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>

1 files changed, 0 insertions, 2 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 6eca153e1a02..c12c95b1b641 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -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)