[PATCH 4/9] xen: Add support to check if IRQ line is shared with other domains.

[Konrad Rzeszutek Wilk]

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 IRQ line.

[v2: Deal with v2.6.37-rc1 rebase fallout]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 drivers/xen/events.c |   13 +++++++++++++
 include/xen/events.h |    3 +++
 2 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 96c93e7..690dfad 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -1398,6 +1398,19 @@ 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_ignore_irq(int irq)
+{
+	struct irq_info *info = info_for_irq(irq);
+	struct physdev_irq_status_query irq_status = { .irq =
+							info->u.pirq.gsi };
+
+	if (HYPERVISOR_physdev_op(PHYSDEVOP_irq_status_query, &irq_status))
+		return 0;
+	return !(irq_status.flags & XENIRQSTAT_shared);
+}
+EXPORT_SYMBOL_GPL(xen_ignore_irq);
+
 void xen_irq_resume(void)
 {
 	unsigned int cpu, irq, evtchn;
diff --git a/include/xen/events.h b/include/xen/events.h
index 646dd17..553c664 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -89,4 +89,7 @@ int xen_vector_from_irq(unsigned pirq);
 /* Return gsi allocated to pirq */
 int xen_gsi_from_irq(unsigned pirq);
 
+/* Determine whether to ignore this IRQ if passed to a guest. */
+int xen_ignore_irq(int irq);
+
 #endif	/* _XEN_EVENTS_H */
-- 
1.7.1

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