1 /*
2  * Back-end of the driver for virtual network devices. This portion of the
3  * driver exports a 'unified' network-device interface that can be accessed
4  * by any operating system that implements a compatible front end. A
5  * reference front-end implementation can be found in:
6  *  drivers/net/xen-netfront.c
7  *
8  * Copyright (c) 2002-2005, K A Fraser
9  *
10  * This program is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU General Public License version 2
12  * as published by the Free Software Foundation; or, when distributed
13  * separately from the Linux kernel or incorporated into other
14  * software packages, subject to the following license:
15  *
16  * Permission is hereby granted, free of charge, to any person obtaining a copy
17  * of this source file (the "Software"), to deal in the Software without
18  * restriction, including without limitation the rights to use, copy, modify,
19  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
20  * and to permit persons to whom the Software is furnished to do so, subject to
21  * the following conditions:
22  *
23  * The above copyright notice and this permission notice shall be included in
24  * all copies or substantial portions of the Software.
25  *
26  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
27  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
28  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
29  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
30  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
31  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
32  * IN THE SOFTWARE.
33  */
34 
35 #include "common.h"
36 
37 #include <linux/kthread.h>
38 #include <linux/if_vlan.h>
39 #include <linux/udp.h>
40 #include <linux/highmem.h>
41 
42 #include <net/tcp.h>
43 
44 #include <xen/xen.h>
45 #include <xen/events.h>
46 #include <xen/interface/memory.h>
47 #include <xen/page.h>
48 
49 #include <asm/xen/hypercall.h>
50 
51 /* Provide an option to disable split event channels at load time as
52  * event channels are limited resource. Split event channels are
53  * enabled by default.
54  */
55 bool separate_tx_rx_irq = true;
56 module_param(separate_tx_rx_irq, bool, 0644);
57 
58 /* The time that packets can stay on the guest Rx internal queue
59  * before they are dropped.
60  */
61 unsigned int rx_drain_timeout_msecs = 10000;
62 module_param(rx_drain_timeout_msecs, uint, 0444);
63 
64 /* The length of time before the frontend is considered unresponsive
65  * because it isn't providing Rx slots.
66  */
67 unsigned int rx_stall_timeout_msecs = 60000;
68 module_param(rx_stall_timeout_msecs, uint, 0444);
69 
70 #define MAX_QUEUES_DEFAULT 8
71 unsigned int xenvif_max_queues;
72 module_param_named(max_queues, xenvif_max_queues, uint, 0644);
73 MODULE_PARM_DESC(max_queues,
74 		 "Maximum number of queues per virtual interface");
75 
76 /*
77  * This is the maximum slots a skb can have. If a guest sends a skb
78  * which exceeds this limit it is considered malicious.
79  */
80 #define FATAL_SKB_SLOTS_DEFAULT 20
81 static unsigned int fatal_skb_slots = FATAL_SKB_SLOTS_DEFAULT;
82 module_param(fatal_skb_slots, uint, 0444);
83 
84 /* The amount to copy out of the first guest Tx slot into the skb's
85  * linear area.  If the first slot has more data, it will be mapped
86  * and put into the first frag.
87  *
88  * This is sized to avoid pulling headers from the frags for most
89  * TCP/IP packets.
90  */
91 #define XEN_NETBACK_TX_COPY_LEN 128
92 
93 /* This is the maximum number of flows in the hash cache. */
94 #define XENVIF_HASH_CACHE_SIZE_DEFAULT 64
95 unsigned int xenvif_hash_cache_size = XENVIF_HASH_CACHE_SIZE_DEFAULT;
96 module_param_named(hash_cache_size, xenvif_hash_cache_size, uint, 0644);
97 MODULE_PARM_DESC(hash_cache_size, "Number of flows in the hash cache");
98 
99 /* The module parameter tells that we have to put data
100  * for xen-netfront with the XDP_PACKET_HEADROOM offset
101  * needed for XDP processing
102  */
103 bool provides_xdp_headroom = true;
104 module_param(provides_xdp_headroom, bool, 0644);
105 
106 static void xenvif_idx_release(struct xenvif_queue *queue, u16 pending_idx,
107 			       u8 status);
108 
109 static void make_tx_response(struct xenvif_queue *queue,
110 			     struct xen_netif_tx_request *txp,
111 			     unsigned int extra_count,
112 			     s8       st);
113 static void push_tx_responses(struct xenvif_queue *queue);
114 
115 static inline int tx_work_todo(struct xenvif_queue *queue);
116 
117 static inline unsigned long idx_to_pfn(struct xenvif_queue *queue,
118 				       u16 idx)
119 {
120 	return page_to_pfn(queue->mmap_pages[idx]);
121 }
122 
123 static inline unsigned long idx_to_kaddr(struct xenvif_queue *queue,
124 					 u16 idx)
125 {
126 	return (unsigned long)pfn_to_kaddr(idx_to_pfn(queue, idx));
127 }
128 
129 #define callback_param(vif, pending_idx) \
130 	(vif->pending_tx_info[pending_idx].callback_struct)
131 
132 /* Find the containing VIF's structure from a pointer in pending_tx_info array
133  */
134 static inline struct xenvif_queue *ubuf_to_queue(const struct ubuf_info *ubuf)
135 {
136 	u16 pending_idx = ubuf->desc;
137 	struct pending_tx_info *temp =
138 		container_of(ubuf, struct pending_tx_info, callback_struct);
139 	return container_of(temp - pending_idx,
140 			    struct xenvif_queue,
141 			    pending_tx_info[0]);
142 }
143 
144 static u16 frag_get_pending_idx(skb_frag_t *frag)
145 {
146 	return (u16)skb_frag_off(frag);
147 }
148 
149 static void frag_set_pending_idx(skb_frag_t *frag, u16 pending_idx)
150 {
151 	skb_frag_off_set(frag, pending_idx);
152 }
153 
154 static inline pending_ring_idx_t pending_index(unsigned i)
155 {
156 	return i & (MAX_PENDING_REQS-1);
157 }
158 
159 void xenvif_kick_thread(struct xenvif_queue *queue)
160 {
161 	wake_up(&queue->wq);
162 }
163 
164 void xenvif_napi_schedule_or_enable_events(struct xenvif_queue *queue)
165 {
166 	int more_to_do;
167 
168 	RING_FINAL_CHECK_FOR_REQUESTS(&queue->tx, more_to_do);
169 
170 	if (more_to_do)
171 		napi_schedule(&queue->napi);
172 	else if (atomic_fetch_andnot(NETBK_TX_EOI | NETBK_COMMON_EOI,
173 				     &queue->eoi_pending) &
174 		 (NETBK_TX_EOI | NETBK_COMMON_EOI))
175 		xen_irq_lateeoi(queue->tx_irq, 0);
176 }
177 
178 static void tx_add_credit(struct xenvif_queue *queue)
179 {
180 	unsigned long max_burst, max_credit;
181 
182 	/*
183 	 * Allow a burst big enough to transmit a jumbo packet of up to 128kB.
184 	 * Otherwise the interface can seize up due to insufficient credit.
185 	 */
186 	max_burst = max(131072UL, queue->credit_bytes);
187 
188 	/* Take care that adding a new chunk of credit doesn't wrap to zero. */
189 	max_credit = queue->remaining_credit + queue->credit_bytes;
190 	if (max_credit < queue->remaining_credit)
191 		max_credit = ULONG_MAX; /* wrapped: clamp to ULONG_MAX */
192 
193 	queue->remaining_credit = min(max_credit, max_burst);
194 	queue->rate_limited = false;
195 }
196 
197 void xenvif_tx_credit_callback(struct timer_list *t)
198 {
199 	struct xenvif_queue *queue = from_timer(queue, t, credit_timeout);
200 	tx_add_credit(queue);
201 	xenvif_napi_schedule_or_enable_events(queue);
202 }
203 
204 static void xenvif_tx_err(struct xenvif_queue *queue,
205 			  struct xen_netif_tx_request *txp,
206 			  unsigned int extra_count, RING_IDX end)
207 {
208 	RING_IDX cons = queue->tx.req_cons;
209 	unsigned long flags;
210 
211 	do {
212 		spin_lock_irqsave(&queue->response_lock, flags);
213 		make_tx_response(queue, txp, extra_count, XEN_NETIF_RSP_ERROR);
214 		push_tx_responses(queue);
215 		spin_unlock_irqrestore(&queue->response_lock, flags);
216 		if (cons == end)
217 			break;
218 		RING_COPY_REQUEST(&queue->tx, cons++, txp);
219 		extra_count = 0; /* only the first frag can have extras */
220 	} while (1);
221 	queue->tx.req_cons = cons;
222 }
223 
224 static void xenvif_fatal_tx_err(struct xenvif *vif)
225 {
226 	netdev_err(vif->dev, "fatal error; disabling device\n");
227 	vif->disabled = true;
228 	/* Disable the vif from queue 0's kthread */
229 	if (vif->num_queues)
230 		xenvif_kick_thread(&vif->queues[0]);
231 }
232 
233 static int xenvif_count_requests(struct xenvif_queue *queue,
234 				 struct xen_netif_tx_request *first,
235 				 unsigned int extra_count,
236 				 struct xen_netif_tx_request *txp,
237 				 int work_to_do)
238 {
239 	RING_IDX cons = queue->tx.req_cons;
240 	int slots = 0;
241 	int drop_err = 0;
242 	int more_data;
243 
244 	if (!(first->flags & XEN_NETTXF_more_data))
245 		return 0;
246 
247 	do {
248 		struct xen_netif_tx_request dropped_tx = { 0 };
249 
250 		if (slots >= work_to_do) {
251 			netdev_err(queue->vif->dev,
252 				   "Asked for %d slots but exceeds this limit\n",
253 				   work_to_do);
254 			xenvif_fatal_tx_err(queue->vif);
255 			return -ENODATA;
256 		}
257 
258 		/* This guest is really using too many slots and
259 		 * considered malicious.
