Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 1 | /* Virtio ring implementation. |
| 2 | * |
| 3 | * Copyright 2007 Rusty Russell IBM Corporation |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License as published by |
| 7 | * the Free Software Foundation; either version 2 of the License, or |
| 8 | * (at your option) any later version. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this program; if not, write to the Free Software |
| 17 | * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
| 18 | */ |
| 19 | #include <linux/virtio.h> |
| 20 | #include <linux/virtio_ring.h> |
Rusty Russell | e34f872 | 2008-07-25 12:06:13 -0500 | [diff] [blame] | 21 | #include <linux/virtio_config.h> |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 22 | #include <linux/device.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 23 | #include <linux/slab.h> |
Paul Gortmaker | b5a2c4f | 2011-07-03 16:20:30 -0400 | [diff] [blame] | 24 | #include <linux/module.h> |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 25 | |
Michael S. Tsirkin | d57ed95 | 2010-01-28 00:42:23 +0200 | [diff] [blame] | 26 | /* virtio guest is communicating with a virtual "device" that actually runs on |
| 27 | * a host processor. Memory barriers are used to control SMP effects. */ |
| 28 | #ifdef CONFIG_SMP |
| 29 | /* Where possible, use SMP barriers which are more lightweight than mandatory |
| 30 | * barriers, because mandatory barriers control MMIO effects on accesses |
Rusty Russell | 7b21e34 | 2012-01-12 15:44:42 +1030 | [diff] [blame^] | 31 | * through relaxed memory I/O windows (which virtio-pci does not use). */ |
| 32 | #define virtio_mb(vq) \ |
| 33 | do { if ((vq)->weak_barriers) smp_mb(); else mb(); } while(0) |
| 34 | #define virtio_rmb(vq) \ |
| 35 | do { if ((vq)->weak_barriers) smp_rmb(); else rmb(); } while(0) |
| 36 | #define virtio_wmb(vq) \ |
| 37 | do { if ((vq)->weak_barriers) smp_rmb(); else rmb(); } while(0) |
Michael S. Tsirkin | d57ed95 | 2010-01-28 00:42:23 +0200 | [diff] [blame] | 38 | #else |
| 39 | /* We must force memory ordering even if guest is UP since host could be |
| 40 | * running on another CPU, but SMP barriers are defined to barrier() in that |
| 41 | * configuration. So fall back to mandatory barriers instead. */ |
Rusty Russell | 7b21e34 | 2012-01-12 15:44:42 +1030 | [diff] [blame^] | 42 | #define virtio_mb(vq) mb() |
| 43 | #define virtio_rmb(vq) rmb() |
| 44 | #define virtio_wmb(vq) wmb() |
Michael S. Tsirkin | d57ed95 | 2010-01-28 00:42:23 +0200 | [diff] [blame] | 45 | #endif |
| 46 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 47 | #ifdef DEBUG |
| 48 | /* For development, we want to crash whenever the ring is screwed. */ |
Rusty Russell | 9499f5e | 2009-06-12 22:16:35 -0600 | [diff] [blame] | 49 | #define BAD_RING(_vq, fmt, args...) \ |
| 50 | do { \ |
| 51 | dev_err(&(_vq)->vq.vdev->dev, \ |
| 52 | "%s:"fmt, (_vq)->vq.name, ##args); \ |
| 53 | BUG(); \ |
| 54 | } while (0) |
Rusty Russell | c5f841f | 2009-03-30 21:55:22 -0600 | [diff] [blame] | 55 | /* Caller is supposed to guarantee no reentry. */ |
| 56 | #define START_USE(_vq) \ |
| 57 | do { \ |
| 58 | if ((_vq)->in_use) \ |
Rusty Russell | 9499f5e | 2009-06-12 22:16:35 -0600 | [diff] [blame] | 59 | panic("%s:in_use = %i\n", \ |
| 60 | (_vq)->vq.name, (_vq)->in_use); \ |
Rusty Russell | c5f841f | 2009-03-30 21:55:22 -0600 | [diff] [blame] | 61 | (_vq)->in_use = __LINE__; \ |
Rusty Russell | 9499f5e | 2009-06-12 22:16:35 -0600 | [diff] [blame] | 62 | } while (0) |
Roel Kluin | 3a35ce7 | 2009-01-22 16:42:57 +0100 | [diff] [blame] | 63 | #define END_USE(_vq) \ |
