KVM: ioapic: extract body of kvm_ioapic_set_irq

We will reuse it to process a nonzero IRR that is passed to KVM_SET_IRQCHIP.

Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index 25e16a6..270f7fe 100644 (file)
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -163,6 +163,55 @@ static bool rtc_irq_check_coalesced(struct kvm_ioapic *ioapic)
        return false;
 }
 
+static int ioapic_set_irq(struct kvm_ioapic *ioapic, unsigned int irq,
+               int irq_level, bool line_status)
+{
+       union kvm_ioapic_redirect_entry entry;
+       u32 mask = 1 << irq;
+       u32 old_irr;
+       int edge, ret;
+
+       entry = ioapic->redirtbl[irq];
+       edge = (entry.fields.trig_mode == IOAPIC_EDGE_TRIG);
+
+       if (!irq_level) {
+               ioapic->irr &= ~mask;
+               ret = 1;
+               goto out;
+       }
+
+       /*
+        * Return 0 for coalesced interrupts; for edge-triggered interrupts,
+        * this only happens if a previous edge has not been delivered due
+        * do masking.  For level interrupts, the remote_irr field tells
+        * us if the interrupt is waiting for an EOI.
+        *
+        * RTC is special: it is edge-triggered, but userspace likes to know
+        * if it has been already ack-ed via EOI because coalesced RTC
+        * interrupts lead to time drift in Windows guests.  So we track
+        * EOI manually for the RTC interrupt.
+        */
+       if (irq == RTC_GSI && line_status &&
+               rtc_irq_check_coalesced(ioapic)) {
+               ret = 0;
+               goto out;
+       }
+
+       old_irr = ioapic->irr;
+       ioapic->irr |= mask;
+       if ((edge && old_irr == ioapic->irr) ||
+           (!edge && entry.fields.remote_irr)) {
+               ret = 0;
+               goto out;
+       }
+
+       ret = ioapic_service(ioapic, irq, line_status);
+
+out:
+       trace_kvm_ioapic_set_irq(entry.bits, irq, ret == 0);
+       return ret;
+}
+
 static void update_handled_vectors(struct kvm_ioapic *ioapic)
 {
        DECLARE_BITMAP(handled_vectors, 256);
@@ -308,38 +357,15 @@ static int ioapic_service(struct kvm_ioapic *ioapic, int irq, bool line_status)
 int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int irq_source_id,
                       int level, bool line_status)
 {
-       u32 old_irr;
-       u32 mask = 1 << irq;
-       union kvm_ioapic_redirect_entry entry;
        int ret, irq_level;
 
        BUG_ON(irq < 0 || irq >= IOAPIC_NUM_PINS);
 
        spin_lock(&ioapic->lock);
-       old_irr = ioapic->irr;
        irq_level = __kvm_irq_line_state(&ioapic->irq_states[irq],
                                         irq_source_id, level);
-       entry = ioapic->redirtbl[irq];
-       if (!irq_level) {
-               ioapic->irr &= ~mask;
-               ret = 1;
-       } else {
-               int edge = (entry.fields.trig_mode == IOAPIC_EDGE_TRIG);
+       ret = ioapic_set_irq(ioapic, irq, irq_level, line_status);
 
-               if (irq == RTC_GSI && line_status &&
-                       rtc_irq_check_coalesced(ioapic)) {
-                       ret = 0; /* coalesced */
-                       goto out;
-               }
-               ioapic->irr |= mask;
-               if ((edge && old_irr != ioapic->irr) ||
-                   (!edge && !entry.fields.remote_irr))
-                       ret = ioapic_service(ioapic, irq, line_status);
-               else
-                       ret = 0; /* report coalesced interrupt */
-       }
-out:
-       trace_kvm_ioapic_set_irq(entry.bits, irq, ret == 0);
        spin_unlock(&ioapic->lock);
 
        return ret;