KVM: Move IO APIC to its own lock

The allows removal of irq_lock from the injection path.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 16 insertions, 6 deletions

diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
index ccc941af4eaf..d057c0cbd245 100644
--- a/arch/x86/kvm/i8259.c
+++ b/arch/x86/kvm/i8259.c
@@ -38,7 +38,15 @@ static void pic_clear_isr(struct kvm_kpic_state *s, int irq)
         s->isr_ack |= (1 << irq);
         if (s != &s->pics_state->pics[0])
                 irq += 8;
+        /*
+         * We are dropping lock while calling ack notifiers since ack
+         * notifier callbacks for assigned devices call into PIC recursively.
+         * Other interrupt may be delivered to PIC while lock is dropped but
+         * it should be safe since PIC state is already updated at this stage.
+         */
+        spin_unlock(&s->pics_state->lock);
         kvm_notify_acked_irq(s->pics_state->kvm, SELECT_PIC(irq), irq);
+        spin_lock(&s->pics_state->lock);
 }
 
 void kvm_pic_clear_isr_ack(struct kvm *kvm)
@@ -176,16 +184,18 @@ int kvm_pic_set_irq(void *opaque, int irq, int level)
 static inline void pic_intack(struct kvm_kpic_state *s, int irq)
 {
         s->isr |= 1 << irq;
-        if (s->auto_eoi) {
-                if (s->rotate_on_auto_eoi)
-                        s->priority_add = (irq + 1) & 7;
-                pic_clear_isr(s, irq);
-        }
         /*
          * We don't clear a level sensitive interrupt here
          */
         if (!(s->elcr & (1 << irq)))
                 s->irr &= ~(1 << irq);
+
+        if (s->auto_eoi) {
+                if (s->rotate_on_auto_eoi)
+                        s->priority_add = (irq + 1) & 7;
+                pic_clear_isr(s, irq);
+        }
+
 }
 
 int kvm_pic_read_irq(struct kvm *kvm)
@@ -294,9 +304,9 @@ static void pic_ioport_write(void *opaque, u32 addr, u32 val)
                                 priority = get_priority(s, s->isr);
                                 if (priority != 8) {
                                         irq = (priority + s->priority_add) & 7;
-                                        pic_clear_isr(s, irq);
                                         if (cmd == 5)
                                                 s->priority_add = (irq + 1) & 7;
+                                        pic_clear_isr(s, irq);
                                         pic_update_irq(s->pics_state);
                                 }
                                 break;