260 		 */
261 		if (unlikely(slots >= fatal_skb_slots)) {
262 			netdev_err(queue->vif->dev,
263 				   "Malicious frontend using %d slots, threshold %u\n",
264 				   slots, fatal_skb_slots);
265 			xenvif_fatal_tx_err(queue->vif);
266 			return -E2BIG;
267 		}
268 
269 		/* Xen network protocol had implicit dependency on
270 		 * MAX_SKB_FRAGS. XEN_NETBK_LEGACY_SLOTS_MAX is set to
271 		 * the historical MAX_SKB_FRAGS value 18 to honor the
272 		 * same behavior as before. Any packet using more than
273 		 * 18 slots but less than fatal_skb_slots slots is
274 		 * dropped
275 		 */
276 		if (!drop_err && slots >= XEN_NETBK_LEGACY_SLOTS_MAX) {
277 			if (net_ratelimit())
278 				netdev_dbg(queue->vif->dev,
279 					   "Too many slots (%d) exceeding limit (%d), dropping packet\n",
280 					   slots, XEN_NETBK_LEGACY_SLOTS_MAX);
281 			drop_err = -E2BIG;
282 		}
283 
284 		if (drop_err)
285 			txp = &dropped_tx;
286 
287 		RING_COPY_REQUEST(&queue->tx, cons + slots, txp);
288 
289 		/* If the guest submitted a frame >= 64 KiB then
290 		 * first->size overflowed and following slots will
291 		 * appear to be larger than the frame.
292 		 *
293 		 * This cannot be fatal error as there are buggy
294 		 * frontends that do this.
295 		 *
296 		 * Consume all slots and drop the packet.
297 		 */
298 		if (!drop_err && txp->size > first->size) {
299 			if (net_ratelimit())
300 				netdev_dbg(queue->vif->dev,
301 					   "Invalid tx request, slot size %u > remaining size %u\n",
302 					   txp->size, first->size);
303 			drop_err = -EIO;
304 		}
305 
306 		first->size -= txp->size;
307 		slots++;
308 
309 		if (unlikely((txp->offset + txp->size) > XEN_PAGE_SIZE)) {
310 			netdev_err(queue->vif->dev, "Cross page boundary, txp->offset: %u, size: %u\n",
311 				 txp->offset, txp->size);
312 			xenvif_fatal_tx_err(queue->vif);
313 			return -EINVAL;
314 		}
315 
316 		more_data = txp->flags & XEN_NETTXF_more_data;
317 
318 		if (!drop_err)
319 			txp++;
320 
321 	} while (more_data);
322 
323 	if (drop_err) {
324 		xenvif_tx_err(queue, first, extra_count, cons + slots);
325 		return drop_err;
326 	}
327 
328 	return slots;
329 }
330 
331 
332 struct xenvif_tx_cb {
333 	u16 pending_idx;
334 };
335 
336 #define XENVIF_TX_CB(skb) ((struct xenvif_tx_cb *)(skb)->cb)
337 
338 static inline void xenvif_tx_create_map_op(struct xenvif_queue *queue,
339 					   u16 pending_idx,
340 					   struct xen_netif_tx_request *txp,
341 					   unsigned int extra_count,
342 					   struct gnttab_map_grant_ref *mop)
343 {
344 	queue->pages_to_map[mop-queue->tx_map_ops] = queue->mmap_pages[pending_idx];
345 	gnttab_set_map_op(mop, idx_to_kaddr(queue, pending_idx),
346 			  GNTMAP_host_map | GNTMAP_readonly,
347 			  txp->gref, queue->vif->domid);
348 
349 	memcpy(&queue->pending_tx_info[pending_idx].req, txp,
350 	       sizeof(*txp));
351 	queue->pending_tx_info[pending_idx].extra_count = extra_count;
352 }
353 
354 static inline struct sk_buff *xenvif_alloc_skb(unsigned int size)
355 {
356 	struct sk_buff *skb =
357 		alloc_skb(size + NET_SKB_PAD + NET_IP_ALIGN,
358 			  GFP_ATOMIC | __GFP_NOWARN);
359 	if (unlikely(skb == NULL))
360 		return NULL;
361 
362 	/* Packets passed to netif_rx() must have some headroom. */
363 	skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
364 
365 	/* Initialize it here to avoid later surprises */
366 	skb_shinfo(skb)->destructor_arg = NULL;
367 
368 	return skb;
369 }
370 
371 static struct gnttab_map_grant_ref *xenvif_get_requests(struct xenvif_queue *queue,
372 							struct sk_buff *skb,
373 							struct xen_netif_tx_request *txp,
374 							struct gnttab_map_grant_ref *gop,
375 							unsigned int frag_overflow,
376 							struct sk_buff *nskb)
377 {
378 	struct skb_shared_info *shinfo = skb_shinfo(skb);
379 	skb_frag_t *frags = shinfo->frags;
380 	u16 pending_idx = XENVIF_TX_CB(skb)->pending_idx;
381 	int start;
382 	pending_ring_idx_t index;
383 	unsigned int nr_slots;
384 
385 	nr_slots = shinfo->nr_frags;
386 
387 	/* Skip first skb fragment if it is on same page as header fragment. */
388 	start = (frag_get_pending_idx(&shinfo->frags[0]) == pending_idx);
389 
390 	for (shinfo->nr_frags = start; shinfo->nr_frags < nr_slots;
391 	     shinfo->nr_frags++, txp++, gop++) {
392 		index = pending_index(queue->pending_cons++);
393 		pending_idx = queue->pending_ring[index];
394 		xenvif_tx_create_map_op(queue, pending_idx, txp, 0, gop);
395 		frag_set_pending_idx(&frags[shinfo->nr_frags], pending_idx);
396 	}
397 
398 	if (frag_overflow) {
399 
400 		shinfo = skb_shinfo(nskb);
401 		frags = shinfo->frags;
402 
403 		for (shinfo->nr_frags = 0; shinfo->nr_frags < frag_overflow;
404 		     shinfo->nr_frags++, txp++, gop++) {
405 			index = pending_index(queue->pending_cons++);
406 			pending_idx = queue->pending_ring[index];
407 			xenvif_tx_create_map_op(queue, pending_idx, txp, 0,
408 						gop);
409 			frag_set_pending_idx(&frags[shinfo->nr_frags],
410 					     pending_idx);
411 		}
412 
413 		skb_shinfo(skb)->frag_list = nskb;
414 	}
415 
416 	return gop;
417 }
418 
419 static inline void xenvif_grant_handle_set(struct xenvif_queue *queue,
420 					   u16 pending_idx,
421 					   grant_handle_t handle)
422 {
423 	if (unlikely(queue->grant_tx_handle[pending_idx] !=
424 		     NETBACK_INVALID_HANDLE)) {
425 		netdev_err(queue->vif->dev,
426 			   "Trying to overwrite active handle! pending_idx: 0x%x\n",
427 			   pending_idx);
428 		BUG();
429 	}
430 	queue->grant_tx_handle[pending_idx] = handle;
431 }
432 
433 static inline void xenvif_grant_handle_reset(struct xenvif_queue *queue,
434 					     u16 pending_idx)
435 {
436 	if (unlikely(queue->grant_tx_handle[pending_idx] ==
437 		     NETBACK_INVALID_HANDLE)) {
438 		netdev_err(queue->vif->dev,
439 			   "Trying to unmap invalid handle! pending_idx: 0x%x\n",
440 			   pending_idx);
441 		BUG();
442 	}
443 	queue->grant_tx_handle[pending_idx] = NETBACK_INVALID_HANDLE;
444 }
445 
446 static int xenvif_tx_check_gop(struct xenvif_queue *queue,
447 			       struct sk_buff *skb,
448 			       struct gnttab_map_grant_ref **gopp_map,
449 			       struct gnttab_copy **gopp_copy)
450 {
451 	struct gnttab_map_grant_ref *gop_map = *gopp_map;
452 	u16 pending_idx = XENVIF_TX_CB(skb)->pending_idx;
453 	/* This always points to the shinfo of the skb being checked, which
454 	 * could be either the first or the one on the frag_list
455 	 */
456 	struct skb_shared_info *shinfo = skb_shinfo(skb);
457 	/* If this is non-NULL, we are currently checking the frag_list skb, and
458 	 * this points to the shinfo of the first one
459 	 */
460 	struct skb_shared_info *first_shinfo = NULL;
461 	int nr_frags = shinfo->nr_frags;
462 	const bool sharedslot = nr_frags &&
463 				frag_get_pending_idx(&shinfo->frags[0]) == pending_idx;