Rusty Russell | 97a545a | 2010-02-24 14:22:22 -0600 | [diff] [blame] | 64 | do { BUG_ON(!(_vq)->in_use); (_vq)->in_use = 0; } while(0) |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 65 | #else |
Rusty Russell | 9499f5e | 2009-06-12 22:16:35 -0600 | [diff] [blame] | 66 | #define BAD_RING(_vq, fmt, args...) \ |
| 67 | do { \ |
| 68 | dev_err(&_vq->vq.vdev->dev, \ |
| 69 | "%s:"fmt, (_vq)->vq.name, ##args); \ |
| 70 | (_vq)->broken = true; \ |
| 71 | } while (0) |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 72 | #define START_USE(vq) |
| 73 | #define END_USE(vq) |
| 74 | #endif |
| 75 | |
| 76 | struct vring_virtqueue |
| 77 | { |
| 78 | struct virtqueue vq; |
| 79 | |
| 80 | /* Actual memory layout for this queue */ |
| 81 | struct vring vring; |
| 82 | |
Rusty Russell | 7b21e34 | 2012-01-12 15:44:42 +1030 | [diff] [blame^] | 83 | /* Can we use weak barriers? */ |
| 84 | bool weak_barriers; |
| 85 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 86 | /* Other side has made a mess, don't try any more. */ |
| 87 | bool broken; |
| 88 | |
Mark McLoughlin | 9fa29b9d | 2009-05-11 18:11:45 +0100 | [diff] [blame] | 89 | /* Host supports indirect buffers */ |
| 90 | bool indirect; |
| 91 | |
Michael S. Tsirkin | a5c262c | 2011-05-20 02:10:44 +0300 | [diff] [blame] | 92 | /* Host publishes avail event idx */ |
| 93 | bool event; |
| 94 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 95 | /* Number of free buffers */ |
| 96 | unsigned int num_free; |
| 97 | /* Head of free buffer list. */ |
| 98 | unsigned int free_head; |
| 99 | /* Number we've added since last sync. */ |
| 100 | unsigned int num_added; |
| 101 | |
| 102 | /* Last used index we've seen. */ |
Anthony Liguori | 1bc4953 | 2007-11-07 15:49:24 -0600 | [diff] [blame] | 103 | u16 last_used_idx; |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 104 | |
| 105 | /* How to notify other side. FIXME: commonalize hcalls! */ |
| 106 | void (*notify)(struct virtqueue *vq); |
| 107 | |
| 108 | #ifdef DEBUG |
| 109 | /* They're supposed to lock for us. */ |
| 110 | unsigned int in_use; |
| 111 | #endif |
| 112 | |
| 113 | /* Tokens for callbacks. */ |
| 114 | void *data[]; |
| 115 | }; |
| 116 | |
| 117 | #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq) |
| 118 | |
Mark McLoughlin | 9fa29b9d | 2009-05-11 18:11:45 +0100 | [diff] [blame] | 119 | /* Set up an indirect table of descriptors and add it to the queue. */ |
| 120 | static int vring_add_indirect(struct vring_virtqueue *vq, |
| 121 | struct scatterlist sg[], |
| 122 | unsigned int out, |
Michael S. Tsirkin | bbd603e | 2010-04-29 17:26:37 +0300 | [diff] [blame] | 123 | unsigned int in, |
| 124 | gfp_t gfp) |
Mark McLoughlin | 9fa29b9d | 2009-05-11 18:11:45 +0100 | [diff] [blame] | 125 | { |
| 126 | struct vring_desc *desc; |
| 127 | unsigned head; |
| 128 | int i; |
| 129 | |
Michael S. Tsirkin | bbd603e | 2010-04-29 17:26:37 +0300 | [diff] [blame] | 130 | desc = kmalloc((out + in) * sizeof(struct vring_desc), gfp); |
Mark McLoughlin | 9fa29b9d | 2009-05-11 18:11:45 +0100 | [diff] [blame] | 131 | if (!desc) |
Michael S. Tsirkin | 686d363 | 2010-06-10 18:16:11 +0300 | [diff] [blame] | 132 | return -ENOMEM; |
Mark McLoughlin | 9fa29b9d | 2009-05-11 18:11:45 +0100 | [diff] [blame] | 133 | |
| 134 | /* Transfer entries from the sg list into the indirect page */ |
| 135 | for (i = 0; i < out; i++) { |
| 136 | desc[i].flags = VRING_DESC_F_NEXT; |
| 137 | desc[i].addr = sg_phys(sg); |
| 138 | desc[i].len = sg->length; |
| 139 | desc[i].next = i+1; |
| 140 | sg++; |
