[Xen-changelog] [xen-4.1-testing] x86: re-inject emulated level pirqs in PV on HVM guests if still asserted

[Xen patchbot-4.1-testing <patchbot@xxxxxxx>]

# HG changeset patch
# User Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
# Date 1321623485 0
# Node ID 5a00ccfc63915650b8e1a262c2cad8e8d8670612
# Parent  e73ada19a69daf821aa7d80323f1bd76239b9bae
x86: re-inject emulated level pirqs in PV on HVM guests if still asserted

PV on HVM guests can loose level interrupts coming from emulated
devices if they have been remapped onto event channels.  The reason is
that we are missing the code to inject a pirq again in the guest when
the guest EOIs it, if it corresponds to an emulated level interrupt
and the interrupt is still asserted.

Fix this issue and also return error when the guest tries to get the
irq_status of a non-existing pirq.

Changes in this backport:
 - move the spinlock afterward to cover the new code only.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Committed-by: Keir Fraser <keir@xxxxxxx>
xen-unstable changeset:   24007:0526644ad2a6
xen-unstable date:        Thu Oct 27 16:07:18 2011 +0100
---


diff -r e73ada19a69d -r 5a00ccfc6391 xen/arch/x86/physdev.c
--- a/xen/arch/x86/physdev.c    Thu Nov 17 09:13:25 2011 +0000
+++ b/xen/arch/x86/physdev.c    Fri Nov 18 13:38:05 2011 +0000
@@ -268,6 +268,20 @@
             ret = pirq_guest_eoi(v->domain, eoi.irq);
         else
             ret = 0;
+        spin_lock(&v->domain->event_lock);
+        if ( is_hvm_domain(v->domain) &&
+                domain_pirq_to_emuirq(v->domain, eoi.irq) > 0 )
+        {
+            struct hvm_irq *hvm_irq = &v->domain->arch.hvm_domain.irq;
+            int gsi = domain_pirq_to_emuirq(v->domain, eoi.irq);
+
+            /* if this is a level irq and count > 0, send another
+             * notification */ 
+            if ( gsi >= NR_ISAIRQS /* ISA irqs are edge triggered */
+                    && hvm_irq->gsi_assert_count[gsi] )
+                send_guest_pirq(v->domain, eoi.irq);
+        }
+        spin_unlock(&v->domain->event_lock);
         break;
     }
 
@@ -323,9 +337,10 @@
             break;
         irq_status_query.flags = 0;
         if ( is_hvm_domain(v->domain) &&
-             domain_pirq_to_irq(v->domain, irq) <= 0 )
+                domain_pirq_to_irq(v->domain, irq) <= 0 &&
+                domain_pirq_to_emuirq(v->domain, irq) == IRQ_UNBOUND )
         {
-            ret = copy_to_guest(arg, &irq_status_query, 1) ? -EFAULT : 0;
+            ret = -EINVAL;
             break;
         }
 

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