linux/arch/x86/kvm/irq.c
Marcelo Tosatti 3cf57fed21 KVM: PIT: fix injection logic and count
The PIT injection logic is problematic under the following cases:

1) If there is a higher priority vector to be delivered by the time
kvm_pit_timer_intr_post is invoked ps->inject_pending won't be set.
This opens the possibility for missing many PIT event injections (say if
guest executes hlt at this point).

2) ps->inject_pending is racy with more than two vcpus. Since there's no locking
around read/dec of pt->pending, two vcpu's can inject two interrupts for a single
pt->pending count.

Fix 1 by using an irq ack notifier: only reinject when the previous irq
has been acked. Fix 2 with appropriate locking around manipulation of
pending count and irq_ack by the injection / ack paths.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-10-15 10:15:17 +02:00

135 lines
3.3 KiB
C

/*
* irq.c: API for in kernel interrupt controller
* Copyright (c) 2007, Intel Corporation.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 59 Temple
* Place - Suite 330, Boston, MA 02111-1307 USA.
* Authors:
* Yaozu (Eddie) Dong <Eddie.dong@intel.com>
*
*/
#include <linux/module.h>
#include <linux/kvm_host.h>
#include "irq.h"
#include "i8254.h"
/*
* check if there are pending timer events
* to be processed.
*/
int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
{
int ret;
ret = pit_has_pending_timer(vcpu);
ret |= apic_has_pending_timer(vcpu);
return ret;
}
EXPORT_SYMBOL(kvm_cpu_has_pending_timer);
/*
* check if there is pending interrupt without
* intack.
*/
int kvm_cpu_has_interrupt(struct kvm_vcpu *v)
{
struct kvm_pic *s;
if (kvm_apic_has_interrupt(v) == -1) { /* LAPIC */
if (kvm_apic_accept_pic_intr(v)) {
s = pic_irqchip(v->kvm); /* PIC */
return s->output;
} else
return 0;
}
return 1;
}
EXPORT_SYMBOL_GPL(kvm_cpu_has_interrupt);
/*
* Read pending interrupt vector and intack.
*/
int kvm_cpu_get_interrupt(struct kvm_vcpu *v)
{
struct kvm_pic *s;
int vector;
vector = kvm_get_apic_interrupt(v); /* APIC */
if (vector == -1) {
if (kvm_apic_accept_pic_intr(v)) {
s = pic_irqchip(v->kvm);
s->output = 0; /* PIC */
vector = kvm_pic_read_irq(v->kvm);
}
}
return vector;
}
EXPORT_SYMBOL_GPL(kvm_cpu_get_interrupt);
void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu)
{
kvm_inject_apic_timer_irqs(vcpu);
kvm_inject_pit_timer_irqs(vcpu);
/* TODO: PIT, RTC etc. */
}
EXPORT_SYMBOL_GPL(kvm_inject_pending_timer_irqs);
void kvm_timer_intr_post(struct kvm_vcpu *vcpu, int vec)
{
kvm_apic_timer_intr_post(vcpu, vec);
/* TODO: PIT, RTC etc. */
}
EXPORT_SYMBOL_GPL(kvm_timer_intr_post);
void __kvm_migrate_timers(struct kvm_vcpu *vcpu)
{
__kvm_migrate_apic_timer(vcpu);
__kvm_migrate_pit_timer(vcpu);
}
/* This should be called with the kvm->lock mutex held */
void kvm_set_irq(struct kvm *kvm, int irq, int level)
{
/* Not possible to detect if the guest uses the PIC or the
* IOAPIC. So set the bit in both. The guest will ignore
* writes to the unused one.
*/
kvm_ioapic_set_irq(kvm->arch.vioapic, irq, level);
kvm_pic_set_irq(pic_irqchip(kvm), irq, level);
}
void kvm_notify_acked_irq(struct kvm *kvm, unsigned gsi)
{
struct kvm_irq_ack_notifier *kian;
struct hlist_node *n;
hlist_for_each_entry(kian, n, &kvm->arch.irq_ack_notifier_list, link)
if (kian->gsi == gsi)
kian->irq_acked(kian);
}
void kvm_register_irq_ack_notifier(struct kvm *kvm,
struct kvm_irq_ack_notifier *kian)
{
hlist_add_head(&kian->link, &kvm->arch.irq_ack_notifier_list);
}
void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
struct kvm_irq_ack_notifier *kian)
{
hlist_del(&kian->link);
}