| 141 | } |
| 142 | for (; i < (out + in); i++) { |
| 143 | desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE; |
| 144 | desc[i].addr = sg_phys(sg); |
| 145 | desc[i].len = sg->length; |
| 146 | desc[i].next = i+1; |
| 147 | sg++; |
| 148 | } |
| 149 | |
| 150 | /* Last one doesn't continue. */ |
| 151 | desc[i-1].flags &= ~VRING_DESC_F_NEXT; |
| 152 | desc[i-1].next = 0; |
| 153 | |
| 154 | /* We're about to use a buffer */ |
| 155 | vq->num_free--; |
| 156 | |
| 157 | /* Use a single buffer which doesn't continue */ |
| 158 | head = vq->free_head; |
| 159 | vq->vring.desc[head].flags = VRING_DESC_F_INDIRECT; |
| 160 | vq->vring.desc[head].addr = virt_to_phys(desc); |
| 161 | vq->vring.desc[head].len = i * sizeof(struct vring_desc); |
| 162 | |
| 163 | /* Update free pointer */ |
| 164 | vq->free_head = vq->vring.desc[head].next; |
| 165 | |
| 166 | return head; |
| 167 | } |
| 168 | |
Michael S. Tsirkin | bbd603e | 2010-04-29 17:26:37 +0300 | [diff] [blame] | 169 | int virtqueue_add_buf_gfp(struct virtqueue *_vq, |
| 170 | struct scatterlist sg[], |
| 171 | unsigned int out, |
| 172 | unsigned int in, |
| 173 | void *data, |
| 174 | gfp_t gfp) |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 175 | { |
| 176 | struct vring_virtqueue *vq = to_vvq(_vq); |
Michael S. Tsirkin | 1fe9b6f | 2010-07-26 16:55:30 +0930 | [diff] [blame] | 177 | unsigned int i, avail, uninitialized_var(prev); |
| 178 | int head; |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 179 | |
Mark McLoughlin | 9fa29b9d | 2009-05-11 18:11:45 +0100 | [diff] [blame] | 180 | START_USE(vq); |
| 181 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 182 | BUG_ON(data == NULL); |
Mark McLoughlin | 9fa29b9d | 2009-05-11 18:11:45 +0100 | [diff] [blame] | 183 | |
| 184 | /* If the host supports indirect descriptor tables, and we have multiple |
| 185 | * buffers, then go indirect. FIXME: tune this threshold */ |
| 186 | if (vq->indirect && (out + in) > 1 && vq->num_free) { |
Michael S. Tsirkin | bbd603e | 2010-04-29 17:26:37 +0300 | [diff] [blame] | 187 | head = vring_add_indirect(vq, sg, out, in, gfp); |
Michael S. Tsirkin | 1fe9b6f | 2010-07-26 16:55:30 +0930 | [diff] [blame] | 188 | if (likely(head >= 0)) |
Mark McLoughlin | 9fa29b9d | 2009-05-11 18:11:45 +0100 | [diff] [blame] | 189 | goto add_head; |
| 190 | } |
| 191 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 192 | BUG_ON(out + in > vq->vring.num); |
| 193 | BUG_ON(out + in == 0); |
| 194 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 195 | if (vq->num_free < out + in) { |
| 196 | pr_debug("Can't add buf len %i - avail = %i\n", |
| 197 | out + in, vq->num_free); |
Rusty Russell | 44653ea | 2008-07-25 12:06:04 -0500 | [diff] [blame] | 198 | /* FIXME: for historical reasons, we force a notify here if |
| 199 | * there are outgoing parts to the buffer. Presumably the |
| 200 | * host should service the ring ASAP. */ |
| 201 | if (out) |
| 202 | vq->notify(&vq->vq); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 203 | END_USE(vq); |
| 204 | return -ENOSPC; |
| 205 | } |
| 206 | |
| 207 | /* We're about to use some buffers from the free list. */ |
| 208 | vq->num_free -= out + in; |
| 209 | |
| 210 | head = vq->free_head; |
| 211 | for (i = vq->free_head; out; i = vq->vring.desc[i].next, out--) { |
| 212 | vq->vring.desc[i].flags = VRING_DESC_F_NEXT; |
Rusty Russell | 15f9c89 | 2008-02-04 23:50:05 -0500 | [diff] [blame] | 213 | vq->vring.desc[i].addr = sg_phys(sg); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 214 | vq->vring.desc[i].len = sg->length; |
