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xen: mask event channels while binding them to a vCPU

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Mask the event channel source before trying to bind it to a CPU, this
prevents stray interrupts from firing while assigning them and hitting the
KASSERT in xen_intr_handle_upcall.

Sponsored by: Citrix Systems R&D
This commit is contained in:
Roger Pau Monné 2014-12-10 11:42:02 +00:00
parent 1093cd82e0
commit 23ca39cf61
1 changed files with 12 additions and 11 deletions
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23
sys/x86/xen/xen_intr.c
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@ -851,7 +851,7 @@ xen_intr_assign_cpu(struct intsrc *base_isrc, u_int apic_id)
struct evtchn_bind_vcpu bind_vcpu; struct evtchn_bind_vcpu bind_vcpu;
struct xenisrc *isrc; struct xenisrc *isrc;
u_int to_cpu, vcpu_id; u_int to_cpu, vcpu_id;
int error; int error, masked;
#ifdef XENHVM #ifdef XENHVM
if (xen_vector_callback_enabled == 0) if (xen_vector_callback_enabled == 0)
@ -869,6 +869,11 @@ xen_intr_assign_cpu(struct intsrc *base_isrc, u_int apic_id)
return (EINVAL); return (EINVAL);
} }
/*
* Mask the event channel while binding it to prevent interrupt
* delivery with an inconsistent state in isrc->xi_cpu.
*/
masked = evtchn_test_and_set_mask(isrc->xi_port);
if ((isrc->xi_type == EVTCHN_TYPE_VIRQ) || if ((isrc->xi_type == EVTCHN_TYPE_VIRQ) ||
(isrc->xi_type == EVTCHN_TYPE_IPI)) { (isrc->xi_type == EVTCHN_TYPE_IPI)) {
/* /*
@ -879,29 +884,25 @@ xen_intr_assign_cpu(struct intsrc *base_isrc, u_int apic_id)
evtchn_cpu_mask_port(isrc->xi_cpu, isrc->xi_port); evtchn_cpu_mask_port(isrc->xi_cpu, isrc->xi_port);
isrc->xi_cpu = to_cpu; isrc->xi_cpu = to_cpu;
evtchn_cpu_unmask_port(isrc->xi_cpu, isrc->xi_port); evtchn_cpu_unmask_port(isrc->xi_cpu, isrc->xi_port);
mtx_unlock(&xen_intr_isrc_lock); goto out;
return (0);
} }
bind_vcpu.port = isrc->xi_port; bind_vcpu.port = isrc->xi_port;
bind_vcpu.vcpu = vcpu_id; bind_vcpu.vcpu = vcpu_id;
/*
* Allow interrupts to be fielded on the new VCPU before
* we ask the hypervisor to deliver them there.
*/
evtchn_cpu_unmask_port(to_cpu, isrc->xi_port);
error = HYPERVISOR_event_channel_op(EVTCHNOP_bind_vcpu, &bind_vcpu); error = HYPERVISOR_event_channel_op(EVTCHNOP_bind_vcpu, &bind_vcpu);
if (isrc->xi_cpu != to_cpu) { if (isrc->xi_cpu != to_cpu) {
if (error == 0) { if (error == 0) {
/* Commit to new binding by removing the old one. */ /* Commit to new binding by removing the old one. */
evtchn_cpu_mask_port(isrc->xi_cpu, isrc->xi_port); evtchn_cpu_mask_port(isrc->xi_cpu, isrc->xi_port);
isrc->xi_cpu = to_cpu; isrc->xi_cpu = to_cpu;
} else { evtchn_cpu_unmask_port(isrc->xi_cpu, isrc->xi_port);
/* Roll-back to previous binding. */
evtchn_cpu_mask_port(to_cpu, isrc->xi_port);
} }
} }
out:
if (masked == 0)
evtchn_unmask_port(isrc->xi_port);
mtx_unlock(&xen_intr_isrc_lock); mtx_unlock(&xen_intr_isrc_lock);
return (0); return (0);
#else #else