3 files changed, 32 insertions, 14 deletions

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index a7cb93cb215..eb62761b768 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1810,6 +1810,14 @@ Valid flags are:
 
 #define KVM_PIT_SPEAKER_DUMMY     1 /* emulate speaker port stub */
 
+PIT timer interrupts may use a per-VM kernel thread for injection. If it
+exists, this thread will have a name of the following pattern:
+
+kvm-pit/<owner-process-pid>
+
+When running a guest with elevated priorities, the scheduling parameters of
+this thread may have to be adjusted accordingly.
+
 This IOCTL replaces the obsolete KVM_CREATE_PIT.
 
 
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);
         }
 }
diff --git a/arch/x86/kvm/i8254.h b/arch/x86/kvm/i8254.h
index 51a97426e79..fdf40425ea1 100644
--- a/arch/x86/kvm/i8254.h
+++ b/arch/x86/kvm/i8254.h
@@ -1,6 +1,8 @@
 #ifndef __I8254_H
 #define __I8254_H
 
+#include <linux/kthread.h>
+
 #include "iodev.h"
 
 struct kvm_kpit_channel_state {
@@ -39,8 +41,9 @@ struct kvm_pit {
         struct kvm_kpit_state pit_state;
         int irq_source_id;
         struct kvm_irq_mask_notifier mask_notifier;
-        struct workqueue_struct *wq;
-        struct work_struct expired;
+        struct kthread_worker worker;
+        struct task_struct *worker_task;
+        struct kthread_work expired;
 };
 
 #define KVM_PIT_BASE_ADDRESS        0x40