| 215 | prev = i; |
| 216 | sg++; |
| 217 | } |
| 218 | for (; in; i = vq->vring.desc[i].next, in--) { |
| 219 | vq->vring.desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE; |
Rusty Russell | 15f9c89 | 2008-02-04 23:50:05 -0500 | [diff] [blame] | 220 | vq->vring.desc[i].addr = sg_phys(sg); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 221 | vq->vring.desc[i].len = sg->length; |
| 222 | prev = i; |
| 223 | sg++; |
| 224 | } |
| 225 | /* Last one doesn't continue. */ |
| 226 | vq->vring.desc[prev].flags &= ~VRING_DESC_F_NEXT; |
| 227 | |
| 228 | /* Update free pointer */ |
| 229 | vq->free_head = i; |
| 230 | |
Mark McLoughlin | 9fa29b9d | 2009-05-11 18:11:45 +0100 | [diff] [blame] | 231 | add_head: |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 232 | /* Set token. */ |
| 233 | vq->data[head] = data; |
| 234 | |
| 235 | /* Put entry in available array (but don't update avail->idx until they |
| 236 | * do sync). FIXME: avoid modulus here? */ |
| 237 | avail = (vq->vring.avail->idx + vq->num_added++) % vq->vring.num; |
| 238 | vq->vring.avail->ring[avail] = head; |
| 239 | |
| 240 | pr_debug("Added buffer head %i to %p\n", head, vq); |
| 241 | END_USE(vq); |
Rusty Russell | 3c1b27d | 2009-09-23 22:26:31 -0600 | [diff] [blame] | 242 | |
Rusty Russell | 3c1b27d | 2009-09-23 22:26:31 -0600 | [diff] [blame] | 243 | return vq->num_free; |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 244 | } |
Michael S. Tsirkin | bbd603e | 2010-04-29 17:26:37 +0300 | [diff] [blame] | 245 | EXPORT_SYMBOL_GPL(virtqueue_add_buf_gfp); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 246 | |
Michael S. Tsirkin | 7c5e9ed | 2010-04-12 16:19:07 +0300 | [diff] [blame] | 247 | void virtqueue_kick(struct virtqueue *_vq) |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 248 | { |
| 249 | struct vring_virtqueue *vq = to_vvq(_vq); |
Michael S. Tsirkin | a5c262c | 2011-05-20 02:10:44 +0300 | [diff] [blame] | 250 | u16 new, old; |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 251 | START_USE(vq); |
| 252 | /* Descriptors and available array need to be set before we expose the |
| 253 | * new available array entries. */ |
Rusty Russell | 7b21e34 | 2012-01-12 15:44:42 +1030 | [diff] [blame^] | 254 | virtio_wmb(vq); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 255 | |
Michael S. Tsirkin | a5c262c | 2011-05-20 02:10:44 +0300 | [diff] [blame] | 256 | old = vq->vring.avail->idx; |
| 257 | new = vq->vring.avail->idx = old + vq->num_added; |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 258 | vq->num_added = 0; |
| 259 | |
| 260 | /* Need to update avail index before checking if we should notify */ |
Rusty Russell | 7b21e34 | 2012-01-12 15:44:42 +1030 | [diff] [blame^] | 261 | virtio_mb(vq); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 262 | |
Michael S. Tsirkin | a5c262c | 2011-05-20 02:10:44 +0300 | [diff] [blame] | 263 | if (vq->event ? |
| 264 | vring_need_event(vring_avail_event(&vq->vring), new, old) : |
| 265 | !(vq->vring.used->flags & VRING_USED_F_NO_NOTIFY)) |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 266 | /* Prod other side to tell it about changes. */ |
| 267 | vq->notify(&vq->vq); |
| 268 | |
| 269 | END_USE(vq); |
| 270 | } |
Michael S. Tsirkin | 7c5e9ed | 2010-04-12 16:19:07 +0300 | [diff] [blame] | 271 | EXPORT_SYMBOL_GPL(virtqueue_kick); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 272 | |
| 273 | static void detach_buf(struct vring_virtqueue *vq, unsigned int head) |
| 274 | { |
| 275 | unsigned int i; |
| 276 | |
| 277 | /* Clear data ptr. */ |
| 278 | vq->data[head] = NULL; |
