jcs.org
qemu with hax to log dma reads & writes
jcs.org/2018/11/12/vfio
1/*
2 * netmap access for qemu
3 *
4 * Copyright (c) 2012-2013 Luigi Rizzo
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24
25
26#include "qemu/osdep.h"
27#include <sys/ioctl.h>
28#include <net/if.h>
29#define NETMAP_WITH_LIBS
30#include <net/netmap.h>
31#include <net/netmap_user.h>
32
33#include "net/net.h"
34#include "net/tap.h"
35#include "clients.h"
36#include "sysemu/sysemu.h"
37#include "qemu/error-report.h"
38#include "qapi/error.h"
39#include "qemu/iov.h"
40#include "qemu/cutils.h"
41#include "qemu/main-loop.h"
42
43typedef struct NetmapState {
44 NetClientState nc;
45 struct nm_desc *nmd;
46 char ifname[IFNAMSIZ];
47 struct netmap_ring *tx;
48 struct netmap_ring *rx;
49 bool read_poll;
50 bool write_poll;
51 struct iovec iov[IOV_MAX];
52 int vnet_hdr_len; /* Current virtio-net header length. */
53} NetmapState;
54
55#ifndef __FreeBSD__
56#define pkt_copy bcopy
57#else
58/* A fast copy routine only for multiples of 64 bytes, non overlapped. */
59static inline void
60pkt_copy(const void *_src, void *_dst, int l)
61{
62 const uint64_t *src = _src;
63 uint64_t *dst = _dst;
64 if (unlikely(l >= 1024)) {
65 bcopy(src, dst, l);
66 return;
67 }
68 for (; l > 0; l -= 64) {
69 *dst++ = *src++;
70 *dst++ = *src++;
71 *dst++ = *src++;
72 *dst++ = *src++;
73 *dst++ = *src++;
74 *dst++ = *src++;
75 *dst++ = *src++;
76 *dst++ = *src++;
77 }
78}
79#endif /* __FreeBSD__ */
80
81/*
82 * Open a netmap device. We assume there is only one queue
83 * (which is the case for the VALE bridge).
84 */
85static struct nm_desc *netmap_open(const NetdevNetmapOptions *nm_opts,
86 Error **errp)
87{
88 struct nm_desc *nmd;
89 struct nmreq req;
90
91 memset(&req, 0, sizeof(req));
92
93 nmd = nm_open(nm_opts->ifname, &req, NETMAP_NO_TX_POLL,
94 NULL);
95 if (nmd == NULL) {
96 error_setg_errno(errp, errno, "Failed to nm_open() %s",
97 nm_opts->ifname);
98 return NULL;
99 }
100
101 return nmd;
102}
103
104static void netmap_send(void *opaque);
105static void netmap_writable(void *opaque);
106
107/* Set the event-loop handlers for the netmap backend. */
108static void netmap_update_fd_handler(NetmapState *s)
109{
110 qemu_set_fd_handler(s->nmd->fd,
111 s->read_poll ? netmap_send : NULL,
112 s->write_poll ? netmap_writable : NULL,
113 s);
114}
115
116/* Update the read handler. */
117static void netmap_read_poll(NetmapState *s, bool enable)
118{
119 if (s->read_poll != enable) { /* Do nothing if not changed. */
120 s->read_poll = enable;
121 netmap_update_fd_handler(s);
122 }
123}
124
125/* Update the write handler. */
126static void netmap_write_poll(NetmapState *s, bool enable)
127{
128 if (s->write_poll != enable) {
129 s->write_poll = enable;
130 netmap_update_fd_handler(s);
131 }
132}
133
134static void netmap_poll(NetClientState *nc, bool enable)
135{
136 NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
137
138 if (s->read_poll != enable || s->write_poll != enable) {
139 s->write_poll = enable;
140 s->read_poll = enable;
141 netmap_update_fd_handler(s);
142 }
143}
144
145/*
146 * The fd_write() callback, invoked if the fd is marked as
147 * writable after a poll. Unregister the handler and flush any
148 * buffered packets.
