From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754230Ab2DPS0n (ORCPT ); Mon, 16 Apr 2012 14:26:43 -0400 Received: from david.siemens.de ([192.35.17.14]:16401 "EHLO david.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750823Ab2DPS0l (ORCPT ); Mon, 16 Apr 2012 14:26:41 -0400 Message-ID: <4F8C645C.7010302@siemens.com> Date: Mon, 16 Apr 2012 20:26:36 +0200 From: Jan Kiszka User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 MIME-Version: 1.0 To: Avi Kivity , Marcelo Tosatti CC: kvm , Linux Kernel Mailing List Subject: [PATCH] KVM: x86: Run PIT work in own kthread Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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/". That allows to identify and adjust the kthread priority according to the VM process parameters. Signed-off-by: Jan Kiszka --- arch/x86/kvm/i8254.c | 31 +++++++++++++++++++------------ arch/x86/kvm/i8254.h | 7 +++++-- 2 files changed, 24 insertions(+), 14 deletions(-) diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c index d68f99d..adba28f 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -34,7 +34,6 @@ #include #include -#include #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 51a9742..fdf4042 100644 --- a/arch/x86/kvm/i8254.h +++ b/arch/x86/kvm/i8254.h @@ -1,6 +1,8 @@ #ifndef __I8254_H #define __I8254_H +#include + #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 -- 1.7.3.4