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![Wei Yang](/assets/img/avatar_default.png)
Signed-off-by: Wei Yang <richard.weiyang@gmail.com> [Preserved the iff and a probably intentional weird bracket notation. Also dropped the style change to make a single-purpose patch. - Radim] Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
247 lines
5.8 KiB
C
247 lines
5.8 KiB
C
/*
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* kvm asynchronous fault support
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*
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* Copyright 2010 Red Hat, Inc.
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*
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* Author:
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* Gleb Natapov <gleb@redhat.com>
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*
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* This file is free software; you can redistribute it and/or modify
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* it under the terms of version 2 of the GNU General Public License
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include <linux/kvm_host.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/mmu_context.h>
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#include <linux/sched/mm.h>
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#include "async_pf.h"
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#include <trace/events/kvm.h>
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static inline void kvm_async_page_present_sync(struct kvm_vcpu *vcpu,
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struct kvm_async_pf *work)
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{
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#ifdef CONFIG_KVM_ASYNC_PF_SYNC
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kvm_arch_async_page_present(vcpu, work);
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#endif
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}
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static inline void kvm_async_page_present_async(struct kvm_vcpu *vcpu,
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struct kvm_async_pf *work)
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{
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#ifndef CONFIG_KVM_ASYNC_PF_SYNC
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kvm_arch_async_page_present(vcpu, work);
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#endif
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}
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static struct kmem_cache *async_pf_cache;
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int kvm_async_pf_init(void)
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{
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async_pf_cache = KMEM_CACHE(kvm_async_pf, 0);
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if (!async_pf_cache)
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return -ENOMEM;
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return 0;
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}
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void kvm_async_pf_deinit(void)
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{
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kmem_cache_destroy(async_pf_cache);
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async_pf_cache = NULL;
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}
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void kvm_async_pf_vcpu_init(struct kvm_vcpu *vcpu)
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{
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INIT_LIST_HEAD(&vcpu->async_pf.done);
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INIT_LIST_HEAD(&vcpu->async_pf.queue);
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spin_lock_init(&vcpu->async_pf.lock);
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}
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static void async_pf_execute(struct work_struct *work)
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{
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struct kvm_async_pf *apf =
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container_of(work, struct kvm_async_pf, work);
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struct mm_struct *mm = apf->mm;
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struct kvm_vcpu *vcpu = apf->vcpu;
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unsigned long addr = apf->addr;
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gva_t gva = apf->gva;
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int locked = 1;
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might_sleep();
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/*
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* This work is run asynchronously to the task which owns
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* mm and might be done in another context, so we must
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* access remotely.
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*/
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down_read(&mm->mmap_sem);
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get_user_pages_remote(NULL, mm, addr, 1, FOLL_WRITE, NULL, NULL,
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&locked);
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if (locked)
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up_read(&mm->mmap_sem);
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kvm_async_page_present_sync(vcpu, apf);
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spin_lock(&vcpu->async_pf.lock);
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list_add_tail(&apf->link, &vcpu->async_pf.done);
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apf->vcpu = NULL;
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spin_unlock(&vcpu->async_pf.lock);
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/*
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* apf may be freed by kvm_check_async_pf_completion() after
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* this point
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*/
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trace_kvm_async_pf_completed(addr, gva);
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if (swq_has_sleeper(&vcpu->wq))
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swake_up_one(&vcpu->wq);
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mmput(mm);
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kvm_put_kvm(vcpu->kvm);
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}
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void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
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{
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spin_lock(&vcpu->async_pf.lock);
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/* cancel outstanding work queue item */
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while (!list_empty(&vcpu->async_pf.queue)) {
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struct kvm_async_pf *work =
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list_first_entry(&vcpu->async_pf.queue,
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typeof(*work), queue);
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list_del(&work->queue);
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/*
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* We know it's present in vcpu->async_pf.done, do
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* nothing here.
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*/
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if (!work->vcpu)
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continue;
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spin_unlock(&vcpu->async_pf.lock);
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#ifdef CONFIG_KVM_ASYNC_PF_SYNC
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flush_work(&work->work);
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#else
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if (cancel_work_sync(&work->work)) {
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mmput(work->mm);
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kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */
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kmem_cache_free(async_pf_cache, work);
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}
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#endif
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spin_lock(&vcpu->async_pf.lock);
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}
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while (!list_empty(&vcpu->async_pf.done)) {
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struct kvm_async_pf *work =
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list_first_entry(&vcpu->async_pf.done,
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typeof(*work), link);
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list_del(&work->link);
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kmem_cache_free(async_pf_cache, work);
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}
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spin_unlock(&vcpu->async_pf.lock);
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vcpu->async_pf.queued = 0;
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}
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void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
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{
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struct kvm_async_pf *work;
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while (!list_empty_careful(&vcpu->async_pf.done) &&
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kvm_arch_can_inject_async_page_present(vcpu)) {
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spin_lock(&vcpu->async_pf.lock);
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work = list_first_entry(&vcpu->async_pf.done, typeof(*work),
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link);
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list_del(&work->link);
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spin_unlock(&vcpu->async_pf.lock);
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kvm_arch_async_page_ready(vcpu, work);
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kvm_async_page_present_async(vcpu, work);
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list_del(&work->queue);
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vcpu->async_pf.queued--;
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kmem_cache_free(async_pf_cache, work);
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}
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}
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int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, unsigned long hva,
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struct kvm_arch_async_pf *arch)
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{
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struct kvm_async_pf *work;
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if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU)
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return 0;
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/* setup delayed work */
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/*
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* do alloc nowait since if we are going to sleep anyway we
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* may as well sleep faulting in page
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*/
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work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT | __GFP_NOWARN);
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if (!work)
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return 0;
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work->wakeup_all = false;
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work->vcpu = vcpu;
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work->gva = gva;
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work->addr = hva;
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work->arch = *arch;
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work->mm = current->mm;
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mmget(work->mm);
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kvm_get_kvm(work->vcpu->kvm);
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/* this can't really happen otherwise gfn_to_pfn_async
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would succeed */
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if (unlikely(kvm_is_error_hva(work->addr)))
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goto retry_sync;
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INIT_WORK(&work->work, async_pf_execute);
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if (!schedule_work(&work->work))
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goto retry_sync;
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list_add_tail(&work->queue, &vcpu->async_pf.queue);
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vcpu->async_pf.queued++;
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kvm_arch_async_page_not_present(vcpu, work);
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return 1;
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retry_sync:
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kvm_put_kvm(work->vcpu->kvm);
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mmput(work->mm);
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kmem_cache_free(async_pf_cache, work);
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return 0;
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}
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int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
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{
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struct kvm_async_pf *work;
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if (!list_empty_careful(&vcpu->async_pf.done))
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return 0;
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work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
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if (!work)
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return -ENOMEM;
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work->wakeup_all = true;
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INIT_LIST_HEAD(&work->queue); /* for list_del to work */
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spin_lock(&vcpu->async_pf.lock);
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list_add_tail(&work->link, &vcpu->async_pf.done);
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spin_unlock(&vcpu->async_pf.lock);
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vcpu->async_pf.queued++;
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return 0;
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}
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