[mirror_ubuntu-bionic-kernel.git] / virt / kvm / async_pf.c

/*
 * kvm asynchronous fault support
 *
 * Copyright 2010 Red Hat, Inc.
 *
 * Author:
 *      Gleb Natapov <gleb@redhat.com>
 *
 * This file is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#include <linux/kvm_host.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/mmu_context.h>

#include "async_pf.h"
#include <trace/events/kvm.h>

static inline void kvm_async_page_present_sync(struct kvm_vcpu *vcpu,
					       struct kvm_async_pf *work)
{
#ifdef CONFIG_KVM_ASYNC_PF_SYNC
	kvm_arch_async_page_present(vcpu, work);
#endif
}
static inline void kvm_async_page_present_async(struct kvm_vcpu *vcpu,
						struct kvm_async_pf *work)
{
#ifndef CONFIG_KVM_ASYNC_PF_SYNC
	kvm_arch_async_page_present(vcpu, work);
#endif
}

static struct kmem_cache *async_pf_cache;

int kvm_async_pf_init(void)
{
	async_pf_cache = KMEM_CACHE(kvm_async_pf, 0);

	if (!async_pf_cache)
		return -ENOMEM;

	return 0;
}

void kvm_async_pf_deinit(void)
{
	kmem_cache_destroy(async_pf_cache);
	async_pf_cache = NULL;
}

void kvm_async_pf_vcpu_init(struct kvm_vcpu *vcpu)
{
	INIT_LIST_HEAD(&vcpu->async_pf.done);
	INIT_LIST_HEAD(&vcpu->async_pf.queue);
	spin_lock_init(&vcpu->async_pf.lock);
}

static void async_pf_execute(struct work_struct *work)
{
	struct kvm_async_pf *apf =
		container_of(work, struct kvm_async_pf, work);
	struct mm_struct *mm = apf->mm;
	struct kvm_vcpu *vcpu = apf->vcpu;
	unsigned long addr = apf->addr;
	gva_t gva = apf->gva;

	might_sleep();

	/*
	 * This work is run asynchromously to the task which owns
	 * mm and might be done in another context, so we must
	 * use FOLL_REMOTE.
	 */
	__get_user_pages_unlocked(NULL, mm, addr, 1, NULL,
			FOLL_WRITE | FOLL_REMOTE);

	kvm_async_page_present_sync(vcpu, apf);

	spin_lock(&vcpu->async_pf.lock);
	list_add_tail(&apf->link, &vcpu->async_pf.done);
	spin_unlock(&vcpu->async_pf.lock);

	/*
	 * apf may be freed by kvm_check_async_pf_completion() after
	 * this point
	 */

	trace_kvm_async_pf_completed(addr, gva);

	/*
	 * This memory barrier pairs with prepare_to_wait's set_current_state()
	 */
	smp_mb();
	if (swait_active(&vcpu->wq))
		swake_up(&vcpu->wq);

	mmput(mm);
	kvm_put_kvm(vcpu->kvm);
}

void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
{
	/* cancel outstanding work queue item */
	while (!list_empty(&vcpu->async_pf.queue)) {
		struct kvm_async_pf *work =
			list_first_entry(&vcpu->async_pf.queue,
					 typeof(*work), queue);
		list_del(&work->queue);

#ifdef CONFIG_KVM_ASYNC_PF_SYNC
		flush_work(&work->work);
#else
		if (cancel_work_sync(&work->work)) {
			mmput(work->mm);
			kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */
			kmem_cache_free(async_pf_cache, work);
		}
#endif
	}

	spin_lock(&vcpu->async_pf.lock);
	while (!list_empty(&vcpu->async_pf.done)) {
		struct kvm_async_pf *work =
			list_first_entry(&vcpu->async_pf.done,
					 typeof(*work), link);
		list_del(&work->link);
		kmem_cache_free(async_pf_cache, work);
	}
	spin_unlock(&vcpu->async_pf.lock);

