[PATCH v6 2/6] vfio: Introduce vGPU display irq type

[Tina Zhang <tina.zhang@intel.com>]

Introduce vGPU specific irq type VFIO_IRQ_TYPE_GFX, and
VFIO_IRQ_SUBTYPE_GFX_DISPLAY_IRQ as the subtype for vGPU display.

Introduce vfio_irq_info_cap_display_plane_events capability to notify
user space with the vGPU's plane update events

v3:
- Add more description to VFIO_IRQ_SUBTYPE_GFX_DISPLAY_IRQ and
  VFIO_IRQ_INFO_CAP_DISPLAY. (Alex & Gerd)

v2:
- Add VFIO_IRQ_SUBTYPE_GFX_DISPLAY_IRQ description. (Alex & Kechen)
- Introduce vfio_irq_info_cap_display_plane_events. (Gerd & Alex)

Signed-off-by: Tina Zhang <tina.zhang@intel.com>
---
 include/uapi/linux/vfio.h | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index aa6850f1daef..2946a028b0c3 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -476,6 +476,44 @@ struct vfio_irq_info_cap_type {
 	__u32 subtype;  /* type specific */
 };
 
+/* vGPU IRQ TYPE */
+#define VFIO_IRQ_TYPE_GFX			(1)
+
+/* sub-types for VFIO_IRQ_TYPE_GFX */
+/*
+ * vGPU device display refresh interrupt request. This irq asking for
+ * a user space display refresh, covers all display updates events,
+ * i.e. user space can stop the display update timer and fully depend
+ * on getting the notification if an update is needed.
+ */
+#define VFIO_IRQ_SUBTYPE_GFX_DISPLAY_IRQ	(1)
+
+/*
+ * Display capability of reporting display refresh interrupt events.
+ * This gives user space the capability to identify different display
+ * updates events of the display refresh interrupt request.
+ *
+ * When notified by VFIO_IRQ_SUBTYPE_GFX_DISPLAY_IRQ, user space can
+ * use the eventfd counter value to identify which plane has been
+ * updated.
+ *
+ * Note that there might be some cases like counter_value >
+ * (cur_event_val + pri_event_val), if notifications haven't been
+ * handled on time in user mode. These cases can be handled as all
+ * plane updated case or signle plane updated case depending on the
+ * value.
+ *
+ * cur_event_val: eventfd counter value for cursor plane change event.
+ * pri_event_val: eventfd counter value for primary plane change event.
+ */
+#define VFIO_IRQ_INFO_CAP_DISPLAY	2
+
+struct vfio_irq_info_cap_display_plane_events {
+	struct vfio_info_cap_header header;
+	__u64 cur_event_val;
+	__u64 pri_event_val;
+};
+
 /**
  * VFIO_DEVICE_SET_IRQS - _IOW(VFIO_TYPE, VFIO_BASE + 10, struct vfio_irq_set)
  *
-- 
2.17.1