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authorJan Kiszka <jan.kiszka@siemens.com>2012-04-24 16:40:17 +0200
committerMarcelo Tosatti <mtosatti@redhat.com>2012-04-27 19:40:29 -0300
commitb6ddf05ff68d81a7c1736717faf492b70e9bf4f9 (patch)
treedbcf0f64e8bd0e420a498b6d074b5f0d1afc91ed /arch/x86/kvm/i8254.c
parent0589ff6c11d8128cf053c3ddc75b0f6d8b71c62b (diff)
KVM: x86: Run PIT work in own kthread
We can't run PIT IRQ injection work in the interrupt context of the host timer. This would allow the user to influence the handler complexity by asking for a broadcast to a large number of VCPUs. Therefore, this work was pushed into workqueue context in 9d244caf2e. However, this prevents prioritizing the PIT injection over other task as workqueues share kernel threads. This replaces the workqueue with a kthread worker and gives that thread a name in the format "kvm-pit/<owner-process-pid>". That allows to identify and adjust the kthread priority according to the VM process parameters. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'arch/x86/kvm/i8254.c')
-rw-r--r--arch/x86/kvm/i8254.c31
1 files changed, 19 insertions, 12 deletions
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index d68f99df690..adba28f88d1 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -34,7 +34,6 @@
#include <linux/kvm_host.h>
#include <linux/slab.h>
-#include <linux/workqueue.h>
#include "irq.h"
#include "i8254.h"
@@ -249,7 +248,7 @@ static void kvm_pit_ack_irq(struct kvm_irq_ack_notifier *kian)
/* in this case, we had multiple outstanding pit interrupts
* that we needed to inject. Reinject
*/
- queue_work(ps->pit->wq, &ps->pit->expired);
+ queue_kthread_work(&ps->pit->worker, &ps->pit->expired);
ps->irq_ack = 1;
spin_unlock(&ps->inject_lock);
}
@@ -270,7 +269,7 @@ void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu)
static void destroy_pit_timer(struct kvm_pit *pit)
{
hrtimer_cancel(&pit->pit_state.pit_timer.timer);
- cancel_work_sync(&pit->expired);
+ flush_kthread_work(&pit->expired);
}
static bool kpit_is_periodic(struct kvm_timer *ktimer)
@@ -284,7 +283,7 @@ static struct kvm_timer_ops kpit_ops = {
.is_periodic = kpit_is_periodic,
};
-static void pit_do_work(struct work_struct *work)
+static void pit_do_work(struct kthread_work *work)
{
struct kvm_pit *pit = container_of(work, struct kvm_pit, expired);
struct kvm *kvm = pit->kvm;
@@ -328,7 +327,7 @@ static enum hrtimer_restart pit_timer_fn(struct hrtimer *data)
if (ktimer->reinject || !atomic_read(&ktimer->pending)) {
atomic_inc(&ktimer->pending);
- queue_work(pt->wq, &pt->expired);
+ queue_kthread_work(&pt->worker, &pt->expired);
}
if (ktimer->t_ops->is_periodic(ktimer)) {
@@ -353,7 +352,7 @@ static void create_pit_timer(struct kvm *kvm, u32 val, int is_period)
/* TODO The new value only affected after the retriggered */
hrtimer_cancel(&pt->timer);
- cancel_work_sync(&ps->pit->expired);
+ flush_kthread_work(&ps->pit->expired);
pt->period = interval;
ps->is_periodic = is_period;
@@ -669,6 +668,8 @@ struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
{
struct kvm_pit *pit;
struct kvm_kpit_state *pit_state;
+ struct pid *pid;
+ pid_t pid_nr;
int ret;
pit = kzalloc(sizeof(struct kvm_pit), GFP_KERNEL);
@@ -685,14 +686,20 @@ struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
mutex_lock(&pit->pit_state.lock);
spin_lock_init(&pit->pit_state.inject_lock);
- pit->wq = create_singlethread_workqueue("kvm-pit-wq");
- if (!pit->wq) {
+ pid = get_pid(task_tgid(current));
+ pid_nr = pid_vnr(pid);
+ put_pid(pid);
+
+ init_kthread_worker(&pit->worker);
+ pit->worker_task = kthread_run(kthread_worker_fn, &pit->worker,
+ "kvm-pit/%d", pid_nr);
+ if (IS_ERR(pit->worker_task)) {
mutex_unlock(&pit->pit_state.lock);
kvm_free_irq_source_id(kvm, pit->irq_source_id);
kfree(pit);
return NULL;
}
- INIT_WORK(&pit->expired, pit_do_work);
+ init_kthread_work(&pit->expired, pit_do_work);
kvm->arch.vpit = pit;
pit->kvm = kvm;
@@ -736,7 +743,7 @@ fail:
kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier);
kvm_unregister_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier);
kvm_free_irq_source_id(kvm, pit->irq_source_id);
- destroy_workqueue(pit->wq);
+ kthread_stop(pit->worker_task);
kfree(pit);
return NULL;
}
@@ -756,10 +763,10 @@ void kvm_free_pit(struct kvm *kvm)
mutex_lock(&kvm->arch.vpit->pit_state.lock);
timer = &kvm->arch.vpit->pit_state.pit_timer.timer;
hrtimer_cancel(timer);
- cancel_work_sync(&kvm->arch.vpit->expired);
+ flush_kthread_work(&kvm->arch.vpit->expired);
+ kthread_stop(kvm->arch.vpit->worker_task);
kvm_free_irq_source_id(kvm, kvm->arch.vpit->irq_source_id);
mutex_unlock(&kvm->arch.vpit->pit_state.lock);
- destroy_workqueue(kvm->arch.vpit->wq);
kfree(kvm->arch.vpit);
}
}