	vcpu->async_pf.queued = 0;
}

void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
{
	struct kvm_async_pf *work;

	while (!list_empty_careful(&vcpu->async_pf.done) &&
	      kvm_arch_can_inject_async_page_present(vcpu)) {
		spin_lock(&vcpu->async_pf.lock);
		work = list_first_entry(&vcpu->async_pf.done, typeof(*work),
					      link);
		list_del(&work->link);
		spin_unlock(&vcpu->async_pf.lock);

		kvm_arch_async_page_ready(vcpu, work);
		kvm_async_page_present_async(vcpu, work);

		list_del(&work->queue);
		vcpu->async_pf.queued--;
		kmem_cache_free(async_pf_cache, work);
	}
}

int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, unsigned long hva,
		       struct kvm_arch_async_pf *arch)
{
	struct kvm_async_pf *work;

	if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU)
		return 0;

	/* setup delayed work */

	/*
	 * do alloc nowait since if we are going to sleep anyway we
	 * may as well sleep faulting in page
	 */
	work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT | __GFP_NOWARN);
	if (!work)
		return 0;

	work->wakeup_all = false;
	work->vcpu = vcpu;
	work->gva = gva;
	work->addr = hva;
	work->arch = *arch;
	work->mm = current->mm;
	atomic_inc(&work->mm->mm_users);
	kvm_get_kvm(work->vcpu->kvm);

	/* this can't really happen otherwise gfn_to_pfn_async
	   would succeed */
	if (unlikely(kvm_is_error_hva(work->addr)))
		goto retry_sync;

	INIT_WORK(&work->work, async_pf_execute);
	if (!schedule_work(&work->work))
		goto retry_sync;

	list_add_tail(&work->queue, &vcpu->async_pf.queue);
	vcpu->async_pf.queued++;
	kvm_arch_async_page_not_present(vcpu, work);
	return 1;
retry_sync:
	kvm_put_kvm(work->vcpu->kvm);
	mmput(work->mm);
	kmem_cache_free(async_pf_cache, work);
	return 0;
}

int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
{
	struct kvm_async_pf *work;

	if (!list_empty_careful(&vcpu->async_pf.done))
		return 0;

	work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
	if (!work)
		return -ENOMEM;

	work->wakeup_all = true;
	INIT_LIST_HEAD(&work->queue); /* for list_del to work */

	spin_lock(&vcpu->async_pf.lock);
	list_add_tail(&work->link, &vcpu->async_pf.done);
	spin_unlock(&vcpu->async_pf.lock);

