On 26.08.25 02:55, Jason Andryuk wrote:

VIRQs come in 3 flavors, per-VPU, per-domain, and global, and the VIRQs are tracked in per-cpu virq_to_irq arrays.

Per-domain and global VIRQs must be bound on CPU 0, and bind_virq_to_irq() sets the per_cpu virq_to_irq at registration time Later, the interrupt can migrate, and info->cpu is updated. When calling __unbind_from_irq(), the per-cpu virq_to_irq is cleared for a different cpu. If bind_virq_to_irq() is called again with CPU 0, the stale irq is returned. There won't be any irq_info for the irq, so things break.

Make xen_rebind_evtchn_to_cpu() update the per_cpu virq_to_irq mappings to keep them update to date with the current cpu. This ensures the correct virq_to_irq is cleared in __unbind_from_irq().

Fixes: e46cdb66c8fc ("xen: event channels") Cc: stable@vger.kernel.org Signed-off-by: Jason Andryuk jason.andryuk@amd.com

---

V2: Different approach changing virq_to_irq

---

drivers/xen/events/events_base.c | 11 +++++++++++ 1 file changed, 11 insertions(+)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c index a85bc43f4344..4e9db7b92dde 100644 --- a/drivers/xen/events/events_base.c +++ b/drivers/xen/events/events_base.c @@ -1772,6 +1772,7 @@ static int xen_rebind_evtchn_to_cpu(struct irq_info *info, unsigned int tcpu) { struct evtchn_bind_vcpu bind_vcpu; evtchn_port_t evtchn = info ? info->evtchn : 0;

• int old_cpu = info ? info->cpu : tcpu;

I'd prefer not to initialize old_cpu just here ...

if (!VALID_EVTCHN(evtchn)) return -1;

... as here info is always valid, so you can just use "old_cpu = info->cpu;" (probably just after the hypercall).

@@ -1795,8 +1796,18 @@ static int xen_rebind_evtchn_to_cpu(struct irq_info *info, unsigned int tcpu) * it, but don't do the xenlinux-level rebind in that case. */ if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_vcpu, &bind_vcpu) >= 0)

• {

Kernel style, please.

bind_evtchn_to_cpu(info, tcpu, false);

• if (info->type == IRQT_VIRQ) {
  

• 	int virq = info->u.virq;
  

• 	int irq = per_cpu(virq_to_irq, old_cpu)[virq];
  

• 	per_cpu(virq_to_irq, old_cpu)[virq] = -1;
  

• 	per_cpu(virq_to_irq, tcpu)[virq] = irq;
  

• }
  

• }
• do_unmask(info, EVT_MASK_REASON_TEMPORARY);

return 0;

Juergen