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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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557 lines
12 KiB
C
557 lines
12 KiB
C
/*
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* KVM paravirt_ops implementation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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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
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* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* Copyright (C) 2007, Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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* Copyright IBM Corporation, 2007
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* Authors: Anthony Liguori <aliguori@us.ibm.com>
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/kvm_para.h>
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#include <linux/cpu.h>
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#include <linux/mm.h>
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#include <linux/highmem.h>
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#include <linux/hardirq.h>
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#include <linux/notifier.h>
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#include <linux/reboot.h>
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#include <linux/hash.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/kprobes.h>
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#include <asm/timer.h>
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#include <asm/cpu.h>
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#include <asm/traps.h>
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#include <asm/desc.h>
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#include <asm/tlbflush.h>
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#define MMU_QUEUE_SIZE 1024
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static int kvmapf = 1;
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static int parse_no_kvmapf(char *arg)
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{
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kvmapf = 0;
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return 0;
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}
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early_param("no-kvmapf", parse_no_kvmapf);
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struct kvm_para_state {
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u8 mmu_queue[MMU_QUEUE_SIZE];
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int mmu_queue_len;
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};
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static DEFINE_PER_CPU(struct kvm_para_state, para_state);
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static DEFINE_PER_CPU(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
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static struct kvm_para_state *kvm_para_state(void)
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{
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return &per_cpu(para_state, raw_smp_processor_id());
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}
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/*
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* No need for any "IO delay" on KVM
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*/
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static void kvm_io_delay(void)
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{
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}
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#define KVM_TASK_SLEEP_HASHBITS 8
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#define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
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struct kvm_task_sleep_node {
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struct hlist_node link;
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wait_queue_head_t wq;
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u32 token;
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int cpu;
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bool halted;
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struct mm_struct *mm;
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};
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static struct kvm_task_sleep_head {
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spinlock_t lock;
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struct hlist_head list;
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} async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
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static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
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u32 token)
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{
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struct hlist_node *p;
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hlist_for_each(p, &b->list) {
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struct kvm_task_sleep_node *n =
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hlist_entry(p, typeof(*n), link);
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if (n->token == token)
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return n;
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}
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return NULL;
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}
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void kvm_async_pf_task_wait(u32 token)
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{
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u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
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struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
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struct kvm_task_sleep_node n, *e;
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DEFINE_WAIT(wait);
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int cpu, idle;
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cpu = get_cpu();
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idle = idle_cpu(cpu);
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put_cpu();
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spin_lock(&b->lock);
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e = _find_apf_task(b, token);
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if (e) {
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/* dummy entry exist -> wake up was delivered ahead of PF */
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hlist_del(&e->link);
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kfree(e);
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spin_unlock(&b->lock);
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return;
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}
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n.token = token;
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n.cpu = smp_processor_id();
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n.mm = current->active_mm;
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n.halted = idle || preempt_count() > 1;
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atomic_inc(&n.mm->mm_count);
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init_waitqueue_head(&n.wq);
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hlist_add_head(&n.link, &b->list);
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spin_unlock(&b->lock);
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for (;;) {
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if (!n.halted)
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prepare_to_wait(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
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if (hlist_unhashed(&n.link))
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break;
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if (!n.halted) {
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local_irq_enable();
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schedule();
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local_irq_disable();
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} else {
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/*
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* We cannot reschedule. So halt.
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*/
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native_safe_halt();
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local_irq_disable();
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}
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}
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if (!n.halted)
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finish_wait(&n.wq, &wait);
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return;
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}
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EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait);
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static void apf_task_wake_one(struct kvm_task_sleep_node *n)
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{
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hlist_del_init(&n->link);
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if (!n->mm)
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return;
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mmdrop(n->mm);
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if (n->halted)
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smp_send_reschedule(n->cpu);
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else if (waitqueue_active(&n->wq))
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wake_up(&n->wq);
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}
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static void apf_task_wake_all(void)
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{
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int i;
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for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
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struct hlist_node *p, *next;
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struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
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spin_lock(&b->lock);
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hlist_for_each_safe(p, next, &b->list) {
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struct kvm_task_sleep_node *n =
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hlist_entry(p, typeof(*n), link);
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if (n->cpu == smp_processor_id())
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apf_task_wake_one(n);
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}
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spin_unlock(&b->lock);
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}
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}
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void kvm_async_pf_task_wake(u32 token)
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{
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u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
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struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
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struct kvm_task_sleep_node *n;
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if (token == ~0) {
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apf_task_wake_all();
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return;
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}
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again:
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spin_lock(&b->lock);
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n = _find_apf_task(b, token);
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if (!n) {
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/*
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* async PF was not yet handled.
