// SPDX-License-Identifier: GPL-2.0-or-later
/*
* KVM paravirt_ops implementation
*
* Copyright (C) 2007, Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
* Copyright IBM Corporation, 2007
* Authors: Anthony Liguori <aliguori@us.ibm.com>
*/
#define pr_fmt(fmt) "kvm-guest: " fmt
#include <linux/context_tracking.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/kvm_para.h>
#include <linux/cpu.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/hardirq.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/hash.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/kprobes.h>
#include <linux/nmi.h>
#include <linux/swait.h>
#include <asm/timer.h>
#include <asm/cpu.h>
#include <asm/traps.h>
#include <asm/desc.h>
#include <asm/tlbflush.h>
#include <asm/apic.h>
#include <asm/apicdef.h>
#include <asm/hypervisor.h>
#include <asm/tlb.h>
#include <asm/cpuidle_haltpoll.h>
DEFINE_STATIC_KEY_FALSE(kvm_async_pf_enabled);
static int kvmapf = 1;
static int __init parse_no_kvmapf(char *arg)
{
kvmapf = 0;
return 0;
}
early_param("no-kvmapf", parse_no_kvmapf);
static int steal_acc = 1;
static int __init parse_no_stealacc(char *arg)
{
steal_acc = 0;
return 0;
}
early_param("no-steal-acc", parse_no_stealacc);
static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64) __visible;
static int has_steal_clock = 0;
/*
* No need for any "IO delay" on KVM
*/
static void kvm_io_delay(void)
{
}
#define KVM_TASK_SLEEP_HASHBITS 8
#define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
struct kvm_task_sleep_node {
struct hlist_node link;
struct swait_queue_head wq;
u32 token;
int cpu;
};
static struct kvm_task_sleep_head {
raw_spinlock_t lock;
struct hlist_head list;
} async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
u32 token)
{
struct hlist_node *p;
hlist_for_each(p, &b->list) {
struct kvm_task_sleep_node *n =
hlist_entry(p, typeof(*n), link);
if (n->token == token)
return n;
}
return NULL;
}
static bool kvm_async_pf_queue_task(u32 token, struct kvm_task_sleep_node *n)
{
u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
struct kvm_task_sleep_node *e;
raw_spin_lock(&b->lock);
e = _find_apf_task(b, token);
if (e) {
/* dummy entry exist -> wake up was delivered ahead of PF */
hlist_del(&e->link);
raw_spin_unlock(&b->lock);
kfree(e);
return false;
}
n->token = token;
n->cpu = smp_processor_id();
init_swait_queue_head(&n->wq);
hlist_add_head(&n->link, &b->list);
raw_spin_unlock(&b->lock);
return true;
}
/*
* kvm_async_pf_task_wait_schedule - Wait for pagefault to be handled
* @token: Token to identify the sleep node entry
*
* Invoked from the async pagefault handling code or from the VM exit page
* fault handler. In both cases RCU is watching.
*/
void kvm_async_pf_task_wait_schedule(u32 token)
{
struct kvm_task_sleep_node n;
DECLARE_SWAITQUEUE(wait);
lockdep_assert_irqs_disabled();
if (!kvm_async_pf_queue_task(token, &n))
return;
for (;;) {
prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
if (hlist_unhashed(&n.link))
break;
local_irq_enable();
schedule();
local_irq_disable();
}
finish_swait(&n.wq, &wait);
}
EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait_schedule);
static void apf_task_wake_one(struct kvm_task_sleep_node *n)
{
hlist_del_init(&n->link);
if (swq_has_sleeper(&n->wq))
swake_up_one(&n->wq);
}
static void apf_task_wake_all(void)
{
int i;
for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
struct kvm_task_sleep_node *n;
struct hlist_node *p, *next;
raw_spin_lock(&b->lock);
hlist_for_each_safe(p, next, &b->list) {
n = hlist_entry(p, typeof(*n), link);
if (n->cpu == smp_processor_id())
apf_task_wake_one(n);
}
raw_spin_unlock(&b->lock);
}
}
void kvm_async_pf_task_wake(u32 tok