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

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

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)


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