662 строки
15 KiB
C
662 строки
15 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/context_tracking.h>
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#include <linux/init.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 <linux/debugfs.h>
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#include <linux/nmi.h>
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#include <linux/swait.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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#include <asm/apic.h>
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#include <asm/apicdef.h>
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#include <asm/hypervisor.h>
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#include <asm/kvm_guest.h>
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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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static int steal_acc = 1;
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static int parse_no_stealacc(char *arg)
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{
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steal_acc = 0;
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return 0;
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}
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early_param("no-steal-acc", parse_no_stealacc);
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static int kvmclock_vsyscall = 1;
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static int parse_no_kvmclock_vsyscall(char *arg)
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{
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kvmclock_vsyscall = 0;
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return 0;
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}
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early_param("no-kvmclock-vsyscall", parse_no_kvmclock_vsyscall);
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static DEFINE_PER_CPU(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
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static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64);
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static int has_steal_clock = 0;
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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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struct swait_queue_head wq;
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u32 token;
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int cpu;
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bool halted;
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};
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static struct kvm_task_sleep_head {
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raw_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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/*
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* @interrupt_kernel: Is this called from a routine which interrupts the kernel
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* (other than user space)?
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*/
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void kvm_async_pf_task_wait(u32 token, int interrupt_kernel)
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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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DECLARE_SWAITQUEUE(wait);
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rcu_irq_enter();
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raw_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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raw_spin_unlock(&b->lock);
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rcu_irq_exit();
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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.halted = is_idle_task(current) ||
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(IS_ENABLED(CONFIG_PREEMPT_COUNT)
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? preempt_count() > 1 || rcu_preempt_depth()
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: interrupt_kernel);
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init_swait_queue_head(&n.wq);
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hlist_add_head(&n.link, &b->list);
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raw_spin_unlock(&b->lock);
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for (;;) {
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if (!n.halted)
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prepare_to_swait(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
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if (hlist_unhashed(&n.link))
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break;
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rcu_irq_exit();
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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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rcu_irq_enter();
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}
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if (!n.halted)
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finish_swait(&n.wq, &wait);
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rcu_irq_exit();
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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->halted)
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smp_send_reschedule(n->cpu);
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else if (swq_has_sleeper(&n->wq))
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swake_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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raw_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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raw_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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raw_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 = kzalloc(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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raw_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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init_swait_queue_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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raw_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 (__this_cpu_read(apf_reason.enabled)) {
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reason = __this_cpu_read(apf_reason.reason);
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__this_cpu_write(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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NOKPROBE_SYMBOL(kvm_read_and_reset_pf_reason);
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dotraplinkage void
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do_async_page_fault(struct pt_regs *regs, unsigned long error_code)
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{
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enum ctx_state prev_state;
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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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prev_state = exception_enter();
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kvm_async_pf_task_wait((u32)read_cr2(), !user_mode(regs));
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exception_exit(prev_state);
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break;
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case KVM_PV_REASON_PAGE_READY:
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rcu_irq_enter();
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kvm_async_pf_task_wake((u32)read_cr2());
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rcu_irq_exit();
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break;
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}
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}
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NOKPROBE_SYMBOL(do_async_page_fault);
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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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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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#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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static void kvm_register_steal_time(void)
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{
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int cpu = smp_processor_id();
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struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
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if (!has_steal_clock)
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return;
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wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
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pr_info("kvm-stealtime: cpu %d, msr %llx\n",
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cpu, (unsigned long long) slow_virt_to_phys(st));
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}
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static DEFINE_PER_CPU(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
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static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val)
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{
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/**
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* This relies on __test_and_clear_bit to modify the memory
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* in a way that is atomic with respect to the local CPU.
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* The hypervisor only accesses this memory from the local CPU so
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* there's no need for lock or memory barriers.
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* An optimization barrier is implied in apic write.
