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, 1 insertions, 5 deletions

diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index fadf4408a820..15a83b93566d 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -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.