| 279 | |
| 280 | /* Put back on free list: find end */ |
| 281 | i = head; |
Mark McLoughlin | 9fa29b9d | 2009-05-11 18:11:45 +0100 | [diff] [blame] | 282 | |
| 283 | /* Free the indirect table */ |
| 284 | if (vq->vring.desc[i].flags & VRING_DESC_F_INDIRECT) |
| 285 | kfree(phys_to_virt(vq->vring.desc[i].addr)); |
| 286 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 287 | while (vq->vring.desc[i].flags & VRING_DESC_F_NEXT) { |
| 288 | i = vq->vring.desc[i].next; |
| 289 | vq->num_free++; |
| 290 | } |
| 291 | |
| 292 | vq->vring.desc[i].next = vq->free_head; |
| 293 | vq->free_head = head; |
| 294 | /* Plus final descriptor */ |
| 295 | vq->num_free++; |
| 296 | } |
| 297 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 298 | static inline bool more_used(const struct vring_virtqueue *vq) |
| 299 | { |
| 300 | return vq->last_used_idx != vq->vring.used->idx; |
| 301 | } |
| 302 | |
Michael S. Tsirkin | 7c5e9ed | 2010-04-12 16:19:07 +0300 | [diff] [blame] | 303 | void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len) |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 304 | { |
| 305 | struct vring_virtqueue *vq = to_vvq(_vq); |
| 306 | void *ret; |
| 307 | unsigned int i; |
| 308 | |
| 309 | START_USE(vq); |
| 310 | |
Rusty Russell | 5ef8275 | 2008-05-02 21:50:43 -0500 | [diff] [blame] | 311 | if (unlikely(vq->broken)) { |
| 312 | END_USE(vq); |
| 313 | return NULL; |
| 314 | } |
| 315 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 316 | if (!more_used(vq)) { |
| 317 | pr_debug("No more buffers in queue\n"); |
| 318 | END_USE(vq); |
| 319 | return NULL; |
| 320 | } |
| 321 | |
Michael S. Tsirkin | 2d61ba9 | 2009-10-25 15:28:53 +0200 | [diff] [blame] | 322 | /* Only get used array entries after they have been exposed by host. */ |
Rusty Russell | 7b21e34 | 2012-01-12 15:44:42 +1030 | [diff] [blame^] | 323 | virtio_rmb(vq); |
Michael S. Tsirkin | 2d61ba9 | 2009-10-25 15:28:53 +0200 | [diff] [blame] | 324 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 325 | i = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].id; |
| 326 | *len = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].len; |
| 327 | |
| 328 | if (unlikely(i >= vq->vring.num)) { |
| 329 | BAD_RING(vq, "id %u out of range\n", i); |
| 330 | return NULL; |
| 331 | } |
| 332 | if (unlikely(!vq->data[i])) { |
| 333 | BAD_RING(vq, "id %u is not a head!\n", i); |
| 334 | return NULL; |
| 335 | } |
| 336 | |
| 337 | /* detach_buf clears data, so grab it now. */ |
| 338 | ret = vq->data[i]; |
| 339 | detach_buf(vq, i); |
| 340 | vq->last_used_idx++; |
Michael S. Tsirkin | a5c262c | 2011-05-20 02:10:44 +0300 | [diff] [blame] | 341 | /* If we expect an interrupt for the next entry, tell host |
| 342 | * by writing event index and flush out the write before |
| 343 | * the read in the next get_buf call. */ |
| 344 | if (!(vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT)) { |
| 345 | vring_used_event(&vq->vring) = vq->last_used_idx; |
Rusty Russell | 7b21e34 | 2012-01-12 15:44:42 +1030 | [diff] [blame^] | 346 | virtio_mb(vq); |
Michael S. Tsirkin | a5c262c | 2011-05-20 02:10:44 +0300 | [diff] [blame] | 347 | } |
| 348 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 349 | END_USE(vq); |
| 350 | return ret; |
| 351 | } |
Michael S. Tsirkin | 7c5e9ed | 2010-04-12 16:19:07 +0300 | [diff] [blame] | 352 | EXPORT_SYMBOL_GPL(virtqueue_get_buf); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 353 | |
Michael S. Tsirkin | 7c5e9ed | 2010-04-12 16:19:07 +0300 | [diff] [blame] | 354 | void virtqueue_disable_cb(struct virtqueue *_vq) |