	vcpu->async_pf.queued++;
	return 0;
}
Commit	Line	Data
af585b92 GN	1	/*
	2	* kvm asynchronous fault support
	3	*
	4	* Copyright 2010 Red Hat, Inc.
	5	*
	6	* Author:
	7	* Gleb Natapov <gleb@redhat.com>
	8	*
	9	* This file is free software; you can redistribute it and/or modify
	10	* it under the terms of version 2 of the GNU General Public License
	11	* as published by the Free Software Foundation.
	12	*
	13	* This program is distributed in the hope that it will be useful,
	14	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	15	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	16	* GNU General Public License for more details.
	17	*
	18	* You should have received a copy of the GNU General Public License
	19	* along with this program; if not, write to the Free Software Foundation,
	20	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
	21	*/
	22
	23	#include <linux/kvm_host.h>
	24	#include <linux/slab.h>
	25	#include <linux/module.h>
	26	#include <linux/mmu_context.h>
	27
	28	#include "async_pf.h"
	29	#include <trace/events/kvm.h>
	30
e0ead41a DD	31	static inline void kvm_async_page_present_sync(struct kvm_vcpu *vcpu,
	32	struct kvm_async_pf *work)
	33	{
	34	#ifdef CONFIG_KVM_ASYNC_PF_SYNC
	35	kvm_arch_async_page_present(vcpu, work);
	36	#endif
	37	}
	38	static inline void kvm_async_page_present_async(struct kvm_vcpu *vcpu,
	39	struct kvm_async_pf *work)
	40	{
	41	#ifndef CONFIG_KVM_ASYNC_PF_SYNC
	42	kvm_arch_async_page_present(vcpu, work);
	43	#endif
	44	}
	45
af585b92 GN	46	static struct kmem_cache *async_pf_cache;
	47
	48	int kvm_async_pf_init(void)
	49	{
	50	async_pf_cache = KMEM_CACHE(kvm_async_pf, 0);
	51
	52	if (!async_pf_cache)
	53	return -ENOMEM;
	54
	55	return 0;
	56	}
	57
	58	void kvm_async_pf_deinit(void)
	59	{
4f52696a	60	kmem_cache_destroy(async_pf_cache);
af585b92 GN	61	async_pf_cache = NULL;
	62	}
	63
	64	void kvm_async_pf_vcpu_init(struct kvm_vcpu *vcpu)
	65	{
	66	INIT_LIST_HEAD(&vcpu->async_pf.done);
	67	INIT_LIST_HEAD(&vcpu->async_pf.queue);
	68	spin_lock_init(&vcpu->async_pf.lock);
	69	}
	70
	71	static void async_pf_execute(struct work_struct *work)
	72	{
af585b92 GN	73	struct kvm_async_pf *apf =
	74	container_of(work, struct kvm_async_pf, work);
	75	struct mm_struct *mm = apf->mm;
	76	struct kvm_vcpu *vcpu = apf->vcpu;
	77	unsigned long addr = apf->addr;
	78	gva_t gva = apf->gva;
	79
	80	might_sleep();
	81
1e987790 DH	82	/*
	83	* This work is run asynchromously to the task which owns
	84	* mm and might be done in another context, so we must
	85	* use FOLL_REMOTE.
	86	*/
d4944b0e LS	87	__get_user_pages_unlocked(NULL, mm, addr, 1, NULL,
d4944b0e LS	88	FOLL_WRITE \| FOLL_REMOTE);
1e987790	89
e0ead41a	90	kvm_async_page_present_sync(vcpu, apf);
af585b92 GN	91
	92	spin_lock(&vcpu->async_pf.lock);
	93	list_add_tail(&apf->link, &vcpu->async_pf.done);
af585b92 GN	94	spin_unlock(&vcpu->async_pf.lock);
	95
	96	/*
	97	* apf may be freed by kvm_check_async_pf_completion() after
	98	* this point
	99	*/
	100
f2e10669	101	trace_kvm_async_pf_completed(addr, gva);
af585b92	102
6003a420 KT	103	/*
	104	* This memory barrier pairs with prepare_to_wait's set_current_state()
	105	*/
	106	smp_mb();
8577370f MT	107	if (swait_active(&vcpu->wq))
8577370f MT	108	swake_up(&vcpu->wq);
af585b92	109
41c22f62	110	mmput(mm);
af585b92 GN	111	kvm_put_kvm(vcpu->kvm);
	112	}
	113
	114	void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
	115	{
	116	/* cancel outstanding work queue item */
	117	while (!list_empty(&vcpu->async_pf.queue)) {
	118	struct kvm_async_pf *work =
433da860 GT	119	list_first_entry(&vcpu->async_pf.queue,
433da860 GT	120	typeof(*work), queue);
