References: bnc#735806

# HG changeset patch
# User Jan Beulich <jbeulich@suse.com>
# Date 1325492779 -3600
# Node ID 3a22ed3ec534799b3cab55b0dc0a7380e701ecbe
# Parent  a7b2610b8e5c9a15b1f5de9a3eabf7f19d0b4199
x86/passthrough: don't leak guest IRQs

As unmap_domain_pirq_emuirq() fails on a never mapped pIRQ, it must not
be called for the non-emu-IRQ case (to prevent the entire unmap
operation failing).

Based on a suggestion from Stefano.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Yongjie Ren <yongjie.ren@intel.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

--- a/xen/arch/x86/physdev.c
+++ b/xen/arch/x86/physdev.c
@@ -228,7 +228,8 @@ static int physdev_unmap_pirq(struct phy
     if ( is_hvm_domain(d) )
     {
         spin_lock(&d->event_lock);
-        ret = unmap_domain_pirq_emuirq(d, unmap->pirq);
+        if ( domain_pirq_to_emuirq(d, unmap->pirq) != IRQ_UNBOUND )
+            ret = unmap_domain_pirq_emuirq(d, unmap->pirq);
         spin_unlock(&d->event_lock);
         if ( unmap->domid == DOMID_SELF || ret )
             goto free_domain;