464 	int i, err;
465 
466 	/* Check status of header. */
467 	err = (*gopp_copy)->status;
468 	if (unlikely(err)) {
469 		if (net_ratelimit())
470 			netdev_dbg(queue->vif->dev,
471 				   "Grant copy of header failed! status: %d pending_idx: %u ref: %u\n",
472 				   (*gopp_copy)->status,
473 				   pending_idx,
474 				   (*gopp_copy)->source.u.ref);
475 		/* The first frag might still have this slot mapped */
476 		if (!sharedslot)
477 			xenvif_idx_release(queue, pending_idx,
478 					   XEN_NETIF_RSP_ERROR);
479 	}
480 	(*gopp_copy)++;
481 
482 check_frags:
483 	for (i = 0; i < nr_frags; i++, gop_map++) {
484 		int j, newerr;
485 
486 		pending_idx = frag_get_pending_idx(&shinfo->frags[i]);
487 
488 		/* Check error status: if okay then remember grant handle. */
489 		newerr = gop_map->status;
490 
491 		if (likely(!newerr)) {
492 			xenvif_grant_handle_set(queue,
493 						pending_idx,
494 						gop_map->handle);
495 			/* Had a previous error? Invalidate this fragment. */
496 			if (unlikely(err)) {
497 				xenvif_idx_unmap(queue, pending_idx);
498 				/* If the mapping of the first frag was OK, but
499 				 * the header's copy failed, and they are
500 				 * sharing a slot, send an error
501 				 */
502 				if (i == 0 && !first_shinfo && sharedslot)
503 					xenvif_idx_release(queue, pending_idx,
504 							   XEN_NETIF_RSP_ERROR);
505 				else
506 					xenvif_idx_release(queue, pending_idx,
507 							   XEN_NETIF_RSP_OKAY);
508 			}
509 			continue;
510 		}
511 
512 		/* Error on this fragment: respond to client with an error. */
513 		if (net_ratelimit())
514 			netdev_dbg(queue->vif->dev,
515 				   "Grant map of %d. frag failed! status: %d pending_idx: %u ref: %u\n",
516 				   i,
517 				   gop_map->status,
518 				   pending_idx,
519 				   gop_map->ref);
520 
521 		xenvif_idx_release(queue, pending_idx, XEN_NETIF_RSP_ERROR);
522 
523 		/* Not the first error? Preceding frags already invalidated. */
524 		if (err)
525 			continue;
526 
527 		/* First error: if the header haven't shared a slot with the
528 		 * first frag, release it as well.
529 		 */
530 		if (!sharedslot)
531 			xenvif_idx_release(queue,
532 					   XENVIF_TX_CB(skb)->pending_idx,
533 					   XEN_NETIF_RSP_OKAY);
534 
535 		/* Invalidate preceding fragments of this skb. */
536 		for (j = 0; j < i; j++) {
537 			pending_idx = frag_get_pending_idx(&shinfo->frags[j]);
538 			xenvif_idx_unmap(queue, pending_idx);
539 			xenvif_idx_release(queue, pending_idx,
540 					   XEN_NETIF_RSP_OKAY);
541 		}
542 
543 		/* And if we found the error while checking the frag_list, unmap
544 		 * the first skb's frags
545 		 */
546 		if (first_shinfo) {
547 			for (j = 0; j < first_shinfo->nr_frags; j++) {
548 				pending_idx = frag_get_pending_idx(&first_shinfo->frags[j]);
549 				xenvif_idx_unmap(queue, pending_idx);
550 				xenvif_idx_release(queue, pending_idx,
551 						   XEN_NETIF_RSP_OKAY);
552 			}
553 		}
554 
555 		/* Remember the error: invalidate all subsequent fragments. */
556 		err = newerr;
557 	}
558 
559 	if (skb_has_frag_list(skb) && !first_shinfo) {
560 		first_shinfo = shinfo;
561 		shinfo = skb_shinfo(shinfo->frag_list);
562 		nr_frags = shinfo->nr_frags;
563 
564 		goto check_frags;
565 	}
566 
567 	*gopp_map = gop_map;
568 	return err;
569 }
570 
571 static void xenvif_fill_frags(struct xenvif_queue *queue, struct sk_buff *skb)
572 {
573 	struct skb_shared_info *shinfo = skb_shinfo(skb);
574 	int nr_frags = shinfo->nr_frags;
575 	int i;
576 	u16 prev_pending_idx = INVALID_PENDING_IDX;
577 
578 	for (i = 0; i < nr_frags; i++) {
579 		skb_frag_t *frag = shinfo->frags + i;
580 		struct xen_netif_tx_request *txp;
581 		struct page *page;
582 		u16 pending_idx;
583 
584 		pending_idx = frag_get_pending_idx(frag);
585 
586 		/* If this is not the first frag, chain it to the previous*/
587 		if (prev_pending_idx == INVALID_PENDING_IDX)
588 			skb_shinfo(skb)->destructor_arg =
589 				&callback_param(queue, pending_idx);
590 		else
591 			callback_param(queue, prev_pending_idx).ctx =
592 				&callback_param(queue, pending_idx);
593 
594 		callback_param(queue, pending_idx).ctx = NULL;
595 		prev_pending_idx = pending_idx;
596 
597 		txp = &queue->pending_tx_info[pending_idx].req;
598 		page = virt_to_page(idx_to_kaddr(queue, pending_idx));
599 		__skb_fill_page_desc(skb, i, page, txp->offset, txp->size);
600 		skb->len += txp->size;
601 		skb->data_len += txp->size;
602 		skb->truesize += txp->size;
603 
604 		/* Take an extra reference to offset network stack's put_page */
605 		get_page(queue->mmap_pages[pending_idx]);
606 	}
607 }
608 
609 static int xenvif_get_extras(struct xenvif_queue *queue,
610 			     struct xen_netif_extra_info *extras,
611 			     unsigned int *extra_count,
612 			     int work_to_do)
613 {
614 	struct xen_netif_extra_info extra;
615 	RING_IDX cons = queue->tx.req_cons;
616 
617 	do {
618 		if (unlikely(work_to_do-- <= 0)) {
619 			netdev_err(queue->vif->dev, "Missing extra info\n");
620 			xenvif_fatal_tx_err(queue->vif);
621 			return -EBADR;
622 		}
623 
624 		RING_COPY_REQUEST(&queue->tx, cons, &extra);
625 
626 		queue->tx.req_cons = ++cons;
627 		(*extra_count)++;
628 
629 		if (unlikely(!extra.type ||
630 			     extra.type >= XEN_NETIF_EXTRA_TYPE_MAX)) {
631 			netdev_err(queue->vif->dev,
632 				   "Invalid extra type: %d\n", extra.type);
633 			xenvif_fatal_tx_err(queue->vif);
634 			return -EINVAL;
635 		}
636 
637 		memcpy(&extras[extra.type - 1], &extra, sizeof(extra));
638 	} while (extra.flags & XEN_NETIF_EXTRA_FLAG_MORE);
639 
640 	return work_to_do;
641 }
642 
643 static int xenvif_set_skb_gso(struct xenvif *vif,
644 			      struct sk_buff *skb,
645 			      struct xen_netif_extra_info *gso)
646 {
647 	if (!gso->u.gso.size) {
648 		netdev_err(vif->dev, "GSO size must not be zero.\n");
649 		xenvif_fatal_tx_err(vif);
650 		return -EINVAL;
651 	}
652 
653 	switch (gso->u.gso.type) {
654 	case XEN_NETIF_GSO_TYPE_TCPV4:
655 		skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
656 		break;
657 	case XEN_NETIF_GSO_TYPE_TCPV6:
658 		skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
659 		break;
660 	default:
661 		netdev_err(vif->dev, "Bad GSO type %d.\n", gso->u.gso.type);
662 		xenvif_fatal_tx_err(vif);
663 		return -EINVAL;
664 	}
665 
666 	skb_shinfo(skb)->gso_size = gso->u.gso.size;
667 	/* gso_segs will be calculated later */
668 
669 	return 0;
670 }
671 
672 static int checksum_setup(struct xenvif_queue *queue, struct sk_buff *skb)
673 {
674 	bool recalculate_partial_csum = false;
675 
676 	/* A GSO SKB must be CHECKSUM_PARTIAL. However some buggy
677 	 * peers can fail to set NETRXF_csum_blank when sending a GSO
678 	 * frame. In this case force the SKB to CHECKSUM_PARTIAL and
679 	 * recalculate the partial checksum.