af585b92	121	list_del(&work->queue);
9f2ceda4 DD	122
	123	#ifdef CONFIG_KVM_ASYNC_PF_SYNC
	124	flush_work(&work->work);
	125	#else
98fda169	126	if (cancel_work_sync(&work->work)) {
41c22f62	127	mmput(work->mm);
28b441e2	128	kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */
af585b92	129	kmem_cache_free(async_pf_cache, work);
28b441e2	130	}
9f2ceda4	131	#endif
af585b92 GN	132	}
	133
	134	spin_lock(&vcpu->async_pf.lock);
	135	while (!list_empty(&vcpu->async_pf.done)) {
	136	struct kvm_async_pf *work =
433da860 GT	137	list_first_entry(&vcpu->async_pf.done,
433da860 GT	138	typeof(*work), link);
af585b92	139	list_del(&work->link);
af585b92 GN	140	kmem_cache_free(async_pf_cache, work);
	141	}
	142	spin_unlock(&vcpu->async_pf.lock);
	143
	144	vcpu->async_pf.queued = 0;
	145	}
	146
	147	void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
	148	{
	149	struct kvm_async_pf *work;
	150
15096ffc XG	151	while (!list_empty_careful(&vcpu->async_pf.done) &&
	152	kvm_arch_can_inject_async_page_present(vcpu)) {
	153	spin_lock(&vcpu->async_pf.lock);
	154	work = list_first_entry(&vcpu->async_pf.done, typeof(*work),
	155	link);
	156	list_del(&work->link);
	157	spin_unlock(&vcpu->async_pf.lock);
af585b92	158
f2e10669	159	kvm_arch_async_page_ready(vcpu, work);
1179ba53	160	kvm_async_page_present_async(vcpu, work);
af585b92	161
15096ffc XG	162	list_del(&work->queue);
15096ffc XG	163	vcpu->async_pf.queued--;
15096ffc XG	164	kmem_cache_free(async_pf_cache, work);
15096ffc XG	165	}
af585b92 GN	166	}
af585b92 GN	167
e0ead41a	168	int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, unsigned long hva,
af585b92 GN	169	struct kvm_arch_async_pf *arch)
	170	{
	171	struct kvm_async_pf *work;
	172
	173	if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU)
	174	return 0;
	175
	176	/* setup delayed work */
	177
	178	/*
	179	* do alloc nowait since if we are going to sleep anyway we
	180	* may as well sleep faulting in page
	181	*/
d7444794	182	work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT \| __GFP_NOWARN);
af585b92 GN	183	if (!work)
	184	return 0;
	185
f2e10669	186	work->wakeup_all = false;
af585b92 GN	187	work->vcpu = vcpu;
af585b92 GN	188	work->gva = gva;
e0ead41a	189	work->addr = hva;
af585b92 GN	190	work->arch = *arch;
af585b92 GN	191	work->mm = current->mm;
41c22f62	192	atomic_inc(&work->mm->mm_users);
af585b92 GN	193	kvm_get_kvm(work->vcpu->kvm);
	194
	195	/* this can't really happen otherwise gfn_to_pfn_async
	196	would succeed */
	197	if (unlikely(kvm_is_error_hva(work->addr)))
	198	goto retry_sync;
	199
	200	INIT_WORK(&work->work, async_pf_execute);
	201	if (!schedule_work(&work->work))
	202	goto retry_sync;
	203
	204	list_add_tail(&work->queue, &vcpu->async_pf.queue);
	205	vcpu->async_pf.queued++;
	206	kvm_arch_async_page_not_present(vcpu, work);
	207	return 1;
	208	retry_sync:
	209	kvm_put_kvm(work->vcpu->kvm);
41c22f62	210	mmput(work->mm);
af585b92 GN	211	kmem_cache_free(async_pf_cache, work);
	212	return 0;
	213	}
344d9588 GN	214
	215	int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
	216	{
	217	struct kvm_async_pf *work;
	218
64f638c7	219	if (!list_empty_careful(&vcpu->async_pf.done))
344d9588 GN	220	return 0;
	221
	222	work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
	223	if (!work)
	224	return -ENOMEM;
	225
f2e10669	226	work->wakeup_all = true;
344d9588 GN	227	INIT_LIST_HEAD(&work->queue); /* for list_del to work */
344d9588 GN	228
64f638c7	229	spin_lock(&vcpu->async_pf.lock);
344d9588	230	list_add_tail(&work->link, &vcpu->async_pf.done);
64f638c7 XG	231	spin_unlock(&vcpu->async_pf.lock);
64f638c7 XG	232
344d9588 GN	233	vcpu->async_pf.queued++;
	234	return 0;
	235	}