bfd1 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -137,6 +137,14 @@
int cpu;
mutex_lock(&vcpu->mutex);
+ if (unlikely(vcpu->pid != current->pids[PIDTYPE_PID].pid)) {
+ /* The thread running this VCPU changed. */
+ struct pid *oldpid = vcpu->pid;
+ struct pid *newpid = get_task_pid(current, PIDTYPE_PID);
+ rcu_assign_pointer(vcpu->pid, newpid);
+ synchronize_rcu();
+ put_pid(oldpid);
+ }
cpu = get_cpu();
preempt_notifier_register(&vcpu->preempt_notifier);
kvm_arch_vcpu_load(vcpu, cpu);
@@ -212,6 +220,7 @@
vcpu->cpu = -1;
vcpu->kvm = kvm;
vcpu->vcpu_id = id;
+ vcpu->pid = NULL;
init_waitqueue_head(&vcpu->wq);
kvm_async_pf_vcpu_init(vcpu);
@@ -236,6 +245,7 @@
void kvm_vcpu_uninit(struct kvm_vcpu *vcpu)
{
+ put_pid(vcpu->pid);
kvm_arch_vcpu_uninit(vcpu);
free_page((unsigned long)vcpu->run);
}