[PATCH 2/3] xen/pv-on-hvm kexec: rebind virqs to existing eventchannel ports

Olaf Hering
2011-08-04T16:22:07Z

[-- Attachment #1: xen.kexec.find_virq.patch --]
[-- Type: text/plain, Size: 2109 bytes --]

During a kexec boot some virqs such as timer and debugirq were already
registered by the old kernel. The hypervisor will return -EEXISTS from
the new EVTCHNOP_bind_virq request and the BUG in bind_virq_to_irq()
triggers. Catch the -EEXISTS error and loop through all possible ports to find
what port belongs to the virq/cpu combo.

Signed-off-by: Olaf Hering <olaf@aepfle.de>

---
drivers/xen/events.c | 40 +++++++++++++++++++++++++++++++++++-----
1 file changed, 35 insertions(+), 5 deletions(-)

Index: linux-3.0/drivers/xen/events.c
===================================================================
--- linux-3.0.orig/drivers/xen/events.c
+++ linux-3.0/drivers/xen/events.c
@@ -877,11 +877,35 @@ static int bind_interdomain_evtchn_to_ir
return err ? : bind_evtchn_to_irq(bind_interdomain.local_port);
}

+/* BITS_PER_LONG is used in Xen */
+#define MAX_EVTCHNS (64 * 64)
+
+static int find_virq(unsigned int virq, unsigned int cpu)
+{
+ struct evtchn_status status;
+ int port, rc = -ENOENT;
+
+ memset(&status, 0, sizeof(status));
+ for (port = 0; port <= MAX_EVTCHNS; port++) {
+ status.dom = DOMID_SELF;
+ status.port = port;
+ rc = HYPERVISOR_event_channel_op(EVTCHNOP_status, &status);
+ if (rc < 0)
+ continue;
+ if (status.status != EVTCHNSTAT_virq)
+ continue;
+ if (status.u.virq == virq && status.vcpu == cpu) {
+ rc = port;
+ break;
+ }
+ }
+ return rc;
+}

int bind_virq_to_irq(unsigned int virq, unsigned int cpu)
{
struct evtchn_bind_virq bind_virq;
- int evtchn, irq;
+ int evtchn, irq, ret;

spin_lock(&irq_mapping_update_lock);

@@ -897,10 +921,16 @@ int bind_virq_to_irq(unsigned int virq,

bind_virq.virq = virq;
bind_virq.vcpu = cpu;
- if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
- &bind_virq) != 0)
- BUG();
- evtchn = bind_virq.port;
+ ret = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
+ &bind_virq);
+ if (ret == 0)
+ evtchn = bind_virq.port;
+ else {
+ if (ret == -EEXIST)
+ ret = find_virq(virq, cpu);
+ BUG_ON(ret < 0);
+ evtchn = ret;
+ }

xen_irq_info_virq_init(cpu, irq, evtchn, virq);