149 */
150static void netmap_writable(void *opaque)
151{
152 NetmapState *s = opaque;
153
154 netmap_write_poll(s, false);
155 qemu_flush_queued_packets(&s->nc);
156}
157
158static ssize_t netmap_receive_iov(NetClientState *nc,
159 const struct iovec *iov, int iovcnt)
160{
161 NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
162 struct netmap_ring *ring = s->tx;
163 unsigned int tail = ring->tail;
164 ssize_t totlen = 0;
165 uint32_t last;
166 uint32_t idx;
167 uint8_t *dst;
168 int j;
169 uint32_t i;
170
171 last = i = ring->head;
172
173 if (nm_ring_space(ring) < iovcnt) {
174 /* Not enough netmap slots. Tell the kernel that we have seen the new
175 * available slots (so that it notifies us again when it has more
176 * ones), but without publishing any new slots to be processed
177 * (e.g., we don't advance ring->head). */
178 ring->cur = tail;
179 netmap_write_poll(s, true);
180 return 0;
181 }
182
183 for (j = 0; j < iovcnt; j++) {
184 int iov_frag_size = iov[j].iov_len;
185 int offset = 0;
186 int nm_frag_size;
187
188 totlen += iov_frag_size;
189
190 /* Split each iovec fragment over more netmap slots, if
191 necessary. */
192 while (iov_frag_size) {
193 nm_frag_size = MIN(iov_frag_size, ring->nr_buf_size);
194
195 if (unlikely(i == tail)) {
196 /* We ran out of netmap slots while splitting the
197 iovec fragments. */
198 ring->cur = tail;
199 netmap_write_poll(s, true);
200 return 0;
201 }
202
203 idx = ring->slot[i].buf_idx;
204 dst = (uint8_t *)NETMAP_BUF(ring, idx);
205
206 ring->slot[i].len = nm_frag_size;
207 ring->slot[i].flags = NS_MOREFRAG;
208 pkt_copy(iov[j].iov_base + offset, dst, nm_frag_size);
209
210 last = i;
211 i = nm_ring_next(ring, i);
212
213 offset += nm_frag_size;
214 iov_frag_size -= nm_frag_size;
215 }
216 }
217 /* The last slot must not have NS_MOREFRAG set. */
218 ring->slot[last].flags &= ~NS_MOREFRAG;
219
220 /* Now update ring->head and ring->cur to publish the new slots and
221 * the new wakeup point. */
222 ring->head = ring->cur = i;
223
224 ioctl(s->nmd->fd, NIOCTXSYNC, NULL);
225
226 return totlen;
227}
228
229static ssize_t netmap_receive(NetClientState *nc,
230 const uint8_t *buf, size_t size)
231{
232 struct iovec iov;
233
234 iov.iov_base = (void *)buf;
235 iov.iov_len = size;
236
237 return netmap_receive_iov(nc, &iov, 1);
238}
239
240/* Complete a previous send (backend --> guest) and enable the
241 fd_read callback. */
242static void netmap_send_completed(NetClientState *nc, ssize_t len)
243{
244 NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
245
246 netmap_read_poll(s, true);
247}
248
249static void netmap_send(void *opaque)
250{
251 NetmapState *s = opaque;
252 struct netmap_ring *ring = s->rx;
253 unsigned int tail = ring->tail;
254
255 /* Keep sending while there are available slots in the netmap
256 RX ring and the forwarding path towards the peer is open. */
257 while (ring->head != tail) {
258 uint32_t i = ring->head;
259 uint32_t idx;
260 bool morefrag;
261 int iovcnt = 0;
262 int iovsize;
263
264 /* Get a (possibly multi-slot) packet. */
265 do {
266 idx = ring->slot[i].buf_idx;
267 morefrag = (ring->slot[i].flags & NS_MOREFRAG);
268 s->iov[iovcnt].iov_base = (void *)NETMAP_BUF(ring, idx);
269 s->iov[iovcnt].iov_len = ring->slot[i].len;
270 iovcnt++;
271 i = nm_ring_next(ring, i);
272 } while (i != tail && morefrag);
273
274 /* Advance ring->cur to tell the kernel that we have seen the slots. */
275 ring->cur = i;
276
277 if (unlikely(morefrag)) {
278 /* This is a truncated packet, so we can stop without releasing the
279 * incomplete slots by updating ring->head. We will hopefully
280 * re-read the complete packet the next time we are called. */
281 break;
282 }
283
284 iovsize = qemu_sendv_packet_async(&s->nc, s->iov, iovcnt,
285 netmap_send_completed);
286
287 /* Release the slots to the kernel. */
288 ring->head = i;
289
290 if (iovsize == 0) {
291 /* The peer does not receive anymore. Packet is queued, stop
292 * reading from the backend until netmap_send_completed(). */
293 netmap_read_poll(s, false);
294 break;
295 }
296 }
297}
298
299/* Flush and close. */
300static void netmap_cleanup(NetClientState *nc)
301{
302 NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
303
304 qemu_purge_queued_packets(nc);
305
306 netmap_poll(nc, false);
307 nm_close(s->nmd);
308 s->nmd = NULL;
309}
310
311/* Offloading manipulation support callbacks. */
312static int netmap_fd_set_vnet_hdr_len(NetmapState *s, int len)
313{
314 struct nmreq req;
315
316 /* Issue a NETMAP_BDG_VNET_HDR command to change the virtio-net header
317 * length for the netmap adapter associated to 's->ifname'.
