[linux-2.6-block.git] / include / linux / virtio_ring.h

#ifndef _LINUX_VIRTIO_RING_H
#define _LINUX_VIRTIO_RING_H

#include <asm/barrier.h>
#include <linux/irqreturn.h>
#include <uapi/linux/virtio_ring.h>

/*
 * Barriers in virtio are tricky.  Non-SMP virtio guests can't assume
 * they're not on an SMP host system, so they need to assume real
 * barriers.  Non-SMP virtio hosts could skip the barriers, but does
 * anyone care?
 *
 * For virtio_pci on SMP, we don't need to order with respect to MMIO
 * accesses through relaxed memory I/O windows, so virt_mb() et al are
 * sufficient.
 *
 * For using virtio to talk to real devices (eg. other heterogeneous
 * CPUs) we do need real barriers.  In theory, we could be using both
 * kinds of virtio, so it's a runtime decision, and the branch is
 * actually quite cheap.
 */

static inline void virtio_mb(bool weak_barriers)
{
	if (weak_barriers)
		virt_mb();
	else
		mb();
}

static inline void virtio_rmb(bool weak_barriers)
{
	if (weak_barriers)
		virt_rmb();
	else
		rmb();
}

static inline void virtio_wmb(bool weak_barriers)
{
	if (weak_barriers)
		virt_wmb();
	else
		wmb();
}

static inline void virtio_store_mb(bool weak_barriers,
				   __virtio16 *p, __virtio16 v)
{
	if (weak_barriers) {
		virt_store_mb(*p, v);
	} else {
		WRITE_ONCE(*p, v);
		mb();
	}
}

struct virtio_device;
struct virtqueue;

/*
 * Creates a virtqueue and allocates the descriptor ring.  If
 * may_reduce_num is set, then this may allocate a smaller ring than
 * expected.  The caller should query virtqueue_get_ring_size to learn
 * the actual size of the ring.
 */
struct virtqueue *vring_create_virtqueue(unsigned int index,
					 unsigned int num,
					 unsigned int vring_align,
					 struct virtio_device *vdev,
					 bool weak_barriers,
					 bool may_reduce_num,
					 bool (*notify)(struct virtqueue *vq),
					 void (*callback)(struct virtqueue *vq),
					 const char *name);

/* Creates a virtqueue with a custom layout. */
struct virtqueue *__vring_new_virtqueue(unsigned int index,
					struct vring vring,
					struct virtio_device *vdev,
					bool weak_barriers,
					bool (*notify)(struct virtqueue *),
					void (*callback)(struct virtqueue *),
					const char *name);

/*
 * Creates a virtqueue with a standard layout but a caller-allocated
 * ring.
 */
struct virtqueue *vring_new_virtqueue(unsigned int index,
				      unsigned int num,
				      unsigned int vring_align,
				      struct virtio_device *vdev,
				      bool weak_barriers,
				      void *pages,
				      bool (*notify)(struct virtqueue *vq),
				      void (*callback)(struct virtqueue *vq),
				      const char *name);

/*
 * Destroys a virtqueue.  If created with vring_create_virtqueue, this
 * also frees the ring.
 */
void vring_del_virtqueue(struct virtqueue *vq);

/* Filter out transport-specific feature bits. */
void vring_transport_features(struct virtio_device *vdev);

irqreturn_t vring_interrupt(int irq, void *_vq);
#endif /* _LINUX_VIRTIO_RING_H */
Commit	Line	Data
	1	#ifndef _LINUX_VIRTIO_RING_H
	2	#define _LINUX_VIRTIO_RING_H
	3
	4	#include <asm/barrier.h>
	5	#include <linux/irqreturn.h>
	6	#include <uapi/linux/virtio_ring.h>
	7
	8	/*
	9	* Barriers in virtio are tricky. Non-SMP virtio guests can't assume
	10	* they're not on an SMP host system, so they need to assume real
	11	* barriers. Non-SMP virtio hosts could skip the barriers, but does
	12	* anyone care?
	13	*
	14	* For virtio_pci on SMP, we don't need to order with respect to MMIO
	15	* accesses through relaxed memory I/O windows, so virt_mb() et al are
	16	* sufficient.
	17	*
	18	* For using virtio to talk to real devices (eg. other heterogeneous
	19	* CPUs) we do need real barriers. In theory, we could be using both
	20	* kinds of virtio, so it's a runtime decision, and the branch is
	21	* actually quite cheap.
	22	*/
	23
	24	static inline void virtio_mb(bool weak_barriers)
	25	{
	26	if (weak_barriers)
	27	virt_mb();
	28	else
	29	mb();
	30	}
	31
	32	static inline void virtio_rmb(bool weak_barriers)
	33	{
	34	if (weak_barriers)
	35	virt_rmb();
	36	else
	37	rmb();
	38	}
	39
	40	static inline void virtio_wmb(bool weak_barriers)
	41	{
	42	if (weak_barriers)
	43	virt_wmb();
	44	else
	45	wmb();
	46	}
	47
	48	static inline void virtio_store_mb(bool weak_barriers,
	49	__virtio16 *p, __virtio16 v)
	50	{
	51	if (weak_barriers) {
	52	virt_store_mb(*p, v);
	53	} else {
	54	WRITE_ONCE(*p, v);
	55	mb();
	56	}
	57	}
	58
	59	struct virtio_device;
	60	struct virtqueue;
	61
	62	/*
	63	* Creates a virtqueue and allocates the descriptor ring. If
	64	* may_reduce_num is set, then this may allocate a smaller ring than
	65	* expected. The caller should query virtqueue_get_ring_size to learn
	66	* the actual size of the ring.
	67	*/
	68	struct virtqueue *vring_create_virtqueue(unsigned int index,
	69	unsigned int num,
	70	unsigned int vring_align,
	71	struct virtio_device *vdev,
	72	bool weak_barriers,
	73	bool may_reduce_num,
	74	bool (notify)(struct virtqueue vq),
	75	void (callback)(struct virtqueue vq),
	76	const char *name);
	77
	78	/* Creates a virtqueue with a custom layout. */
	79	struct virtqueue *__vring_new_virtqueue(unsigned int index,
	80	struct vring vring,
	81	struct virtio_device *vdev,
	82	bool weak_barriers,
	83	bool (notify)(struct virtqueue ),
	84	void (callback)(struct virtqueue ),
	85	const char *name);
	86
	87	/*
	88	* Creates a virtqueue with a standard layout but a caller-allocated
	89	* ring.
	90	*/
	91	struct virtqueue *vring_new_virtqueue(unsigned int index,
	92	unsigned int num,
	93	unsigned int vring_align,
	94	struct virtio_device *vdev,
	95	bool weak_barriers,
	96	void *pages,
	97	bool (notify)(struct virtqueue vq),
	98	void (callback)(struct virtqueue vq),
	99	const char *name);
	100
	101	/*
	102	* Destroys a virtqueue. If created with vring_create_virtqueue, this
	103	* also frees the ring.
	104	*/
	105	void vring_del_virtqueue(struct virtqueue *vq);
	106
	107	/* Filter out transport-specific feature bits. */
	108	void vring_transport_features(struct virtio_device *vdev);
	109
	110	irqreturn_t vring_interrupt(int irq, void *_vq);
	111	#endif /* _LINUX_VIRTIO_RING_H */