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* Add dummy entry for the token.
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*/
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n = kmalloc(sizeof(*n), GFP_ATOMIC);
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if (!n) {
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/*
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* Allocation failed! Busy wait while other cpu
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* handles async PF.
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*/
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spin_unlock(&b->lock);
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cpu_relax();
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goto again;
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}
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n->token = token;
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n->cpu = smp_processor_id();
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n->mm = NULL;
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init_waitqueue_head(&n->wq);
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hlist_add_head(&n->link, &b->list);
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} else
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apf_task_wake_one(n);
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spin_unlock(&b->lock);
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return;
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}
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EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
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u32 kvm_read_and_reset_pf_reason(void)
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{
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u32 reason = 0;
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if (__get_cpu_var(apf_reason).enabled) {
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reason = __get_cpu_var(apf_reason).reason;
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__get_cpu_var(apf_reason).reason = 0;
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}
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return reason;
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}
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EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason);
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dotraplinkage void __kprobes
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do_async_page_fault(struct pt_regs *regs, unsigned long error_code)
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{
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switch (kvm_read_and_reset_pf_reason()) {
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default:
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do_page_fault(regs, error_code);
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break;
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case KVM_PV_REASON_PAGE_NOT_PRESENT:
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/* page is swapped out by the host. */
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kvm_async_pf_task_wait((u32)read_cr2());
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break;
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case KVM_PV_REASON_PAGE_READY:
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kvm_async_pf_task_wake((u32)read_cr2());
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break;
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}
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}
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static void kvm_mmu_op(void *buffer, unsigned len)
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{
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int r;
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unsigned long a1, a2;
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do {
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a1 = __pa(buffer);
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a2 = 0; /* on i386 __pa() always returns <4G */
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r = kvm_hypercall3(KVM_HC_MMU_OP, len, a1, a2);
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buffer += r;
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len -= r;
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} while (len);
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}
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static void mmu_queue_flush(struct kvm_para_state *state)
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{
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if (state->mmu_queue_len) {
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kvm_mmu_op(state->mmu_queue, state->mmu_queue_len);
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state->mmu_queue_len = 0;
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}
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}
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static void kvm_deferred_mmu_op(void *buffer, int len)
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{
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struct kvm_para_state *state = kvm_para_state();
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if (paravirt_get_lazy_mode() != PARAVIRT_LAZY_MMU) {
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kvm_mmu_op(buffer, len);
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return;
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}
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if (state->mmu_queue_len + len > sizeof state->mmu_queue)
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mmu_queue_flush(state);
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memcpy(state->mmu_queue + state->mmu_queue_len, buffer, len);
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state->mmu_queue_len += len;
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}
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static void kvm_mmu_write(void *dest, u64 val)
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{
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__u64 pte_phys;
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struct kvm_mmu_op_write_pte wpte;
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#ifdef CONFIG_HIGHPTE
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struct page *page;
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unsigned long dst = (unsigned long) dest;
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page = kmap_atomic_to_page(dest);
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pte_phys = page_to_pfn(page);
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pte_phys <<= PAGE_SHIFT;
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pte_phys += (dst & ~(PAGE_MASK));
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#else
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pte_phys = (unsigned long)__pa(dest);
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#endif
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wpte.header.op = KVM_MMU_OP_WRITE_PTE;
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wpte.pte_val = val;
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wpte.pte_phys = pte_phys;
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kvm_deferred_mmu_op(&wpte, sizeof wpte);
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}
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/*
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* We only need to hook operations that are MMU writes. We hook these so that
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* we can use lazy MMU mode to batch these operations. We could probably
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* improve the performance of the host code if we used some of the information
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* here to simplify processing of batched writes.