680 	 */
681 	if (skb->ip_summed != CHECKSUM_PARTIAL && skb_is_gso(skb)) {
682 		queue->stats.rx_gso_checksum_fixup++;
683 		skb->ip_summed = CHECKSUM_PARTIAL;
684 		recalculate_partial_csum = true;
685 	}
686 
687 	/* A non-CHECKSUM_PARTIAL SKB does not require setup. */
688 	if (skb->ip_summed != CHECKSUM_PARTIAL)
689 		return 0;
690 
691 	return skb_checksum_setup(skb, recalculate_partial_csum);
692 }
693 
694 static bool tx_credit_exceeded(struct xenvif_queue *queue, unsigned size)
695 {
696 	u64 now = get_jiffies_64();
697 	u64 next_credit = queue->credit_window_start +
698 		msecs_to_jiffies(queue->credit_usec / 1000);
699 
700 	/* Timer could already be pending in rare cases. */
701 	if (timer_pending(&queue->credit_timeout)) {
702 		queue->rate_limited = true;
703 		return true;
704 	}
705 
706 	/* Passed the point where we can replenish credit? */
707 	if (time_after_eq64(now, next_credit)) {
708 		queue->credit_window_start = now;
709 		tx_add_credit(queue);
710 	}
711 
712 	/* Still too big to send right now? Set a callback. */
713 	if (size > queue->remaining_credit) {
714 		mod_timer(&queue->credit_timeout,
715 			  next_credit);
716 		queue->credit_window_start = next_credit;
717 		queue->rate_limited = true;
718 
719 		return true;
720 	}
721 
722 	return false;
723 }
724 
725 /* No locking is required in xenvif_mcast_add/del() as they are
726  * only ever invoked from NAPI poll. An RCU list is used because
727  * xenvif_mcast_match() is called asynchronously, during start_xmit.
728  */
729 
730 static int xenvif_mcast_add(struct xenvif *vif, const u8 *addr)
731 {
732 	struct xenvif_mcast_addr *mcast;
733 
734 	if (vif->fe_mcast_count == XEN_NETBK_MCAST_MAX) {
735 		if (net_ratelimit())
736 			netdev_err(vif->dev,
737 				   "Too many multicast addresses\n");
738 		return -ENOSPC;
739 	}
740 
741 	mcast = kzalloc(sizeof(*mcast), GFP_ATOMIC);
742 	if (!mcast)
743 		return -ENOMEM;
744 
745 	ether_addr_copy(mcast->addr, addr);
746 	list_add_tail_rcu(&mcast->entry, &vif->fe_mcast_addr);
747 	vif->fe_mcast_count++;
748 
749 	return 0;
750 }
751 
752 static void xenvif_mcast_del(struct xenvif *vif, const u8 *addr)
753 {
754 	struct xenvif_mcast_addr *mcast;
755 
756 	list_for_each_entry_rcu(mcast, &vif->fe_mcast_addr, entry) {
757 		if (ether_addr_equal(addr, mcast->addr)) {
758 			--vif->fe_mcast_count;
759 			list_del_rcu(&mcast->entry);
760 			kfree_rcu(mcast, rcu);
761 			break;
762 		}
763 	}
764 }
765 
766 bool xenvif_mcast_match(struct xenvif *vif, const u8 *addr)
767 {
768 	struct xenvif_mcast_addr *mcast;
769 
770 	rcu_read_lock();
771 	list_for_each_entry_rcu(mcast, &vif->fe_mcast_addr, entry) {
772 		if (ether_addr_equal(addr, mcast->addr)) {
773 			rcu_read_unlock();
774 			return true;
775 		}
776 	}
777 	rcu_read_unlock();
778 
779 	return false;
780 }
781 
782 void xenvif_mcast_addr_list_free(struct xenvif *vif)
783 {
784 	/* No need for locking or RCU here. NAPI poll and TX queue
785 	 * are stopped.
786 	 */
787 	while (!list_empty(&vif->fe_mcast_addr)) {
788 		struct xenvif_mcast_addr *mcast;
789 
790 		mcast = list_first_entry(&vif->fe_mcast_addr,
791 					 struct xenvif_mcast_addr,
792 					 entry);
793 		--vif->fe_mcast_count;
794 		list_del(&mcast->entry);
795 		kfree(mcast);
796 	}
797 }
798 
799 static void xenvif_tx_build_gops(struct xenvif_queue *queue,
800 				     int budget,
801 				     unsigned *copy_ops,
802 				     unsigned *map_ops)
803 {
804 	struct gnttab_map_grant_ref *gop = queue->tx_map_ops;
805 	struct sk_buff *skb, *nskb;
806 	int ret;
807 	unsigned int frag_overflow;
808 
809 	while (skb_queue_len(&queue->tx_queue) < budget) {
810 		struct xen_netif_tx_request txreq;
811 		struct xen_netif_tx_request txfrags[XEN_NETBK_LEGACY_SLOTS_MAX];
812 		struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX-1];
813 		unsigned int extra_count;
814 		u16 pending_idx;
815 		RING_IDX idx;
816 		int work_to_do;
817 		unsigned int data_len;
818 		pending_ring_idx_t index;
819 
820 		if (queue->tx.sring->req_prod - queue->tx.req_cons >
821 		    XEN_NETIF_TX_RING_SIZE) {
822 			netdev_err(queue->vif->dev,
823 				   "Impossible number of requests. "
824 				   "req_prod %d, req_cons %d, size %ld\n",
825 				   queue->tx.sring->req_prod, queue->tx.req_cons,
826 				   XEN_NETIF_TX_RING_SIZE);
827 			xenvif_fatal_tx_err(queue->vif);
828 			break;
829 		}
830 
831 		work_to_do = XEN_RING_NR_UNCONSUMED_REQUESTS(&queue->tx);
832 		if (!work_to_do)
833 			break;
834 
835 		idx = queue->tx.req_cons;
836 		rmb(); /* Ensure that we see the request before we copy it. */
837 		RING_COPY_REQUEST(&queue->tx, idx, &txreq);
838 
839 		/* Credit-based scheduling. */
840 		if (txreq.size > queue->remaining_credit &&
841 		    tx_credit_exceeded(queue, txreq.size))
842 			break;
843 
844 		queue->remaining_credit -= txreq.size;
845 
846 		work_to_do--;
847 		queue->tx.req_cons = ++idx;
848 
849 		memset(extras, 0, sizeof(extras));
850 		extra_count = 0;
851 		if (txreq.flags & XEN_NETTXF_extra_info) {
852 			work_to_do = xenvif_get_extras(queue, extras,
853 						       &extra_count,
854 						       work_to_do);
855 			idx = queue->tx.req_cons;
856 			if (unlikely(work_to_do < 0))
857 				break;
858 		}
859 
860 		if (extras[XEN_NETIF_EXTRA_TYPE_MCAST_ADD - 1].type) {
861 			struct xen_netif_extra_info *extra;
862 
863 			extra = &extras[XEN_NETIF_EXTRA_TYPE_MCAST_ADD - 1];
864 			ret = xenvif_mcast_add(queue->vif, extra->u.mcast.addr);
865 
866 			make_tx_response(queue, &txreq, extra_count,
867 					 (ret == 0) ?
