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xen/events: Return -EEXIST for bound VIRQs 

Change find_virq() to return -EEXIST when a VIRQ is bound to a
different CPU than the one passed in.  With that, remove the BUG_ON()
from bind_virq_to_irq() to propogate the error upwards.

Some VIRQs are per-cpu, but others are per-domain or global.  Those must
be bound to CPU0 and can then migrate elsewhere.  The lookup for
per-domain and global will probably fail when migrated off CPU 0,
especially when the current CPU is tracked.  This now returns -EEXIST
instead of BUG_ON().

A second call to bind a per-domain or global VIRQ is not expected, but
make it non-fatal to avoid trying to look up the irq, since we don't
know which per_cpu(virq_to_irq) it will be in.

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: <20250828003604.8949-3-jason.andryuk@amd.com>
pull/1354/merge
Jason Andryuk 2025-08-27 20:36:02 -04:00 committed by Juergen Gross
parent 08df2d7dd4
commit 07ce121d93
1 changed files with 14 additions and 5 deletions
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19
drivers/xen/events/events_base.c
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@ -1314,10 +1314,12 @@ int bind_interdomain_evtchn_to_irq_lateeoi(struct xenbus_device *dev,
}
EXPORT_SYMBOL_GPL(bind_interdomain_evtchn_to_irq_lateeoi);
static int find_virq(unsigned int virq, unsigned int cpu, evtchn_port_t *evtchn)
static int find_virq(unsigned int virq, unsigned int cpu, evtchn_port_t *evtchn,
bool percpu)
{
struct evtchn_status status;
evtchn_port_t port;
bool exists = false;
memset(&status, 0, sizeof(status));
for (port = 0; port < xen_evtchn_max_channels(); port++) {
@ -1330,12 +1332,16 @@ static int find_virq(unsigned int virq, unsigned int cpu, evtchn_port_t *evtchn)
continue;
if (status.status != EVTCHNSTAT_virq)
continue;
if (status.u.virq == virq && status.vcpu == xen_vcpu_nr(cpu)) {
if (status.u.virq != virq)
continue;
if (status.vcpu == xen_vcpu_nr(cpu)) {
*evtchn = port;
return 0;
} else if (!percpu) {
exists = true;
}
}
return -ENOENT;
return exists ? -EEXIST : -ENOENT;
}
/**
@ -1382,8 +1388,11 @@ int bind_virq_to_irq(unsigned int virq, unsigned int cpu, bool percpu)
evtchn = bind_virq.port;
else {
if (ret == -EEXIST)
ret = find_virq(virq, cpu, &evtchn);
BUG_ON(ret < 0);
ret = find_virq(virq, cpu, &evtchn, percpu);
if (ret) {
__unbind_from_irq(info, info->irq);
goto out;
}
}
ret = xen_irq_info_virq_setup(info, cpu, evtchn, virq);