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*/
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if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
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return;
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apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK);
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}
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static void 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 = slow_virt_to_phys(this_cpu_ptr(&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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pa |= KVM_ASYNC_PF_ENABLED;
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/* Async page fault support for L1 hypervisor is optional */
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if (wrmsr_safe(MSR_KVM_ASYNC_PF_EN,
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(pa | KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT) & 0xffffffff, pa >> 32) < 0)
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wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
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__this_cpu_write(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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if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
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unsigned long pa;
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/* Size alignment is implied but just to make it explicit. */
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BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
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__this_cpu_write(kvm_apic_eoi, 0);
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pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
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| KVM_MSR_ENABLED;
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wrmsrl(MSR_KVM_PV_EOI_EN, pa);
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}
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if (has_steal_clock)
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kvm_register_steal_time();
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}
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static void kvm_pv_disable_apf(void)
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{
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if (!__this_cpu_read(apf_reason.enabled))
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return;
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wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
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__this_cpu_write(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 void kvm_pv_guest_cpu_reboot(void *unused)
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{
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/*
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* We disable PV EOI before we load a new kernel by kexec,
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* since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory.
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* New kernel can re-enable when it boots.
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*/
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if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
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wrmsrl(MSR_KVM_PV_EOI_EN, 0);
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kvm_pv_disable_apf();
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kvm_disable_steal_time();
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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_guest_cpu_reboot, 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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static u64 kvm_steal_clock(int cpu)
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{
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u64 steal;
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struct kvm_steal_time *src;
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int version;
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src = &per_cpu(steal_time, cpu);
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do {
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version = src->version;
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virt_rmb();
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steal = src->steal;
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virt_rmb();
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} while ((version & 1) || (version != src->version));
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return steal;
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}
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void kvm_disable_steal_time(void)
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{
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if (!has_steal_clock)
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return;
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wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
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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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kvm_guest_cpu_init();
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native_smp_prepare_boot_cpu();
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kvm_spinlock_init();
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}
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static void kvm_guest_cpu_offline(void)
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{
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kvm_disable_steal_time();
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if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
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wrmsrl(MSR_KVM_PV_EOI_EN, 0);
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kvm_pv_disable_apf();
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apf_task_wake_all();
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}
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static int kvm_cpu_online(unsigned int cpu)
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{
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local_irq_disable();
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kvm_guest_cpu_init();
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local_irq_enable();
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return 0;
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}
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static int kvm_cpu_down_prepare(unsigned int cpu)
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{
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local_irq_disable();
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kvm_guest_cpu_offline();
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local_irq_enable();
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return 0;
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}
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#endif
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static void __init kvm_apf_trap_init(void)
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{
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update_intr_gate(X86_TRAP_PF, async_page_fault);
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}
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void __init kvm_guest_init(void)
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{
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int i;
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if (!kvm_para_available())
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return;
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paravirt_ops_setup();
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register_reboot_notifier(&kvm_pv_reboot_nb);
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for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
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raw_spin_lock_init(&async_pf_sleepers[i].lock);
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if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
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x86_init.irqs.trap_init = kvm_apf_trap_init;
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if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
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has_steal_clock = 1;
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pv_time_ops.steal_clock = kvm_steal_clock;
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}
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if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
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apic_set_eoi_write(kvm_guest_apic_eoi_write);
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if (kvmclock_vsyscall)
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kvm_setup_vsyscall_timeinfo();
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#ifdef CONFIG_SMP
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smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
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if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
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kvm_cpu_online, kvm_cpu_down_prepare) < 0)
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pr_err("kvm_guest: Failed to install cpu hotplug callbacks\n");
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#else
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kvm_guest_cpu_init();
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#endif
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/*
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* Hard lockup detection is enabled by default. Disable it, as guests
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* can get false positives too easily, for example if the host is
|
|
* overcommitted.
