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KVM: Drop kvm->irq_lock lock from irq injection path

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The only thing it protects now is interrupt injection into lapic and
this can work lockless. Even now with kvm->irq_lock in place access
to lapic is not entirely serialized since vcpu access doesn't take
kvm->irq_lock.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Gleb Natapov 2009-08-24 11:54:26 +03:00 committed by Avi Kivity
parent eba0226bdf
commit 680b3648ba
7 changed files with 1 additions and 17 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
arch/ia64/kvm/kvm-ia64.c
View file

@ -982,10 +982,8 @@ long kvm_arch_vm_ioctl(struct file *filp,
goto out;
if (irqchip_in_kernel(kvm)) {
__s32 status;
mutex_lock(&kvm->irq_lock);
status = kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID,
irq_event.irq, irq_event.level);
mutex_unlock(&kvm->irq_lock);
if (ioctl == KVM_IRQ_LINE_STATUS) {
irq_event.status = status;
if (copy_to_user(argp, &irq_event,

2
arch/x86/kvm/i8254.c
View file

@ -688,10 +688,8 @@ static void __inject_pit_timer_intr(struct kvm *kvm)
struct kvm_vcpu *vcpu;
int i;
mutex_lock(&kvm->irq_lock);
kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 1);
kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 0);
mutex_unlock(&kvm->irq_lock);
/*
* Provides NMI watchdog support via Virtual Wire mode.

2
arch/x86/kvm/lapic.c
View file

@ -501,9 +501,7 @@ static void apic_send_ipi(struct kvm_lapic *apic)
irq.trig_mode, irq.level, irq.dest_mode, irq.delivery_mode,
irq.vector);
mutex_lock(&apic->vcpu->kvm->irq_lock);
kvm_irq_delivery_to_apic(apic->vcpu->kvm, apic, &irq);
mutex_unlock(&apic->vcpu->kvm->irq_lock);
}
static u32 apic_get_tmcct(struct kvm_lapic *apic)

2
arch/x86/kvm/x86.c
View file

@ -2286,10 +2286,8 @@ long kvm_arch_vm_ioctl(struct file *filp,
goto out;
if (irqchip_in_kernel(kvm)) {
__s32 status;
mutex_lock(&kvm->irq_lock);
status = kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID,
irq_event.irq, irq_event.level);
mutex_unlock(&kvm->irq_lock);
if (ioctl == KVM_IRQ_LINE_STATUS) {
irq_event.status = status;
if (copy_to_user(argp, &irq_event,

2
virt/kvm/eventfd.c
View file

@ -61,10 +61,8 @@ irqfd_inject(struct work_struct *work)
struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
struct kvm *kvm = irqfd->kvm;
mutex_lock(&kvm->irq_lock);
kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1);
kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0);
mutex_unlock(&kvm->irq_lock);
}
/*

6
virt/kvm/irq_comm.c
View file

@ -82,8 +82,6 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
int i, r = -1;
struct kvm_vcpu *vcpu, *lowest = NULL;
WARN_ON(!mutex_is_locked(&kvm->irq_lock));
if (irq->dest_mode == 0 && irq->dest_id == 0xff &&
kvm_is_dm_lowest_prio(irq))
printk(KERN_INFO "kvm: apic: phys broadcast and lowest prio\n");
@ -138,7 +136,7 @@ static int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
return kvm_irq_delivery_to_apic(kvm, NULL, &irq);
}
/* This should be called with the kvm->irq_lock mutex held
/*
* Return value:
* < 0 Interrupt was ignored (masked or not delivered for other reasons)
* = 0 Interrupt was coalesced (previous irq is still pending)
@ -153,8 +151,6 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level)
trace_kvm_set_irq(irq, level, irq_source_id);
WARN_ON(!mutex_is_locked(&kvm->irq_lock));
/* 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.

2
virt/kvm/kvm_main.c
View file

@ -137,7 +137,6 @@ static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work)
interrupt_work);
kvm = assigned_dev->kvm;
mutex_lock(&kvm->irq_lock);
spin_lock_irq(&assigned_dev->assigned_dev_lock);
if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_HOST_MSIX) {
struct kvm_guest_msix_entry *guest_entries =
@ -156,7 +155,6 @@ static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work)
assigned_dev->guest_irq, 1);
spin_unlock_irq(&assigned_dev->assigned_dev_lock);
mutex_unlock(&assigned_dev->kvm->irq_lock);
}
static irqreturn_t kvm_assigned_dev_intr(int irq, void *dev_id)