Rusty Russell | 18445c4 | 2008-02-04 23:49:57 -0500 | [diff] [blame] | 355 | { |
| 356 | struct vring_virtqueue *vq = to_vvq(_vq); |
| 357 | |
Rusty Russell | 18445c4 | 2008-02-04 23:49:57 -0500 | [diff] [blame] | 358 | vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT; |
Rusty Russell | 18445c4 | 2008-02-04 23:49:57 -0500 | [diff] [blame] | 359 | } |
Michael S. Tsirkin | 7c5e9ed | 2010-04-12 16:19:07 +0300 | [diff] [blame] | 360 | EXPORT_SYMBOL_GPL(virtqueue_disable_cb); |
Rusty Russell | 18445c4 | 2008-02-04 23:49:57 -0500 | [diff] [blame] | 361 | |
Michael S. Tsirkin | 7c5e9ed | 2010-04-12 16:19:07 +0300 | [diff] [blame] | 362 | bool virtqueue_enable_cb(struct virtqueue *_vq) |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 363 | { |
| 364 | struct vring_virtqueue *vq = to_vvq(_vq); |
| 365 | |
| 366 | START_USE(vq); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 367 | |
| 368 | /* We optimistically turn back on interrupts, then check if there was |
| 369 | * more to do. */ |
Michael S. Tsirkin | a5c262c | 2011-05-20 02:10:44 +0300 | [diff] [blame] | 370 | /* Depending on the VIRTIO_RING_F_EVENT_IDX feature, we need to |
| 371 | * either clear the flags bit or point the event index at the next |
| 372 | * entry. Always do both to keep code simple. */ |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 373 | vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; |
Michael S. Tsirkin | a5c262c | 2011-05-20 02:10:44 +0300 | [diff] [blame] | 374 | vring_used_event(&vq->vring) = vq->last_used_idx; |
Rusty Russell | 7b21e34 | 2012-01-12 15:44:42 +1030 | [diff] [blame^] | 375 | virtio_mb(vq); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 376 | if (unlikely(more_used(vq))) { |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 377 | END_USE(vq); |
| 378 | return false; |
| 379 | } |
| 380 | |
| 381 | END_USE(vq); |
| 382 | return true; |
| 383 | } |
Michael S. Tsirkin | 7c5e9ed | 2010-04-12 16:19:07 +0300 | [diff] [blame] | 384 | EXPORT_SYMBOL_GPL(virtqueue_enable_cb); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 385 | |
Michael S. Tsirkin | 7ab358c | 2011-05-20 02:11:14 +0300 | [diff] [blame] | 386 | bool virtqueue_enable_cb_delayed(struct virtqueue *_vq) |
| 387 | { |
| 388 | struct vring_virtqueue *vq = to_vvq(_vq); |
| 389 | u16 bufs; |
| 390 | |
| 391 | START_USE(vq); |
| 392 | |
| 393 | /* We optimistically turn back on interrupts, then check if there was |
| 394 | * more to do. */ |
| 395 | /* Depending on the VIRTIO_RING_F_USED_EVENT_IDX feature, we need to |
| 396 | * either clear the flags bit or point the event index at the next |
| 397 | * entry. Always do both to keep code simple. */ |
| 398 | vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; |
| 399 | /* TODO: tune this threshold */ |
| 400 | bufs = (u16)(vq->vring.avail->idx - vq->last_used_idx) * 3 / 4; |
| 401 | vring_used_event(&vq->vring) = vq->last_used_idx + bufs; |
Rusty Russell | 7b21e34 | 2012-01-12 15:44:42 +1030 | [diff] [blame^] | 402 | virtio_mb(vq); |
Michael S. Tsirkin | 7ab358c | 2011-05-20 02:11:14 +0300 | [diff] [blame] | 403 | if (unlikely((u16)(vq->vring.used->idx - vq->last_used_idx) > bufs)) { |
| 404 | END_USE(vq); |
| 405 | return false; |
| 406 | } |
| 407 | |
| 408 | END_USE(vq); |
| 409 | return true; |
| 410 | } |
| 411 | EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed); |
| 412 | |
Michael S. Tsirkin | 7c5e9ed | 2010-04-12 16:19:07 +0300 | [diff] [blame] | 413 | void *virtqueue_detach_unused_buf(struct virtqueue *_vq) |
Shirley Ma | c021eac | 2010-01-18 19:15:23 +0530 | [diff] [blame] | 414 | { |