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*/
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static void kvm_set_pte(pte_t *ptep, pte_t pte)
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{
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kvm_mmu_write(ptep, pte_val(pte));
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}
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static void kvm_set_pte_at(struct mm_struct *mm, unsigned long addr,
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pte_t *ptep, pte_t pte)
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{
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kvm_mmu_write(ptep, pte_val(pte));
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}
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static void kvm_set_pmd(pmd_t *pmdp, pmd_t pmd)
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{
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kvm_mmu_write(pmdp, pmd_val(pmd));
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}
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#if PAGETABLE_LEVELS >= 3
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#ifdef CONFIG_X86_PAE
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static void kvm_set_pte_atomic(pte_t *ptep, pte_t pte)
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{
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kvm_mmu_write(ptep, pte_val(pte));
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}
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static void kvm_pte_clear(struct mm_struct *mm,
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unsigned long addr, pte_t *ptep)
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{
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kvm_mmu_write(ptep, 0);
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}
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static void kvm_pmd_clear(pmd_t *pmdp)
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{
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kvm_mmu_write(pmdp, 0);
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}
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#endif
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static void kvm_set_pud(pud_t *pudp, pud_t pud)
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{
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kvm_mmu_write(pudp, pud_val(pud));
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}
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#if PAGETABLE_LEVELS == 4
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static void kvm_set_pgd(pgd_t *pgdp, pgd_t pgd)
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{
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kvm_mmu_write(pgdp, pgd_val(pgd));
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}
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#endif
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#endif /* PAGETABLE_LEVELS >= 3 */
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static void kvm_flush_tlb(void)
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{
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struct kvm_mmu_op_flush_tlb ftlb = {
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.header.op = KVM_MMU_OP_FLUSH_TLB,
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};
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kvm_deferred_mmu_op(&ftlb, sizeof ftlb);
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}
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static void kvm_release_pt(unsigned long pfn)
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{
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struct kvm_mmu_op_release_pt rpt = {
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.header.op = KVM_MMU_OP_RELEASE_PT,
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.pt_phys = (u64)pfn << PAGE_SHIFT,
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};
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kvm_mmu_op(&rpt, sizeof rpt);
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}
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static void kvm_enter_lazy_mmu(void)
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{
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paravirt_enter_lazy_mmu();
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}
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static void kvm_leave_lazy_mmu(void)
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{
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struct kvm_para_state *state = kvm_para_state();
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mmu_queue_flush(state);
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paravirt_leave_lazy_mmu();
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}
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static void __init paravirt_ops_setup(void)
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{
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pv_info.name = "KVM";
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pv_info.paravirt_enabled = 1;
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if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
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pv_cpu_ops.io_delay = kvm_io_delay;
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if (kvm_para_has_feature(KVM_FEATURE_MMU_OP)) {
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pv_mmu_ops.set_pte = kvm_set_pte;
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pv_mmu_ops.set_pte_at = kvm_set_pte_at;
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pv_mmu_ops.set_pmd = kvm_set_pmd;
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#if PAGETABLE_LEVELS >= 3
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#ifdef CONFIG_X86_PAE
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pv_mmu_ops.set_pte_atomic = kvm_set_pte_atomic;
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pv_mmu_ops.pte_clear = kvm_pte_clear;
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pv_mmu_ops.pmd_clear = kvm_pmd_clear;
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#endif
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pv_mmu_ops.set_pud = kvm_set_pud;
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#if PAGETABLE_LEVELS == 4
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pv_mmu_ops.set_pgd = kvm_set_pgd;
