#ifndef _LINUX_VIRTIO_RING_H
#define _LINUX_VIRTIO_RING_H
-/* An interface for efficient virtio implementation, currently for use by KVM
- * and lguest, but hopefully others soon. Do NOT change this since it will
- * break existing servers and clients.
- *
- * This header is BSD licensed so anyone can use the definitions to implement
- * compatible drivers/servers.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. Neither the name of IBM nor the names of its contributors
- * may be used to endorse or promote products derived from this software
- * without specific prior written permission.
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- * Copyright Rusty Russell IBM Corporation 2007. */
-#include <linux/types.h>
-/* This marks a buffer as continuing via the next field. */
-#define VRING_DESC_F_NEXT 1
-/* This marks a buffer as write-only (otherwise read-only). */
-#define VRING_DESC_F_WRITE 2
-/* This means the buffer contains a list of buffer descriptors. */
-#define VRING_DESC_F_INDIRECT 4
-
-/* The Host uses this in used->flags to advise the Guest: don't kick me when
- * you add a buffer. It's unreliable, so it's simply an optimization. Guest
- * will still kick if it's out of buffers. */
-#define VRING_USED_F_NO_NOTIFY 1
-/* The Guest uses this in avail->flags to advise the Host: don't interrupt me
- * when you consume a buffer. It's unreliable, so it's simply an
- * optimization. */
-#define VRING_AVAIL_F_NO_INTERRUPT 1
-
-/* We support indirect buffer descriptors */
-#define VIRTIO_RING_F_INDIRECT_DESC 28
-
-/* The Guest publishes the used index for which it expects an interrupt
- * at the end of the avail ring. Host should ignore the avail->flags field. */
-/* The Host publishes the avail index for which it expects a kick
- * at the end of the used ring. Guest should ignore the used->flags field. */
-#define VIRTIO_RING_F_EVENT_IDX 29
-
-/* Virtio ring descriptors: 16 bytes. These can chain together via "next". */
-struct vring_desc {
- /* Address (guest-physical). */
- __u64 addr;
- /* Length. */
- __u32 len;
- /* The flags as indicated above. */
- __u16 flags;
- /* We chain unused descriptors via this, too */
- __u16 next;
-};
-
-struct vring_avail {
- __u16 flags;
- __u16 idx;
- __u16 ring[];
-};
-
-/* u32 is used here for ids for padding reasons. */
-struct vring_used_elem {
- /* Index of start of used descriptor chain. */
- __u32 id;
- /* Total length of the descriptor chain which was used (written to) */
- __u32 len;
-};
-
-struct vring_used {
- __u16 flags;
- __u16 idx;
- struct vring_used_elem ring[];
-};
-
-struct vring {
- unsigned int num;
-
- struct vring_desc *desc;
-
- struct vring_avail *avail;
-
- struct vring_used *used;
-};
-
-/* The standard layout for the ring is a continuous chunk of memory which looks
- * like this. We assume num is a power of 2.
- *
- * struct vring
- * {
- * // The actual descriptors (16 bytes each)
- * struct vring_desc desc[num];
- *
- * // A ring of available descriptor heads with free-running index.
- * __u16 avail_flags;
- * __u16 avail_idx;
- * __u16 available[num];
- * __u16 used_event_idx;
- *
- * // Padding to the next align boundary.
- * char pad[];
- *
- * // A ring of used descriptor heads with free-running index.
- * __u16 used_flags;
- * __u16 used_idx;
- * struct vring_used_elem used[num];
- * __u16 avail_event_idx;
- * };
- */
-/* We publish the used event index at the end of the available ring, and vice
- * versa. They are at the end for backwards compatibility. */
-#define vring_used_event(vr) ((vr)->avail->ring[(vr)->num])
-#define vring_avail_event(vr) (*(__u16 *)&(vr)->used->ring[(vr)->num])
-
-static inline void vring_init(struct vring *vr, unsigned int num, void *p,
- unsigned long align)
-{
- vr->num = num;
- vr->desc = p;
- vr->avail = p + num*sizeof(struct vring_desc);
- vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + sizeof(__u16)
- + align-1) & ~(align - 1));
-}
-
-static inline unsigned vring_size(unsigned int num, unsigned long align)
-{
- return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (3 + num)
- + align - 1) & ~(align - 1))
- + sizeof(__u16) * 3 + sizeof(struct vring_used_elem) * num;
-}
-
-/* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */
-/* Assuming a given event_idx value from the other size, if
- * we have just incremented index from old to new_idx,
- * should we trigger an event? */
-static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 old)
-{
- /* Note: Xen has similar logic for notification hold-off
- * in include/xen/interface/io/ring.h with req_event and req_prod
- * corresponding to event_idx + 1 and new_idx respectively.
- * Note also that req_event and req_prod in Xen start at 1,
- * event indexes in virtio start at 0. */
- return (__u16)(new_idx - event_idx - 1) < (__u16)(new_idx - old);
-}
-
-#ifdef __KERNEL__
#include <linux/irqreturn.h>
+#include <uapi/linux/virtio_ring.h>
+
struct virtio_device;
struct virtqueue;
void vring_transport_features(struct virtio_device *vdev);
irqreturn_t vring_interrupt(int irq, void *_vq);
-#endif /* __KERNEL__ */
#endif /* _LINUX_VIRTIO_RING_H */
projects / firefly-linux-kernel-4.4.55.git / blobdiff