KVM: Drop kvm->irq_lock lock from irq injection path
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>
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index bb4ebd8..30f70fd 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -61,10 +61,8 @@
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);
}
/*
diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index fadf440..15a83b9 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -82,8 +82,6 @@
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 @@
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 @@
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.
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 6eca153..c12c95b1 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -137,7 +137,6 @@
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 @@
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)