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/*
* 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 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)
{
if (async_pf_cache)
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 page *page = NULL;
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();
use_mm(mm);
down_read(&mm->mmap_sem);
get_user_pages(current, mm, addr, 1, 1, 0, &page, NULL);
up_read(&mm->mmap_sem);
unuse_mm(mm);
spin_lock(&vcpu->async_pf.lock);
list_add_tail(&apf->link, &vcpu->async_pf.done);
apf->page = page;
apf->done = true;
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, page, gva);
if (waitqueue_active(&vcpu->wq))
wake_up_interruptible(&vcpu->wq);
mmdrop(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_entry(vcpu->async_pf.queue.next,
typeof(*work), queue);
cancel_work_sync(&work->work);
list_del(&work->queue);
if (!work->done) /* work was canceled */
kmem_cache_free(async_pf_cache, work);
}
spin_lock(&vcpu->async_pf.lock);
while (!list_empty(&vcpu->async_pf.done)) {
struct kvm_async_pf *work =
list_entry(vcpu->async_pf.done.next,
typeof(*work), link);
list_del(&work->link);
if (work->page)
put_page(work->page);
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;
if (list_empty_careful(&vcpu->async_pf.done))
return;
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);
if (work->page)
kvm_arch_async_page_ready(vcpu, work);
kvm_arch_async_page_present(vcpu, work);
list_del(&work->queue);
vcpu->async_pf.queued--;
if (work->page)
put_page(work->page);
kmem_cache_free(async_pf_cache, work);
}
int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn,
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);
if (!work)
return 0;
work->page = NULL;
work->done = false;
work->vcpu = vcpu;
work->gva = gva;
work->addr = gfn_to_hva(vcpu->kvm, gfn);
work->arch = *arch;
work->mm = current->mm;
atomic_inc(&work->mm->mm_count);
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);
mmdrop(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(&vcpu->async_pf.done))
return 0;
work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
if (!work)
return -ENOMEM;
work->page = bad_page;
get_page(bad_page);
INIT_LIST_HEAD(&work->queue); /* for list_del to work */
list_add_tail(&work->link, &vcpu->async_pf.done);
vcpu->async_pf.queued++;
return 0;
}
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