868 					 XEN_NETIF_RSP_OKAY :
869 					 XEN_NETIF_RSP_ERROR);
870 			push_tx_responses(queue);
871 			continue;
872 		}
873 
874 		if (extras[XEN_NETIF_EXTRA_TYPE_MCAST_DEL - 1].type) {
875 			struct xen_netif_extra_info *extra;
876 
877 			extra = &extras[XEN_NETIF_EXTRA_TYPE_MCAST_DEL - 1];
878 			xenvif_mcast_del(queue->vif, extra->u.mcast.addr);
879 
880 			make_tx_response(queue, &txreq, extra_count,
881 					 XEN_NETIF_RSP_OKAY);
882 			push_tx_responses(queue);
883 			continue;
884 		}
885 
886 		ret = xenvif_count_requests(queue, &txreq, extra_count,
887 					    txfrags, work_to_do);
888 		if (unlikely(ret < 0))
889 			break;
890 
891 		idx += ret;
892 
893 		if (unlikely(txreq.size < ETH_HLEN)) {
894 			netdev_dbg(queue->vif->dev,
895 				   "Bad packet size: %d\n", txreq.size);
896 			xenvif_tx_err(queue, &txreq, extra_count, idx);
897 			break;
898 		}
899 
900 		/* No crossing a page as the payload mustn't fragment. */
901 		if (unlikely((txreq.offset + txreq.size) > XEN_PAGE_SIZE)) {
902 			netdev_err(queue->vif->dev,
903 				   "txreq.offset: %u, size: %u, end: %lu\n",
904 				   txreq.offset, txreq.size,
905 				   (unsigned long)(txreq.offset&~XEN_PAGE_MASK) + txreq.size);
906 			xenvif_fatal_tx_err(queue->vif);
907 			break;
908 		}
909 
910 		index = pending_index(queue->pending_cons);
911 		pending_idx = queue->pending_ring[index];
912 
913 		data_len = (txreq.size > XEN_NETBACK_TX_COPY_LEN &&
914 			    ret < XEN_NETBK_LEGACY_SLOTS_MAX) ?
915 			XEN_NETBACK_TX_COPY_LEN : txreq.size;
916 
917 		skb = xenvif_alloc_skb(data_len);
918 		if (unlikely(skb == NULL)) {
919 			netdev_dbg(queue->vif->dev,
920 				   "Can't allocate a skb in start_xmit.\n");
921 			xenvif_tx_err(queue, &txreq, extra_count, idx);
922 			break;
923 		}
924 
925 		skb_shinfo(skb)->nr_frags = ret;
926 		if (data_len < txreq.size)
927 			skb_shinfo(skb)->nr_frags++;
928 		/* At this point shinfo->nr_frags is in fact the number of
929 		 * slots, which can be as large as XEN_NETBK_LEGACY_SLOTS_MAX.
930 		 */
931 		frag_overflow = 0;
932 		nskb = NULL;
933 		if (skb_shinfo(skb)->nr_frags > MAX_SKB_FRAGS) {
934 			frag_overflow = skb_shinfo(skb)->nr_frags - MAX_SKB_FRAGS;
935 			BUG_ON(frag_overflow > MAX_SKB_FRAGS);
936 			skb_shinfo(skb)->nr_frags = MAX_SKB_FRAGS;
937 			nskb = xenvif_alloc_skb(0);
938 			if (unlikely(nskb == NULL)) {
939 				skb_shinfo(skb)->nr_frags = 0;
940 				kfree_skb(skb);
941 				xenvif_tx_err(queue, &txreq, extra_count, idx);
942 				if (net_ratelimit())
943 					netdev_err(queue->vif->dev,
944 						   "Can't allocate the frag_list skb.\n");
945 				break;
946 			}
947 		}
948 
949 		if (extras[XEN_NETIF_EXTRA_TYPE_GSO - 1].type) {
950 			struct xen_netif_extra_info *gso;
951 			gso = &extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];
952 
953 			if (xenvif_set_skb_gso(queue->vif, skb, gso)) {
954 				/* Failure in xenvif_set_skb_gso is fatal. */
955 				skb_shinfo(skb)->nr_frags = 0;
956 				kfree_skb(skb);
957 				kfree_skb(nskb);
958 				break;
959 			}
960 		}
961 
962 		if (extras[XEN_NETIF_EXTRA_TYPE_HASH - 1].type) {
963 			struct xen_netif_extra_info *extra;
964 			enum pkt_hash_types type = PKT_HASH_TYPE_NONE;
965 
966 			extra = &extras[XEN_NETIF_EXTRA_TYPE_HASH - 1];
967 
968 			switch (extra->u.hash.type) {
969 			case _XEN_NETIF_CTRL_HASH_TYPE_IPV4:
970 			case _XEN_NETIF_CTRL_HASH_TYPE_IPV6:
971 				type = PKT_HASH_TYPE_L3;
972 				break;
973 
974 			case _XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP:
975 			case _XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP:
976 				type = PKT_HASH_TYPE_L4;
977 				break;
978 
979 			default:
980 				break;
981 			}
982 
983 			if (type != PKT_HASH_TYPE_NONE)
984 				skb_set_hash(skb,
985 					     *(u32 *)extra->u.hash.value,
986 					     type);
987 		}
988 
989 		XENVIF_TX_CB(skb)->pending_idx = pending_idx;
990 
991 		__skb_put(skb, data_len);
992 		queue->tx_copy_ops[*copy_ops].source.u.ref = txreq.gref;
993 		queue->tx_copy_ops[*copy_ops].source.domid = queue->vif->domid;
994 		queue->tx_copy_ops[*copy_ops].source.offset = txreq.offset;
995 
996 		queue->tx_copy_ops[*copy_ops].dest.u.gmfn =
997 			virt_to_gfn(skb->data);
998 		queue->tx_copy_ops[*copy_ops].dest.domid = DOMID_SELF;
999 		queue->tx_copy_ops[*copy_ops].dest.offset =
1000 			offset_in_page(skb->data) & ~XEN_PAGE_MASK;
1001 
1002 		queue->tx_copy_ops[*copy_ops].len = data_len;
1003 		queue->tx_copy_ops[*copy_ops].flags = GNTCOPY_source_gref;
1004 
1005 		(*copy_ops)++;
1006 
1007 		if (data_len < txreq.size) {
1008 			frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
1009 					     pending_idx);
1010 			xenvif_tx_create_map_op(queue, pending_idx, &txreq,
1011 						extra_count, gop);
1012 			gop++;
1013 		} else {
1014 			frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
1015 					     INVALID_PENDING_IDX);
1016 			memcpy(&queue->pending_tx_info[pending_idx].req,
1017 			       &txreq, sizeof(txreq));
1018 			queue->pending_tx_info[pending_idx].extra_count =
1019 				extra_count;
1020 		}
1021 
1022 		queue->pending_cons++;
1023 
1024 		gop = xenvif_get_requests(queue, skb, txfrags, gop,
1025 				          frag_overflow, nskb);
1026 
1027 		__skb_queue_tail(&queue->tx_queue, skb);
1028 
1029 		queue->tx.req_cons = idx;
1030 
1031 		if (((gop-queue->tx_map_ops) >= ARRAY_SIZE(queue->tx_map_ops)) ||
1032 		    (*copy_ops >= ARRAY_SIZE(queue->tx_copy_ops)))
1033 			break;
1034 	}
1035 
1036 	(*map_ops) = gop - queue->tx_map_ops;
1037 	return;
1038 }
1039 
1040 /* Consolidate skb with a frag_list into a brand new one with local pages on
1041  * frags. Returns 0 or -ENOMEM if can't allocate new pages.