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#endif
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#endif
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pv_mmu_ops.flush_tlb_user = kvm_flush_tlb;
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pv_mmu_ops.release_pte = kvm_release_pt;
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pv_mmu_ops.release_pmd = kvm_release_pt;
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pv_mmu_ops.release_pud = kvm_release_pt;
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pv_mmu_ops.lazy_mode.enter = kvm_enter_lazy_mmu;
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pv_mmu_ops.lazy_mode.leave = kvm_leave_lazy_mmu;
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}
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#ifdef CONFIG_X86_IO_APIC
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no_timer_check = 1;
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#endif
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}
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void __cpuinit kvm_guest_cpu_init(void)
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{
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if (!kvm_para_available())
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return;
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if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) {
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u64 pa = __pa(&__get_cpu_var(apf_reason));
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#ifdef CONFIG_PREEMPT
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pa |= KVM_ASYNC_PF_SEND_ALWAYS;
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#endif
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wrmsrl(MSR_KVM_ASYNC_PF_EN, pa | KVM_ASYNC_PF_ENABLED);
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__get_cpu_var(apf_reason).enabled = 1;
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printk(KERN_INFO"KVM setup async PF for cpu %d\n",
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smp_processor_id());
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}
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}
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static void kvm_pv_disable_apf(void *unused)
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{
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if (!__get_cpu_var(apf_reason).enabled)
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return;
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wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
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__get_cpu_var(apf_reason).enabled = 0;
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printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
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smp_processor_id());
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}
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static int kvm_pv_reboot_notify(struct notifier_block *nb,
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unsigned long code, void *unused)
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{
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if (code == SYS_RESTART)
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on_each_cpu(kvm_pv_disable_apf, NULL, 1);
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return NOTIFY_DONE;
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}
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static struct notifier_block kvm_pv_reboot_nb = {
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.notifier_call = kvm_pv_reboot_notify,
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};
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#ifdef CONFIG_SMP
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static void __init kvm_smp_prepare_boot_cpu(void)
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{
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#ifdef CONFIG_KVM_CLOCK
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WARN_ON(kvm_register_clock("primary cpu clock"));
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#endif
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kvm_guest_cpu_init();
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native_smp_prepare_boot_cpu();
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}
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static void kvm_guest_cpu_online(void *dummy)
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{
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kvm_guest_cpu_init();
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}
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static void kvm_guest_cpu_offline(void *dummy)
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{
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kvm_pv_disable_apf(NULL);
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apf_task_wake_all();
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}
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static int __cpuinit kvm_cpu_notify(struct notifier_block *self,
|
|
unsigned long action, void *hcpu)
|
|
{
|
|
int cpu = (unsigned long)hcpu;
|
|
switch (action) {
|
|
case CPU_ONLINE:
|
|
case CPU_DOWN_FAILED:
|
|
case CPU_ONLINE_FROZEN:
|
|
smp_call_function_single(cpu, kvm_guest_cpu_online, NULL, 0);
|
|
break;
|
|
case CPU_DOWN_PREPARE:
|
|
case CPU_DOWN_PREPARE_FROZEN:
|
|
smp_call_function_single(cpu, kvm_guest_cpu_offline, NULL, 1);
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
static struct notifier_block __cpuinitdata kvm_cpu_notifier = {
|
|
.notifier_call = kvm_cpu_notify,
|
|
};
|
|
#endif
|
|
|
|
static void __init kvm_apf_trap_init(void)
|
|
{
|
|
set_intr_gate(14, &async_page_fault);
|
|
}
|
|
|
|
void __init kvm_guest_init(void)
|
|
{
|
|
int i;
|
|
|
|
if (!kvm_para_available())
|
|
return;
|
|
|
|
paravirt_ops_setup();
|
|
register_reboot_notifier(&kvm_pv_reboot_nb);
|
|
for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
|
|
spin_lock_init(&async_pf_sleepers[i].lock);
|
|
if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
|
|
x86_init.irqs.trap_init = kvm_apf_trap_init;
|
|
|
|
#ifdef CONFIG_SMP
|
|
smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
|
|
register_cpu_notifier(&kvm_cpu_notifier);
|
|
#else
|
|
kvm_guest_cpu_init();
|
|
#endif
|
|
}
|