xen/events: Add the hypervisor interface for the FIFO-based event channels
Add the hypercall sub-ops and the structures for the shared data used
in the FIFO-based event channel ABI.
The design document for this new ABI is available here:
http://xenbits.xen.org/people/dvrabel/event-channels-H.pdf
In summary, events are reported using a per-domain shared event array
of event words. Each event word has PENDING, LINKED and MASKED bits
and a LINK field for pointing to the next event in the event queue.
There are 16 event queues (with different priorities) per-VCPU.
Key advantages of this new ABI include:
- Support for over 100,000 events (2^17).
- 16 different event priorities.
- Improved fairness in event latency through the use of FIFOs.
The ABI is available in Xen 4.4 and later.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
diff --git a/include/xen/interface/event_channel.h b/include/xen/interface/event_channel.h
index f494292..7e6acef 100644
--- a/include/xen/interface/event_channel.h
+++ b/include/xen/interface/event_channel.h
@@ -190,6 +190,39 @@
};
typedef struct evtchn_reset evtchn_reset_t;
+/*
+ * EVTCHNOP_init_control: initialize the control block for the FIFO ABI.
+ */
+#define EVTCHNOP_init_control 11
+struct evtchn_init_control {
+ /* IN parameters. */
+ uint64_t control_gfn;
+ uint32_t offset;
+ uint32_t vcpu;
+ /* OUT parameters. */
+ uint8_t link_bits;
+ uint8_t _pad[7];
+};
+
+/*
+ * EVTCHNOP_expand_array: add an additional page to the event array.
+ */
+#define EVTCHNOP_expand_array 12
+struct evtchn_expand_array {
+ /* IN parameters. */
+ uint64_t array_gfn;
+};
+
+/*
+ * EVTCHNOP_set_priority: set the priority for an event channel.
+ */
+#define EVTCHNOP_set_priority 13
+struct evtchn_set_priority {
+ /* IN parameters. */
+ uint32_t port;
+ uint32_t priority;
+};
+
struct evtchn_op {
uint32_t cmd; /* EVTCHNOP_* */
union {
@@ -207,4 +240,39 @@
};
DEFINE_GUEST_HANDLE_STRUCT(evtchn_op);
+/*
+ * 2-level ABI
+ */
+
+#define EVTCHN_2L_NR_CHANNELS (sizeof(xen_ulong_t) * sizeof(xen_ulong_t) * 64)
+
+/*
+ * FIFO ABI
+ */
+
+/* Events may have priorities from 0 (highest) to 15 (lowest). */
+#define EVTCHN_FIFO_PRIORITY_MAX 0
+#define EVTCHN_FIFO_PRIORITY_DEFAULT 7
+#define EVTCHN_FIFO_PRIORITY_MIN 15
+
+#define EVTCHN_FIFO_MAX_QUEUES (EVTCHN_FIFO_PRIORITY_MIN + 1)
+
+typedef uint32_t event_word_t;
+
+#define EVTCHN_FIFO_PENDING 31
+#define EVTCHN_FIFO_MASKED 30
+#define EVTCHN_FIFO_LINKED 29
+#define EVTCHN_FIFO_BUSY 28
+
+#define EVTCHN_FIFO_LINK_BITS 17
+#define EVTCHN_FIFO_LINK_MASK ((1 << EVTCHN_FIFO_LINK_BITS) - 1)
+
+#define EVTCHN_FIFO_NR_CHANNELS (1 << EVTCHN_FIFO_LINK_BITS)
+
+struct evtchn_fifo_control_block {
+ uint32_t ready;
+ uint32_t _rsvd;
+ event_word_t head[EVTCHN_FIFO_MAX_QUEUES];
+};
+
#endif /* __XEN_PUBLIC_EVENT_CHANNEL_H__ */