15821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#ifndef _UAPI_LINUX_VIRTIO_RING_H 25821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define _UAPI_LINUX_VIRTIO_RING_H 35821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* An interface for efficient virtio implementation, currently for use by KVM 45821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * and lguest, but hopefully others soon. Do NOT change this since it will 55821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * break existing servers and clients. 65821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * 75821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * This header is BSD licensed so anyone can use the definitions to implement 85821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * compatible drivers/servers. 95821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * 105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * Redistribution and use in source and binary forms, with or without 115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * modification, are permitted provided that the following conditions 125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * are met: 132a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) * 1. Redistributions of source code must retain the above copyright 142a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) * notice, this list of conditions and the following disclaimer. 155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * 2. Redistributions in binary form must reproduce the above copyright 165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * notice, this list of conditions and the following disclaimer in the 175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * documentation and/or other materials provided with the distribution. 18f2477e01787aa58f445919b809d89e252beef54fTorne (Richard Coles) * 3. Neither the name of IBM nor the names of its contributors 192a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) * may be used to endorse or promote products derived from this software 201320f92c476a1ad9d19dba2a48c72b75566198e9Primiano Tucci * without specific prior written permission. 215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND 225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 235d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles) * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24a3f7b4e666c476898878fa745f637129375cd889Ben Murdoch * ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE 255e3f23d412006dc4db4e659864679f29341e113fTorne (Richard Coles) * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26868fa2fe829687343ffae624259930155e16dbd8Torne (Richard Coles) * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 272385ea399aae016c0806a4f9ef3c9cfe3d2a39dfBen Murdoch * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * SUCH DAMAGE. 325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * 335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * Copyright Rusty Russell IBM Corporation 2007. */ 345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include <linux/types.h> 355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 36f2477e01787aa58f445919b809d89e252beef54fTorne (Richard Coles)/* This marks a buffer as continuing via the next field. */ 37f2477e01787aa58f445919b809d89e252beef54fTorne (Richard Coles)#define VRING_DESC_F_NEXT 1 38f2477e01787aa58f445919b809d89e252beef54fTorne (Richard Coles)/* This marks a buffer as write-only (otherwise read-only). */ 39f2477e01787aa58f445919b809d89e252beef54fTorne (Richard Coles)#define VRING_DESC_F_WRITE 2 405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* This means the buffer contains a list of buffer descriptors. */ 415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define VRING_DESC_F_INDIRECT 4 425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* The Host uses this in used->flags to advise the Guest: don't kick me when 445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * you add a buffer. It's unreliable, so it's simply an optimization. Guest 455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * will still kick if it's out of buffers. */ 465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define VRING_USED_F_NO_NOTIFY 1 475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* The Guest uses this in avail->flags to advise the Host: don't interrupt me 485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * when you consume a buffer. It's unreliable, so it's simply an 495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * optimization. */ 505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define VRING_AVAIL_F_NO_INTERRUPT 1 515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* We support indirect buffer descriptors */ 535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define VIRTIO_RING_F_INDIRECT_DESC 28 545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* The Guest publishes the used index for which it expects an interrupt 565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * at the end of the avail ring. Host should ignore the avail->flags field. */ 575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* The Host publishes the avail index for which it expects a kick 585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * at the end of the used ring. Guest should ignore the used->flags field. */ 595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define VIRTIO_RING_F_EVENT_IDX 29 605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Virtio ring descriptors: 16 bytes. These can chain together via "next". */ 625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct vring_desc { 635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* Address (guest-physical). */ 645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) __u64 addr; 655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* Length. */ 665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) __u32 len; 675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* The flags as indicated above. */ 685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) __u16 flags; 695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* We chain unused descriptors via this, too */ 705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) __u16 next; 715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct vring_avail { 745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) __u16 flags; 755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) __u16 idx; 765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) __u16 ring[]; 