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Commit bf2bbe07 authored by David Vrabel's avatar David Vrabel Committed by Konrad Rzeszutek Wilk
Browse files

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: default avatarDavid Vrabel <david.vrabel@citrix.com>
Reviewed-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
parent 0dc0064a

drivers/xen/events/events_2l.c

+4 −4
Original line number Diff line number Diff line
@@ -38,12 +38,12 @@ 
/* Find the first set bit in a evtchn mask */

#define EVTCHN_FIRST_BIT(w) find_first_bit(BM(&(w)), BITS_PER_EVTCHN_WORD)



static DEFINE_PER_CPU(xen_ulong_t [NR_EVENT_CHANNELS/BITS_PER_EVTCHN_WORD],

static DEFINE_PER_CPU(xen_ulong_t [EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD],

		      cpu_evtchn_mask);



static unsigned evtchn_2l_max_channels(void)

{

	return NR_EVENT_CHANNELS;

	return EVTCHN_2L_NR_CHANNELS;

}



static void evtchn_2l_bind_to_cpu(struct irq_info *info, unsigned cpu)
@@ -316,7 +316,7 @@ irqreturn_t xen_debug_interrupt(int irq, void *dev_id) 
		       i % 8 == 0 ? "\n   " : " ");



	printk("\nlocal cpu%d mask:\n   ", cpu);

	for (i = (NR_EVENT_CHANNELS/BITS_PER_EVTCHN_WORD)-1; i >= 0; i--)

	for (i = (EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD)-1; i >= 0; i--)

		printk("%0*"PRI_xen_ulong"%s", (int)(sizeof(cpu_evtchn[0])*2),

		       cpu_evtchn[i],

		       i % 8 == 0 ? "\n   " : " ");
@@ -332,7 +332,7 @@ irqreturn_t xen_debug_interrupt(int irq, void *dev_id) 
	}



	printk("\npending list:\n");

	for (i = 0; i < NR_EVENT_CHANNELS; i++) {

	for (i = 0; i < EVTCHN_2L_NR_CHANNELS; i++) {

		if (sync_test_bit(i, BM(sh->evtchn_pending))) {

			int word_idx = i / BITS_PER_EVTCHN_WORD;

			printk("  %d: event %d -> irq %d%s%s%s\n",

include/xen/interface/event_channel.h

+68 −0
Original line number Diff line number Diff line
@@ -190,6 +190,39 @@ struct evtchn_reset { 
};

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 @@ struct evtchn_op { 
};

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__ */

include/xen/interface/xen.h

+0 −6
Original line number Diff line number Diff line
@@ -281,12 +281,6 @@ struct multicall_entry { 
};

DEFINE_GUEST_HANDLE_STRUCT(multicall_entry);



/*

 * Event channel endpoints per domain:

 *  1024 if a long is 32 bits; 4096 if a long is 64 bits.

 */

#define NR_EVENT_CHANNELS (sizeof(xen_ulong_t) * sizeof(xen_ulong_t) * 64)



struct vcpu_time_info {

	/*

	 * Updates to the following values are preceded and followed