| 415 | struct vring_virtqueue *vq = to_vvq(_vq); |
| 416 | unsigned int i; |
| 417 | void *buf; |
| 418 | |
| 419 | START_USE(vq); |
| 420 | |
| 421 | for (i = 0; i < vq->vring.num; i++) { |
| 422 | if (!vq->data[i]) |
| 423 | continue; |
| 424 | /* detach_buf clears data, so grab it now. */ |
| 425 | buf = vq->data[i]; |
| 426 | detach_buf(vq, i); |
Amit Shah | b3258ff | 2011-03-16 19:12:10 +0530 | [diff] [blame] | 427 | vq->vring.avail->idx--; |
Shirley Ma | c021eac | 2010-01-18 19:15:23 +0530 | [diff] [blame] | 428 | END_USE(vq); |
| 429 | return buf; |
| 430 | } |
| 431 | /* That should have freed everything. */ |
| 432 | BUG_ON(vq->num_free != vq->vring.num); |
| 433 | |
| 434 | END_USE(vq); |
| 435 | return NULL; |
| 436 | } |
Michael S. Tsirkin | 7c5e9ed | 2010-04-12 16:19:07 +0300 | [diff] [blame] | 437 | EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf); |
Shirley Ma | c021eac | 2010-01-18 19:15:23 +0530 | [diff] [blame] | 438 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 439 | irqreturn_t vring_interrupt(int irq, void *_vq) |
| 440 | { |
| 441 | struct vring_virtqueue *vq = to_vvq(_vq); |
| 442 | |
| 443 | if (!more_used(vq)) { |
| 444 | pr_debug("virtqueue interrupt with no work for %p\n", vq); |
| 445 | return IRQ_NONE; |
| 446 | } |
| 447 | |
| 448 | if (unlikely(vq->broken)) |
| 449 | return IRQ_HANDLED; |
| 450 | |
| 451 | pr_debug("virtqueue callback for %p (%p)\n", vq, vq->vq.callback); |
Rusty Russell | 18445c4 | 2008-02-04 23:49:57 -0500 | [diff] [blame] | 452 | if (vq->vq.callback) |
| 453 | vq->vq.callback(&vq->vq); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 454 | |
| 455 | return IRQ_HANDLED; |
| 456 | } |
Rusty Russell | c6fd470 | 2008-02-04 23:50:05 -0500 | [diff] [blame] | 457 | EXPORT_SYMBOL_GPL(vring_interrupt); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 458 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 459 | struct virtqueue *vring_new_virtqueue(unsigned int num, |
Rusty Russell | 87c7d57 | 2008-12-30 09:26:03 -0600 | [diff] [blame] | 460 | unsigned int vring_align, |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 461 | struct virtio_device *vdev, |
Rusty Russell | 7b21e34 | 2012-01-12 15:44:42 +1030 | [diff] [blame^] | 462 | bool weak_barriers, |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 463 | void *pages, |
| 464 | void (*notify)(struct virtqueue *), |
Rusty Russell | 9499f5e | 2009-06-12 22:16:35 -0600 | [diff] [blame] | 465 | void (*callback)(struct virtqueue *), |
| 466 | const char *name) |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 467 | { |
| 468 | struct vring_virtqueue *vq; |
| 469 | unsigned int i; |
| 470 | |
Rusty Russell | 42b36cc | 2007-11-12 13:39:18 +1100 | [diff] [blame] | 471 | /* We assume num is a power of 2. */ |
| 472 | if (num & (num - 1)) { |
| 473 | dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num); |
| 474 | return NULL; |
| 475 | } |
| 476 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 477 | vq = kmalloc(sizeof(*vq) + sizeof(void *)*num, GFP_KERNEL); |
| 478 | if (!vq) |
| 479 | return NULL; |
| 480 | |
Rusty Russell | 87c7d57 | 2008-12-30 09:26:03 -0600 | [diff] [blame] | 481 | vring_init(&vq->vring, num, pages, vring_align); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 482 | vq->vq.callback = callback; |
| 483 | vq->vq.vdev = vdev; |
Rusty Russell | 9499f5e | 2009-06-12 22:16:35 -0600 | [diff] [blame] | 484 | vq->vq.name = name; |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 485 | vq->notify = notify; |
