[Xen-devel] [PATCH 3/5] xen/irq: Add support to check if IRQ line is shared with other domains.

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

We do this via the PHYSDEVOP_irq_status_query support hypervisor call.
We will get a positive value if another domain has binded its
PIRQ to the specified GSI (IRQ line).

[v2: Deal with v2.6.37-rc1 rebase fallout]
[v3: Deal with stable/irq.cleanup fallout]
[v4: xen_ignore_irq->xen_test_irq_shared]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 drivers/xen/events.c |   12 ++++++++++++
 include/xen/events.h |    3 +++
 2 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index ac0e228..0ac7a14 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -1508,6 +1508,18 @@ void xen_poll_irq(int irq)
        xen_poll_irq_timeout(irq, 0 /* no timeout */);
 }
 
+/* Check whether the IRQ line is shared with other guests. */
+int xen_test_irq_shared(int irq)
+{
+       struct irq_info *info = info_for_irq(irq);
+       struct physdev_irq_status_query irq_status = { .irq = info->u.pirq.pirq 
};
+
+       if (HYPERVISOR_physdev_op(PHYSDEVOP_irq_status_query, &irq_status))
+               return 0;
+       return !(irq_status.flags & XENIRQSTAT_shared);
+}
+EXPORT_SYMBOL_GPL(xen_test_irq_shared);
+
 void xen_irq_resume(void)
 {
        unsigned int cpu, evtchn;
diff --git a/include/xen/events.h b/include/xen/events.h
index 9aecc0b..932e540 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -95,4 +95,7 @@ int xen_destroy_irq(int irq);
 /* Return irq from pirq */
 int xen_irq_from_pirq(unsigned pirq);
 
+/* Determine whether to ignore this IRQ if it is passed to a guest. */
+int xen_test_irq_shared(int irq);
+
 #endif /* _XEN_EVENTS_H */
-- 
1.7.1


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