|
|
*/
|
|
hardlockup_detector_disable();
|
|
}
|
|
|
|
static noinline uint32_t __kvm_cpuid_base(void)
|
|
{
|
|
if (boot_cpu_data.cpuid_level < 0)
|
|
return 0; /* So we don't blow up on old processors */
|
|
|
|
if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
|
|
return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static inline uint32_t kvm_cpuid_base(void)
|
|
{
|
|
static int kvm_cpuid_base = -1;
|
|
|
|
if (kvm_cpuid_base == -1)
|
|
kvm_cpuid_base = __kvm_cpuid_base();
|
|
|
|
return kvm_cpuid_base;
|
|
}
|
|
|
|
bool kvm_para_available(void)
|
|
{
|
|
return kvm_cpuid_base() != 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_para_available);
|
|
|
|
unsigned int kvm_arch_para_features(void)
|
|
{
|
|
return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
|
|
}
|
|
|
|
static uint32_t __init kvm_detect(void)
|
|
{
|
|
return kvm_cpuid_base();
|
|
}
|
|
|
|
const struct hypervisor_x86 x86_hyper_kvm __refconst = {
|
|
.name = "KVM",
|
|
.detect = kvm_detect,
|
|
.x2apic_available = kvm_para_available,
|
|
};
|
|
EXPORT_SYMBOL_GPL(x86_hyper_kvm);
|
|
|
|
static __init int activate_jump_labels(void)
|
|
{
|
|
if (has_steal_clock) {
|
|
static_key_slow_inc(¶virt_steal_enabled);
|
|
if (steal_acc)
|
|
static_key_slow_inc(¶virt_steal_rq_enabled);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
arch_initcall(activate_jump_labels);
|
|
|
|
#ifdef CONFIG_PARAVIRT_SPINLOCKS
|
|
|
|
/* Kick a cpu by its apicid. Used to wake up a halted vcpu */
|
|
static void kvm_kick_cpu(int cpu)
|
|
{
|
|
int apicid;
|
|
unsigned long flags = 0;
|
|
|
|
apicid = per_cpu(x86_cpu_to_apicid, cpu);
|
|
kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
|
|
}
|
|
|
|
#include <asm/qspinlock.h>
|
|
|
|
static void kvm_wait(u8 *ptr, u8 val)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (in_nmi())
|
|
return;
|
|
|
|
local_irq_save(flags);
|
|
|
|
if (READ_ONCE(*ptr) != val)
|
|
goto out;
|
|
|
|
/*
|
|
* halt until it's our turn and kicked. Note that we do safe halt
|
|
* for irq enabled case to avoid hang when lock info is overwritten
|
|
* in irq spinlock slowpath and no spurious interrupt occur to save us.
|
|
*/
|
|
if (arch_irqs_disabled_flags(flags))
|
|
halt();
|
|
else
|
|
safe_halt();
|
|
|
|
out:
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
#ifdef CONFIG_X86_32
|
|
__visible bool __kvm_vcpu_is_preempted(long cpu)
|
|
{
|
|
struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
|
|
|
|
return !!src->preempted;
|
|
}
|
|
PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
|
|
|
|
#else
|
|
|
|
#include <asm/asm-offsets.h>
|
|
|
|
extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
|
|
|
|
/*
|
|
* Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
|
|
* restoring to/from the stack.
|
|
*/
|
|
asm(
|
|
".pushsection .text;"
|
|
".global __raw_callee_save___kvm_vcpu_is_preempted;"
|
|
".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"
|
|
"__raw_callee_save___kvm_vcpu_is_preempted:"
|
|
"movq __per_cpu_offset(,%rdi,8), %rax;"
|
|
"cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"
|
|
"setne %al;"
|
|
"ret;"
|
|
".popsection");
|
|
|
|
#endif
|
|
|
|
/*
|
|
* Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
|
|
*/
|
|
void __init kvm_spinlock_init(void)
|
|
{
|
|
if (!kvm_para_available())
|
|
return;
|
|
/* Does host kernel support KVM_FEATURE_PV_UNHALT? */
|
|
if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
|
|
return;
|
|
|
|
__pv_init_lock_hash();
|
|
pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
|
|
pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock);
|
|
pv_lock_ops.wait = kvm_wait;
|
|
pv_lock_ops.kick = kvm_kick_cpu;
|
|
|
|
if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
|
|
pv_lock_ops.vcpu_is_preempted =
|
|
PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
|
|
}
|
|
}
|
|
|
|
#endif /* CONFIG_PARAVIRT_SPINLOCKS */
|