1042  */
1043 static int xenvif_handle_frag_list(struct xenvif_queue *queue, struct sk_buff *skb)
1044 {
1045 	unsigned int offset = skb_headlen(skb);
1046 	skb_frag_t frags[MAX_SKB_FRAGS];
1047 	int i, f;
1048 	struct ubuf_info *uarg;
1049 	struct sk_buff *nskb = skb_shinfo(skb)->frag_list;
1050 
1051 	queue->stats.tx_zerocopy_sent += 2;
1052 	queue->stats.tx_frag_overflow++;
1053 
1054 	xenvif_fill_frags(queue, nskb);
1055 	/* Subtract frags size, we will correct it later */
1056 	skb->truesize -= skb->data_len;
1057 	skb->len += nskb->len;
1058 	skb->data_len += nskb->len;
1059 
1060 	/* create a brand new frags array and coalesce there */
1061 	for (i = 0; offset < skb->len; i++) {
1062 		struct page *page;
1063 		unsigned int len;
1064 
1065 		BUG_ON(i >= MAX_SKB_FRAGS);
1066 		page = alloc_page(GFP_ATOMIC);
1067 		if (!page) {
1068 			int j;
1069 			skb->truesize += skb->data_len;
1070 			for (j = 0; j < i; j++)
1071 				put_page(skb_frag_page(&frags[j]));
1072 			return -ENOMEM;
1073 		}
1074 
1075 		if (offset + PAGE_SIZE < skb->len)
1076 			len = PAGE_SIZE;
1077 		else
1078 			len = skb->len - offset;
1079 		if (skb_copy_bits(skb, offset, page_address(page), len))
1080 			BUG();
1081 
1082 		offset += len;
1083 		__skb_frag_set_page(&frags[i], page);
1084 		skb_frag_off_set(&frags[i], 0);
1085 		skb_frag_size_set(&frags[i], len);
1086 	}
1087 
1088 	/* Release all the original (foreign) frags. */
1089 	for (f = 0; f < skb_shinfo(skb)->nr_frags; f++)
1090 		skb_frag_unref(skb, f);
1091 	uarg = skb_shinfo(skb)->destructor_arg;
1092 	/* increase inflight counter to offset decrement in callback */
1093 	atomic_inc(&queue->inflight_packets);
1094 	uarg->callback(NULL, uarg, true);
1095 	skb_shinfo(skb)->destructor_arg = NULL;
1096 
1097 	/* Fill the skb with the new (local) frags. */
1098 	memcpy(skb_shinfo(skb)->frags, frags, i * sizeof(skb_frag_t));
1099 	skb_shinfo(skb)->nr_frags = i;
1100 	skb->truesize += i * PAGE_SIZE;
1101 
1102 	return 0;
1103 }
1104 
1105 static int xenvif_tx_submit(struct xenvif_queue *queue)
1106 {
1107 	struct gnttab_map_grant_ref *gop_map = queue->tx_map_ops;
1108 	struct gnttab_copy *gop_copy = queue->tx_copy_ops;
1109 	struct sk_buff *skb;
1110 	int work_done = 0;
1111 
1112 	while ((skb = __skb_dequeue(&queue->tx_queue)) != NULL) {
1113 		struct xen_netif_tx_request *txp;
1114 		u16 pending_idx;
1115 		unsigned data_len;
1116 
1117 		pending_idx = XENVIF_TX_CB(skb)->pending_idx;
1118 		txp = &queue->pending_tx_info[pending_idx].req;
1119 
1120 		/* Check the remap error code. */
1121 		if (unlikely(xenvif_tx_check_gop(queue, skb, &gop_map, &gop_copy))) {
1122 			/* If there was an error, xenvif_tx_check_gop is
1123 			 * expected to release all the frags which were mapped,
1124 			 * so kfree_skb shouldn't do it again
1125 			 */
1126 			skb_shinfo(skb)->nr_frags = 0;
1127 			if (skb_has_frag_list(skb)) {
1128 				struct sk_buff *nskb =
1129 						skb_shinfo(skb)->frag_list;
1130 				skb_shinfo(nskb)->nr_frags = 0;
1131 			}
1132 			kfree_skb(skb);
1133 			continue;
1134 		}
1135 
1136 		data_len = skb->len;
1137 		callback_param(queue, pending_idx).ctx = NULL;
1138 		if (data_len < txp->size) {
1139 			/* Append the packet payload as a fragment. */
1140 			txp->offset += data_len;
1141 			txp->size -= data_len;
1142 		} else {
1143 			/* Schedule a response immediately. */
1144 			xenvif_idx_release(queue, pending_idx,
1145 					   XEN_NETIF_RSP_OKAY);
1146 		}
1147 
1148 		if (txp->flags & XEN_NETTXF_csum_blank)
1149 			skb->ip_summed = CHECKSUM_PARTIAL;
1150 		else if (txp->flags & XEN_NETTXF_data_validated)
1151 			skb->ip_summed = CHECKSUM_UNNECESSARY;
1152 
1153 		xenvif_fill_frags(queue, skb);
1154 
1155 		if (unlikely(skb_has_frag_list(skb))) {
1156 			struct sk_buff *nskb = skb_shinfo(skb)->frag_list;
1157 			xenvif_skb_zerocopy_prepare(queue, nskb);
1158 			if (xenvif_handle_frag_list(queue, skb)) {
1159 				if (net_ratelimit())
1160 					netdev_err(queue->vif->dev,
1161 						   "Not enough memory to consolidate frag_list!\n");
1162 				xenvif_skb_zerocopy_prepare(queue, skb);
1163 				kfree_skb(skb);
1164 				continue;
1165 			}
1166 			/* Copied all the bits from the frag list -- free it. */
1167 			skb_frag_list_init(skb);
1168 			kfree_skb(nskb);
1169 		}
1170 
1171 		skb->dev      = queue->vif->dev;
1172 		skb->protocol = eth_type_trans(skb, skb->dev);
1173 		skb_reset_network_header(skb);
1174 
1175 		if (checksum_setup(queue, skb)) {
1176 			netdev_dbg(queue->vif->dev,
1177 				   "Can't setup checksum in net_tx_action\n");
1178 			/* We have to set this flag to trigger the callback */
1179 			if (skb_shinfo(skb)->destructor_arg)
1180 				xenvif_skb_zerocopy_prepare(queue, skb);
1181 			kfree_skb(skb);
1182 			continue;
1183 		}
1184 
1185 		skb_probe_transport_header(skb);
1186 
1187 		/* If the packet is GSO then we will have just set up the
1188 		 * transport header offset in checksum_setup so it's now
1189 		 * straightforward to calculate gso_segs.
1190 		 */
1191 		if (skb_is_gso(skb)) {
1192 			int mss, hdrlen;
1193 
1194 			/* GSO implies having the L4 header. */
1195 			WARN_ON_ONCE(!skb_transport_header_was_set(skb));
1196 			if (unlikely(!skb_transport_header_was_set(skb))) {
1197 				kfree_skb(skb);
1198 				continue;
1199 			}
1200 
1201 			mss = skb_shinfo(skb)->gso_size;
1202 			hdrlen = skb_transport_header(skb) -
1203 				skb_mac_header(skb) +
1204 				tcp_hdrlen(skb);
1205 
1206 			skb_shinfo(skb)->gso_segs =
1207 				DIV_ROUND_UP(skb->len - hdrlen, mss);
1208 		}
1209 
1210 		queue->stats.rx_bytes += skb->len;
1211 		queue->stats.rx_packets++;
1212 
1213 		work_done++;
1214 
1215 		/* Set this flag right before netif_receive_skb, otherwise
1216 		 * someone might think this packet already left netback, and
1217 		 * do a skb_copy_ubufs while we are still in control of the
1218 		 * skb. E.g. the __pskb_pull_tail earlier can do such thing.
1219 		 */
1220 		if (skb_shinfo(skb)->destructor_arg) {
1221 			xenvif_skb_zerocopy_prepare(queue, skb);
1222 			queue->stats.tx_zerocopy_sent++;
1223 		}
1224 
1225 		netif_receive_skb(skb);
1226 	}
1227 
1228 	return work_done;
1229 }
1230 
1231 void xenvif_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *ubuf,
1232 			      bool zerocopy_success)
1233 {
1234 	unsigned long flags;
1235 	pending_ring_idx_t index;
1236 	struct xenvif_queue *queue = ubuf_to_queue(ubuf);
1237 
1238 	/* This is the only place where we grab this lock, to protect callbacks
1239 	 * from each other.
1240 	 */
1241 	spin_lock_irqsave(&queue->callback_lock, flags);
1242 	do {
1243 		u16 pending_idx = ubuf->desc;
1244 		ubuf = (struct ubuf_info *) ubuf->ctx;
1245 		BUG_ON(queue->dealloc_prod - queue->dealloc_cons >=
1246 			MAX_PENDING_REQS);
1247 		index = pending_index(queue->dealloc_prod);
1248 		queue->dealloc_ring[index] = pending_idx;
1249 		/* Sync with xenvif_tx_dealloc_action:
1250 		 * insert idx then incr producer.
1251 		 */
1252 		smp_wmb();
1253 		queue->dealloc_prod++;
1254 	} while (ubuf);
1255 	spin_unlock_irqrestore(&queue->callback_lock, flags);
1256 
1257 	if (likely(zerocopy_success))
1258 		queue->stats.tx_zerocopy_success++;
1259 	else
1260 		queue->stats.tx_zerocopy_fail++;
1261 	xenvif_skb_zerocopy_complete(queue);
1262 }
1263 
1264 static inline void xenvif_tx_dealloc_action(struct xenvif_queue *queue)
1265 {
1266 	struct gnttab_unmap_grant_ref *gop;
1267 	pending_ring_idx_t dc, dp;
1268 	u16 pending_idx, pending_idx_release[MAX_PENDING_REQS];
1269 	unsigned int i = 0;
1270 
1271 	dc = queue->dealloc_cons;
1272 	gop = queue->tx_unmap_ops;
1273 
1274 	/* Free up any grants we have finished using */
1275 	do {
1276 		dp = queue->dealloc_prod;
1277 
1278 		/* Ensure we see all indices enqueued by all
1279 		 * xenvif_zerocopy_callback().
