[RFC PATCH 1/3] kvm: keep track of which task is running a KVM vcpu

Rik van Riel
2010-12-02T19:45:45Z

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>

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 5fbdb55..cb73a73 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -79,6 +79,7 @@ struct kvm_vcpu {
#endif
int vcpu_id;
struct mutex mutex;
+ struct task_struct *task;
int cpu;
struct kvm_run *run;
unsigned long requests;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 050577a..2bffa47 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -741,6 +741,7 @@ void vcpu_load(struct kvm_vcpu *vcpu)
int cpu;

mutex_lock(&vcpu->mutex);
+ vcpu->task = current;
cpu = get_cpu();
preempt_notifier_register(&vcpu->preempt_notifier);
kvm_arch_vcpu_load(vcpu, cpu);
@@ -749,6 +750,7 @@ void vcpu_load(struct kvm_vcpu *vcpu)

void vcpu_put(struct kvm_vcpu *vcpu)
{
+ vcpu->task = NULL;
preempt_disable();
kvm_arch_vcpu_put(vcpu);
preempt_notifier_unregister(&vcpu->preempt_notifier);

--
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