318 */
319 memset(&req, 0, sizeof(req));
320 pstrcpy(req.nr_name, sizeof(req.nr_name), s->ifname);
321 req.nr_version = NETMAP_API;
322 req.nr_cmd = NETMAP_BDG_VNET_HDR;
323 req.nr_arg1 = len;
324
325 return ioctl(s->nmd->fd, NIOCREGIF, &req);
326}
327
328static bool netmap_has_vnet_hdr_len(NetClientState *nc, int len)
329{
330 NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
331 int prev_len = s->vnet_hdr_len;
332
333 /* Check that we can set the new length. */
334 if (netmap_fd_set_vnet_hdr_len(s, len)) {
335 return false;
336 }
337
338 /* Restore the previous length. */
339 if (netmap_fd_set_vnet_hdr_len(s, prev_len)) {
340 error_report("Failed to restore vnet-hdr length %d on %s: %s",
341 prev_len, s->ifname, strerror(errno));
342 abort();
343 }
344
345 return true;
346}
347
348/* A netmap interface that supports virtio-net headers always
349 * supports UFO, so we use this callback also for the has_ufo hook. */
350static bool netmap_has_vnet_hdr(NetClientState *nc)
351{
352 return netmap_has_vnet_hdr_len(nc, sizeof(struct virtio_net_hdr));
353}
354
355static void netmap_using_vnet_hdr(NetClientState *nc, bool enable)
356{
357}
358
359static void netmap_set_vnet_hdr_len(NetClientState *nc, int len)
360{
361 NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
362 int err;
363
364 err = netmap_fd_set_vnet_hdr_len(s, len);
365 if (err) {
366 error_report("Unable to set vnet-hdr length %d on %s: %s",
367 len, s->ifname, strerror(errno));
368 } else {
369 /* Keep track of the current length. */
370 s->vnet_hdr_len = len;
371 }
372}
373
374static void netmap_set_offload(NetClientState *nc, int csum, int tso4, int tso6,
375 int ecn, int ufo)
376{
377 NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
378
379 /* Setting a virtio-net header length greater than zero automatically
380 * enables the offloadings. */
381 if (!s->vnet_hdr_len) {
382 netmap_set_vnet_hdr_len(nc, sizeof(struct virtio_net_hdr));
383 }
384}
385
386/* NetClientInfo methods */
387static NetClientInfo net_netmap_info = {
388 .type = NET_CLIENT_DRIVER_NETMAP,
389 .size = sizeof(NetmapState),
390 .receive = netmap_receive,
391 .receive_iov = netmap_receive_iov,
392 .poll = netmap_poll,
393 .cleanup = netmap_cleanup,
394 .has_ufo = netmap_has_vnet_hdr,
395 .has_vnet_hdr = netmap_has_vnet_hdr,
396 .has_vnet_hdr_len = netmap_has_vnet_hdr_len,
397 .using_vnet_hdr = netmap_using_vnet_hdr,
398 .set_offload = netmap_set_offload,
399 .set_vnet_hdr_len = netmap_set_vnet_hdr_len,
400};
401
402/* The exported init function
403 *
404 * ... -net netmap,ifname="..."
405 */
406int net_init_netmap(const Netdev *netdev,
407 const char *name, NetClientState *peer, Error **errp)
408{
409 const NetdevNetmapOptions *netmap_opts = &netdev->u.netmap;
410 struct nm_desc *nmd;
411 NetClientState *nc;
412 Error *err = NULL;
413 NetmapState *s;
414
415 nmd = netmap_open(netmap_opts, &err);
416 if (err) {
417 error_propagate(errp, err);
418 return -1;
419 }
420 /* Create the object. */
421 nc = qemu_new_net_client(&net_netmap_info, peer, "netmap", name);
422 s = DO_UPCAST(NetmapState, nc, nc);
423 s->nmd = nmd;
424 s->tx = NETMAP_TXRING(nmd->nifp, 0);
425 s->rx = NETMAP_RXRING(nmd->nifp, 0);
426 s->vnet_hdr_len = 0;
427 pstrcpy(s->ifname, sizeof(s->ifname), netmap_opts->ifname);
428 netmap_read_poll(s, true); /* Initially only poll for reads. */
429
430 return 0;
431}
432