Commit 3fcc8e14 authored Aug 27, 2025 by Jason Andryuk Committed by Juergen Gross Sep 09, 2025

xen/events: Update virq_to_irq on migration



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: e46cdb66 ("xen: event channels")
Cc: stable@vger.kernel.org
Signed-off-by: Jason Andryuk <jason.andryuk@amd.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Message-ID: <20250828003604.8949-4-jason.andryuk@amd.com>

parent 07ce121d

drivers/xen/events/events_base.c

+12 −1

Original line number	Diff line number	Diff line
		@@ -1797,9 +1797,20 @@ static int xen_rebind_evtchn_to_cpu(struct irq_info *info, unsigned int tcpu)
		* virq or IPI channel, which don't actually need to be rebound. Ignore
		* it, but don't do the xenlinux-level rebind in that case.
		*/
		if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_vcpu, &bind_vcpu) >= 0)
		if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_vcpu, &bind_vcpu) >= 0) {
		int old_cpu = info->cpu;

		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;