1280 		 */
1281 		smp_rmb();
1282 
1283 		while (dc != dp) {
1284 			BUG_ON(gop - queue->tx_unmap_ops >= MAX_PENDING_REQS);
1285 			pending_idx =
1286 				queue->dealloc_ring[pending_index(dc++)];
1287 
1288 			pending_idx_release[gop - queue->tx_unmap_ops] =
1289 				pending_idx;
1290 			queue->pages_to_unmap[gop - queue->tx_unmap_ops] =
1291 				queue->mmap_pages[pending_idx];
1292 			gnttab_set_unmap_op(gop,
1293 					    idx_to_kaddr(queue, pending_idx),
1294 					    GNTMAP_host_map,
1295 					    queue->grant_tx_handle[pending_idx]);
1296 			xenvif_grant_handle_reset(queue, pending_idx);
1297 			++gop;
1298 		}
1299 
1300 	} while (dp != queue->dealloc_prod);
1301 
1302 	queue->dealloc_cons = dc;
1303 
1304 	if (gop - queue->tx_unmap_ops > 0) {
1305 		int ret;
1306 		ret = gnttab_unmap_refs(queue->tx_unmap_ops,
1307 					NULL,
1308 					queue->pages_to_unmap,
1309 					gop - queue->tx_unmap_ops);
1310 		if (ret) {
1311 			netdev_err(queue->vif->dev, "Unmap fail: nr_ops %tu ret %d\n",
1312 				   gop - queue->tx_unmap_ops, ret);
1313 			for (i = 0; i < gop - queue->tx_unmap_ops; ++i) {
1314 				if (gop[i].status != GNTST_okay)
1315 					netdev_err(queue->vif->dev,
1316 						   " host_addr: 0x%llx handle: 0x%x status: %d\n",
1317 						   gop[i].host_addr,
1318 						   gop[i].handle,
1319 						   gop[i].status);
1320 			}
1321 			BUG();
1322 		}
1323 	}
1324 
1325 	for (i = 0; i < gop - queue->tx_unmap_ops; ++i)
1326 		xenvif_idx_release(queue, pending_idx_release[i],
1327 				   XEN_NETIF_RSP_OKAY);
1328 }
1329 
1330 
1331 /* Called after netfront has transmitted */
1332 int xenvif_tx_action(struct xenvif_queue *queue, int budget)
1333 {
1334 	unsigned nr_mops, nr_cops = 0;
1335 	int work_done, ret;
1336 
1337 	if (unlikely(!tx_work_todo(queue)))
1338 		return 0;
1339 
1340 	xenvif_tx_build_gops(queue, budget, &nr_cops, &nr_mops);
1341 
1342 	if (nr_cops == 0)
1343 		return 0;
1344 
1345 	gnttab_batch_copy(queue->tx_copy_ops, nr_cops);
1346 	if (nr_mops != 0) {
1347 		ret = gnttab_map_refs(queue->tx_map_ops,
1348 				      NULL,
1349 				      queue->pages_to_map,
1350 				      nr_mops);
1351 		if (ret) {
1352 			unsigned int i;
1353 
1354 			netdev_err(queue->vif->dev, "Map fail: nr %u ret %d\n",
1355 				   nr_mops, ret);
1356 			for (i = 0; i < nr_mops; ++i)
1357 				WARN_ON_ONCE(queue->tx_map_ops[i].status ==
1358 				             GNTST_okay);
1359 		}
1360 	}
1361 
1362 	work_done = xenvif_tx_submit(queue);
1363 
1364 	return work_done;
1365 }
1366 
1367 static void xenvif_idx_release(struct xenvif_queue *queue, u16 pending_idx,
1368 			       u8 status)
1369 {
1370 	struct pending_tx_info *pending_tx_info;
1371 	pending_ring_idx_t index;
1372 	unsigned long flags;
1373 
1374 	pending_tx_info = &queue->pending_tx_info[pending_idx];
1375 
1376 	spin_lock_irqsave(&queue->response_lock, flags);
1377 
1378 	make_tx_response(queue, &pending_tx_info->req,
1379 			 pending_tx_info->extra_count, status);
1380 
1381 	/* Release the pending index before pusing the Tx response so
1382 	 * its available before a new Tx request is pushed by the
1383 	 * frontend.
1384 	 */
1385 	index = pending_index(queue->pending_prod++);
1386 	queue->pending_ring[index] = pending_idx;
1387 
1388 	push_tx_responses(queue);
1389 
1390 	spin_unlock_irqrestore(&queue->response_lock, flags);
1391 }
1392 
1393 
1394 static void make_tx_response(struct xenvif_queue *queue,
1395 			     struct xen_netif_tx_request *txp,
1396 			     unsigned int extra_count,
1397 			     s8       st)
1398 {
1399 	RING_IDX i = queue->tx.rsp_prod_pvt;
1400 	struct xen_netif_tx_response *resp;
1401 
1402 	resp = RING_GET_RESPONSE(&queue->tx, i);
1403 	resp->id     = txp->id;
1404 	resp->status = st;
1405 
1406 	while (extra_count-- != 0)
1407 		RING_GET_RESPONSE(&queue->tx, ++i)->status = XEN_NETIF_RSP_NULL;
1408 
1409 	queue->tx.rsp_prod_pvt = ++i;
1410 }
1411 
1412 static void push_tx_responses(struct xenvif_queue *queue)
1413 {
1414 	int notify;
1415 
1416 	RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->tx, notify);
1417 	if (notify)
1418 		notify_remote_via_irq(queue->tx_irq);
1419 }
1420 
1421 void xenvif_idx_unmap(struct xenvif_queue *queue, u16 pending_idx)
1422 {
1423 	int ret;
1424 	struct gnttab_unmap_grant_ref tx_unmap_op;
1425 
1426 	gnttab_set_unmap_op(&tx_unmap_op,
1427 			    idx_to_kaddr(queue, pending_idx),
1428 			    GNTMAP_host_map,
1429 			    queue->grant_tx_handle[pending_idx]);
1430 	xenvif_grant_handle_reset(queue, pending_idx);
1431 
1432 	ret = gnttab_unmap_refs(&tx_unmap_op, NULL,
1433 				&queue->mmap_pages[pending_idx], 1);
1434 	if (ret) {
1435 		netdev_err(queue->vif->dev,
1436 			   "Unmap fail: ret: %d pending_idx: %d host_addr: %llx handle: 0x%x status: %d\n",
1437 			   ret,
1438 			   pending_idx,
1439 			   tx_unmap_op.host_addr,
1440 			   tx_unmap_op.handle,
1441 			   tx_unmap_op.status);
1442 		BUG();
1443 	}
1444 }
1445 
1446 static inline int tx_work_todo(struct xenvif_queue *queue)
1447 {
1448 	if (likely(RING_HAS_UNCONSUMED_REQUESTS(&queue->tx)))
1449 		return 1;
1450 
1451 	return 0;
1452 }
1453 
1454 static inline bool tx_dealloc_work_todo(struct xenvif_queue *queue)
1455 {
1456 	return queue->dealloc_cons != queue->dealloc_prod;
1457 }
1458 
1459 void xenvif_unmap_frontend_data_rings(struct xenvif_queue *queue)
1460 {
1461 	if (queue->tx.sring)
1462 		xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(queue->vif),
1463 					queue->tx.sring);
1464 	if (queue->rx.sring)
1465 		xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(queue->vif),
1466 					queue->rx.sring);
1467 }
1468 
1469 int xenvif_map_frontend_data_rings(struct xenvif_queue *queue,
1470 				   grant_ref_t tx_ring_ref,
1471 				   grant_ref_t rx_ring_ref)
1472 {
1473 	void *addr;
1474 	struct xen_netif_tx_sring *txs;
1475 	struct xen_netif_rx_sring *rxs;
1476 	RING_IDX rsp_prod, req_prod;
1477 	int err;
1478 
1479 	err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(queue->vif),
1480 				     &tx_ring_ref, 1, &addr);
1481 	if (err)
1482 		goto err;
1483 
1484 	txs = (struct xen_netif_tx_sring *)addr;
1485 	rsp_prod = READ_ONCE(txs->rsp_prod);
1486 	req_prod = READ_ONCE(txs->req_prod);
1487 
1488 	BACK_RING_ATTACH(&queue->tx, txs, rsp_prod, XEN_PAGE_SIZE);
1489 
1490 	err = -EIO;
1491 	if (req_prod - rsp_prod > RING_SIZE(&queue->tx))
1492 		goto err;
1493 
1494 	err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(queue->vif),
1495 				     &rx_ring_ref, 1, &addr);
1496 	if (err)
1497 		goto err;
1498 
1499 	rxs = (struct xen_netif_rx_sring *)addr;
1500 	rsp_prod = READ_ONCE(rxs->rsp_prod);
1501 	req_prod = READ_ONCE(rxs->req_prod);
1502 
1503 	BACK_RING_ATTACH(&queue->rx, rxs, rsp_prod, XEN_PAGE_SIZE);
1504 
1505 	err = -EIO;
1506 	if (req_prod - rsp_prod > RING_SIZE(&queue->rx))
1507 		goto err;
1508 
1509 	return 0;
1510 
1511 err:
1512 	xenvif_unmap_frontend_data_rings(queue);
1513 	return err;
1514 }
1515 
1516 static bool xenvif_dealloc_kthread_should_stop(struct xenvif_queue *queue)
1517 {
1518 	/* Dealloc thread must remain running until all inflight
1519 	 * packets complete.
