[PATCH RFC 03/13] xen: mask event channels while changing affinity

[Roger Pau Monne]

Event channels should be masked while chaning affinity, or else we
might get spurious/lost interrupts.
---
 sys/x86/xen/xen_intr.c |   15 ++++++++++++---
 1 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/sys/x86/xen/xen_intr.c b/sys/x86/xen/xen_intr.c
index fd36e68..bc0781e 100644
--- a/sys/x86/xen/xen_intr.c
+++ b/sys/x86/xen/xen_intr.c
@@ -797,7 +797,7 @@ xen_intr_assign_cpu(struct intsrc *base_isrc, u_int apic_id)
 	struct evtchn_bind_vcpu bind_vcpu;
 	struct xenisrc *isrc;
 	u_int to_cpu, vcpu_id;
-	int error;
+	int error, masked;
 
 #ifdef XENHVM
 	if (xen_vector_callback_enabled == 0)
@@ -815,6 +815,12 @@ xen_intr_assign_cpu(struct intsrc *base_isrc, u_int apic_id)
 		return (EINVAL);
 	}
 
+	/*
+	 * Mask the event channel port so we don't receive spurious events
+	 * while changing affinity.
+	 */
+	masked = evtchn_test_and_set_mask(isrc->xi_port);
+
 	if ((isrc->xi_type == EVTCHN_TYPE_VIRQ) ||
 		(isrc->xi_type == EVTCHN_TYPE_IPI)) {
 		/*
@@ -825,8 +831,7 @@ xen_intr_assign_cpu(struct intsrc *base_isrc, u_int apic_id)
 		evtchn_cpu_mask_port(isrc->xi_cpu, isrc->xi_port);
 		isrc->xi_cpu = to_cpu;
 		evtchn_cpu_unmask_port(isrc->xi_cpu, isrc->xi_port);
-		mtx_unlock(&xen_intr_isrc_lock);
-		return (0);
+		goto out;
 	}
 
 	bind_vcpu.port = isrc->xi_port;
@@ -848,6 +853,10 @@ xen_intr_assign_cpu(struct intsrc *base_isrc, u_int apic_id)
 			evtchn_cpu_mask_port(to_cpu, isrc->xi_port);
 		}
 	}
+
+out:
+	if (!masked)
+		evtchn_unmask_port(isrc->xi_port);
 	mtx_unlock(&xen_intr_isrc_lock);
 	return (0);
 #else
-- 
1.7.7.5 (Apple Git-26)