Rusty Russell | 7b21e34 | 2012-01-12 15:44:42 +1030 | [diff] [blame^] | 486 | vq->weak_barriers = weak_barriers; |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 487 | vq->broken = false; |
| 488 | vq->last_used_idx = 0; |
| 489 | vq->num_added = 0; |
Rusty Russell | 9499f5e | 2009-06-12 22:16:35 -0600 | [diff] [blame] | 490 | list_add_tail(&vq->vq.list, &vdev->vqs); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 491 | #ifdef DEBUG |
| 492 | vq->in_use = false; |
| 493 | #endif |
| 494 | |
Mark McLoughlin | 9fa29b9d | 2009-05-11 18:11:45 +0100 | [diff] [blame] | 495 | vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC); |
Michael S. Tsirkin | a5c262c | 2011-05-20 02:10:44 +0300 | [diff] [blame] | 496 | vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX); |
Mark McLoughlin | 9fa29b9d | 2009-05-11 18:11:45 +0100 | [diff] [blame] | 497 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 498 | /* No callback? Tell other side not to bother us. */ |
| 499 | if (!callback) |
| 500 | vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT; |
| 501 | |
| 502 | /* Put everything in free lists. */ |
| 503 | vq->num_free = num; |
| 504 | vq->free_head = 0; |
Amit Shah | 3b87062 | 2010-02-12 10:32:14 +0530 | [diff] [blame] | 505 | for (i = 0; i < num-1; i++) { |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 506 | vq->vring.desc[i].next = i+1; |
Amit Shah | 3b87062 | 2010-02-12 10:32:14 +0530 | [diff] [blame] | 507 | vq->data[i] = NULL; |
| 508 | } |
| 509 | vq->data[i] = NULL; |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 510 | |
| 511 | return &vq->vq; |
| 512 | } |
Rusty Russell | c6fd470 | 2008-02-04 23:50:05 -0500 | [diff] [blame] | 513 | EXPORT_SYMBOL_GPL(vring_new_virtqueue); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 514 | |
| 515 | void vring_del_virtqueue(struct virtqueue *vq) |
| 516 | { |
Rusty Russell | 9499f5e | 2009-06-12 22:16:35 -0600 | [diff] [blame] | 517 | list_del(&vq->list); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 518 | kfree(to_vvq(vq)); |
| 519 | } |
Rusty Russell | c6fd470 | 2008-02-04 23:50:05 -0500 | [diff] [blame] | 520 | EXPORT_SYMBOL_GPL(vring_del_virtqueue); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 521 | |
Rusty Russell | e34f872 | 2008-07-25 12:06:13 -0500 | [diff] [blame] | 522 | /* Manipulates transport-specific feature bits. */ |
| 523 | void vring_transport_features(struct virtio_device *vdev) |
| 524 | { |
| 525 | unsigned int i; |
| 526 | |
| 527 | for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) { |
| 528 | switch (i) { |
Mark McLoughlin | 9fa29b9d | 2009-05-11 18:11:45 +0100 | [diff] [blame] | 529 | case VIRTIO_RING_F_INDIRECT_DESC: |
| 530 | break; |
Michael S. Tsirkin | a5c262c | 2011-05-20 02:10:44 +0300 | [diff] [blame] | 531 | case VIRTIO_RING_F_EVENT_IDX: |
| 532 | break; |
Rusty Russell | e34f872 | 2008-07-25 12:06:13 -0500 | [diff] [blame] | 533 | default: |
| 534 | /* We don't understand this bit. */ |
| 535 | clear_bit(i, vdev->features); |
| 536 | } |
| 537 | } |
| 538 | } |
| 539 | EXPORT_SYMBOL_GPL(vring_transport_features); |
| 540 | |
Rick Jones | 8f9f466 | 2011-10-19 08:10:59 +0000 | [diff] [blame] | 541 | /* return the size of the vring within the virtqueue */ |
| 542 | unsigned int virtqueue_get_vring_size(struct virtqueue *_vq) |
| 543 | { |
| 544 | |
| 545 | struct vring_virtqueue *vq = to_vvq(_vq); |
| 546 | |
| 547 | return vq->vring.num; |
| 548 | } |
| 549 | EXPORT_SYMBOL_GPL(virtqueue_get_vring_size); |
| 550 | |
Rusty Russell | c6fd470 | 2008-02-04 23:50:05 -0500 | [diff] [blame] | 551 | MODULE_LICENSE("GPL"); |