1520 	 */
1521 	return kthread_should_stop() &&
1522 		!atomic_read(&queue->inflight_packets);
1523 }
1524 
1525 int xenvif_dealloc_kthread(void *data)
1526 {
1527 	struct xenvif_queue *queue = data;
1528 
1529 	for (;;) {
1530 		wait_event_interruptible(queue->dealloc_wq,
1531 					 tx_dealloc_work_todo(queue) ||
1532 					 xenvif_dealloc_kthread_should_stop(queue));
1533 		if (xenvif_dealloc_kthread_should_stop(queue))
1534 			break;
1535 
1536 		xenvif_tx_dealloc_action(queue);
1537 		cond_resched();
1538 	}
1539 
1540 	/* Unmap anything remaining*/
1541 	if (tx_dealloc_work_todo(queue))
1542 		xenvif_tx_dealloc_action(queue);
1543 
1544 	return 0;
1545 }
1546 
1547 static void make_ctrl_response(struct xenvif *vif,
1548 			       const struct xen_netif_ctrl_request *req,
1549 			       u32 status, u32 data)
1550 {
1551 	RING_IDX idx = vif->ctrl.rsp_prod_pvt;
1552 	struct xen_netif_ctrl_response rsp = {
1553 		.id = req->id,
1554 		.type = req->type,
1555 		.status = status,
1556 		.data = data,
1557 	};
1558 
1559 	*RING_GET_RESPONSE(&vif->ctrl, idx) = rsp;
1560 	vif->ctrl.rsp_prod_pvt = ++idx;
1561 }
1562 
1563 static void push_ctrl_response(struct xenvif *vif)
1564 {
1565 	int notify;
1566 
1567 	RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&vif->ctrl, notify);
1568 	if (notify)
1569 		notify_remote_via_irq(vif->ctrl_irq);
1570 }
1571 
1572 static void process_ctrl_request(struct xenvif *vif,
1573 				 const struct xen_netif_ctrl_request *req)
1574 {
1575 	u32 status = XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED;
1576 	u32 data = 0;
1577 
1578 	switch (req->type) {
1579 	case XEN_NETIF_CTRL_TYPE_SET_HASH_ALGORITHM:
1580 		status = xenvif_set_hash_alg(vif, req->data[0]);
1581 		break;
1582 
1583 	case XEN_NETIF_CTRL_TYPE_GET_HASH_FLAGS:
1584 		status = xenvif_get_hash_flags(vif, &data);
1585 		break;
1586 
1587 	case XEN_NETIF_CTRL_TYPE_SET_HASH_FLAGS:
1588 		status = xenvif_set_hash_flags(vif, req->data[0]);
1589 		break;
1590 
1591 	case XEN_NETIF_CTRL_TYPE_SET_HASH_KEY:
1592 		status = xenvif_set_hash_key(vif, req->data[0],
1593 					     req->data[1]);
1594 		break;
1595 
1596 	case XEN_NETIF_CTRL_TYPE_GET_HASH_MAPPING_SIZE:
1597 		status = XEN_NETIF_CTRL_STATUS_SUCCESS;
1598 		data = XEN_NETBK_MAX_HASH_MAPPING_SIZE;
1599 		break;
1600 
1601 	case XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING_SIZE:
1602 		status = xenvif_set_hash_mapping_size(vif,
1603 						      req->data[0]);
1604 		break;
1605 
1606 	case XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING:
1607 		status = xenvif_set_hash_mapping(vif, req->data[0],
1608 						 req->data[1],
1609 						 req->data[2]);
1610 		break;
1611 
1612 	default:
1613 		break;
1614 	}
1615 
1616 	make_ctrl_response(vif, req, status, data);
1617 	push_ctrl_response(vif);
1618 }
1619 
1620 static void xenvif_ctrl_action(struct xenvif *vif)
1621 {
1622 	for (;;) {
1623 		RING_IDX req_prod, req_cons;
1624 
1625 		req_prod = vif->ctrl.sring->req_prod;
1626 		req_cons = vif->ctrl.req_cons;
1627 
1628 		/* Make sure we can see requests before we process them. */
1629 		rmb();
1630 
1631 		if (req_cons == req_prod)
1632 			break;
1633 
1634 		while (req_cons != req_prod) {
1635 			struct xen_netif_ctrl_request req;
1636 
1637 			RING_COPY_REQUEST(&vif->ctrl, req_cons, &req);
1638 			req_cons++;
1639 
1640 			process_ctrl_request(vif, &req);
1641 		}
1642 
1643 		vif->ctrl.req_cons = req_cons;
1644 		vif->ctrl.sring->req_event = req_cons + 1;
1645 	}
1646 }
1647 
1648 static bool xenvif_ctrl_work_todo(struct xenvif *vif)
1649 {
1650 	if (likely(RING_HAS_UNCONSUMED_REQUESTS(&vif->ctrl)))
1651 		return true;
1652 
1653 	return false;
1654 }
1655 
1656 irqreturn_t xenvif_ctrl_irq_fn(int irq, void *data)
1657 {
1658 	struct xenvif *vif = data;
1659 	unsigned int eoi_flag = XEN_EOI_FLAG_SPURIOUS;
1660 
1661 	while (xenvif_ctrl_work_todo(vif)) {
1662 		xenvif_ctrl_action(vif);
1663 		eoi_flag = 0;
1664 	}
1665 
1666 	xen_irq_lateeoi(irq, eoi_flag);
1667 
1668 	return IRQ_HANDLED;
1669 }
1670 
1671 static int __init netback_init(void)
1672 {
1673 	int rc = 0;
1674 
1675 	if (!xen_domain())
1676 		return -ENODEV;
1677 
1678 	/* Allow as many queues as there are CPUs but max. 8 if user has not
1679 	 * specified a value.
1680 	 */
1681 	if (xenvif_max_queues == 0)
1682 		xenvif_max_queues = min_t(unsigned int, MAX_QUEUES_DEFAULT,
1683 					  num_online_cpus());
1684 
1685 	if (fatal_skb_slots < XEN_NETBK_LEGACY_SLOTS_MAX) {
1686 		pr_info("fatal_skb_slots too small (%d), bump it to XEN_NETBK_LEGACY_SLOTS_MAX (%d)\n",
1687 			fatal_skb_slots, XEN_NETBK_LEGACY_SLOTS_MAX);
1688 		fatal_skb_slots = XEN_NETBK_LEGACY_SLOTS_MAX;
1689 	}
1690 
1691 	rc = xenvif_xenbus_init();
1692 	if (rc)
1693 		goto failed_init;
1694 
1695 #ifdef CONFIG_DEBUG_FS
1696 	xen_netback_dbg_root = debugfs_create_dir("xen-netback", NULL);
1697 #endif /* CONFIG_DEBUG_FS */
1698 
1699 	return 0;
1700 
1701 failed_init:
1702 	return rc;
1703 }
1704 
1705 module_init(netback_init);
1706 
1707 static void __exit netback_fini(void)
1708 {
1709 #ifdef CONFIG_DEBUG_FS
1710 	debugfs_remove_recursive(xen_netback_dbg_root);
1711 #endif /* CONFIG_DEBUG_FS */
1712 	xenvif_xenbus_fini();
1713 }
1714 module_exit(netback_fini);
1715 
1716 MODULE_LICENSE("Dual BSD/GPL");
1717 MODULE_ALIAS("xen-backend:vif");
1718