775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* u32 is used here for ids for padding reasons. */ 805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct vring_used_elem { 815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* Index of start of used descriptor chain. */ 825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) __u32 id; 835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* Total length of the descriptor chain which was used (written to) */ 84c2e0dbddbe15c98d52c4786dac06cb8952a8ae6dTorne (Richard Coles) __u32 len; 855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct vring_used { 882385ea399aae016c0806a4f9ef3c9cfe3d2a39dfBen Murdoch __u16 flags; 8958e6fbe4ee35d65e14b626c557d37565bf8ad179Ben Murdoch __u16 idx; 905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) struct vring_used_elem ring[]; 915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct vring { 945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int num; 955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) struct vring_desc *desc; 975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 982a99a7e74a7f215066514fe81d2bfa6639d9edddTorne (Richard Coles) struct vring_avail *avail; 99a3f6a49ab37290eeeb8db0f41ec0f1cb74a68be7Torne (Richard Coles) 1005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) struct vring_used *used; 1015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 1025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* The standard layout for the ring is a continuous chunk of memory which looks 1045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * like this. We assume num is a power of 2. 1055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * 1065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * struct vring 1075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * { 1085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * // The actual descriptors (16 bytes each) 1095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * struct vring_desc desc[num]; 1105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * 111a3f6a49ab37290eeeb8db0f41ec0f1cb74a68be7Torne (Richard Coles) * // A ring of available descriptor heads with free-running index. 1125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * __u16 avail_flags; 1132385ea399aae016c0806a4f9ef3c9cfe3d2a39dfBen Murdoch * __u16 avail_idx; 11458e6fbe4ee35d65e14b626c557d37565bf8ad179Ben Murdoch * __u16 available[num]; 1155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * __u16 used_event_idx; 1165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * 1175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * // Padding to the next align boundary. 1185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * char pad[]; 1195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * 1205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * // A ring of used descriptor heads with free-running index. 1215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * __u16 used_flags; 1225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * __u16 used_idx; 1235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * struct vring_used_elem used[num]; 1245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * __u16 avail_event_idx; 1255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * }; 1265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) */ 1275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* We publish the used event index at the end of the available ring, and vice 1285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * versa. They are at the end for backwards compatibility. */ 1295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define vring_used_event(vr) ((vr)->avail->ring[(vr)->num]) 1305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define vring_avail_event(vr) (*(__u16 *)&(vr)->used->ring[(vr)->num]) 1315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static inline void vring_init(struct vring *vr, unsigned int num, void *p, 1335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned long align) 1345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles){ 1355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) vr->num = num; 1365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) vr->desc = p; 1375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) vr->avail = p + num*sizeof(struct vring_desc); 1385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + sizeof(__u16) 1395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) + align-1) & ~(align - 1)); 1405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 1415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static inline unsigned vring_size(unsigned int num, unsigned long align) 1435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles){ 1445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (3 + num) 1455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) + align - 1) & ~(align - 1)) 1465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) + sizeof(__u16) * 3 + sizeof(struct vring_used_elem) * num; 1475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 1485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */ 1505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Assuming a given event_idx value from the other size, if 151f2477e01787aa58f445919b809d89e252beef54fTorne (Richard Coles) * we have just incremented index from old to new_idx, 1525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * should we trigger an event? */ 1535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 old) 1545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles){ 1555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* Note: Xen has similar logic for notification hold-off 1565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * in include/xen/interface/io/ring.h with req_event and req_prod 1575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * corresponding to event_idx + 1 and new_idx respectively. 1585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * Note also that req_event and req_prod in Xen start at 1, 1595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) * event indexes in virtio start at 0. */ 160f2477e01787aa58f445919b809d89e252beef54fTorne (Richard Coles) return (__u16)(new_idx - event_idx - 1) < (__u16)(new_idx - old); 1615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 1625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 163f2477e01787aa58f445919b809d89e252beef54fTorne (Richard Coles)#endif /* _UAPI_LINUX_VIRTIO_RING_H */ 1645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)