1 // SPDX-License-Identifier: (GPL-2.0 OR MIT)
2 /* Google virtual Ethernet (gve) driver
3  *
4  * Copyright (C) 2015-2021 Google, Inc.
5  */
6 
7 #include "gve.h"
8 #include "gve_adminq.h"
9 #include "gve_utils.h"
10 #include <linux/ip.h>
11 #include <linux/tcp.h>
12 #include <linux/vmalloc.h>
13 #include <linux/skbuff.h>
14 #include <net/xdp_sock_drv.h>
15 
gve_tx_put_doorbell(struct gve_priv * priv,struct gve_queue_resources * q_resources,u32 val)16 static inline void gve_tx_put_doorbell(struct gve_priv *priv,
17 				       struct gve_queue_resources *q_resources,
18 				       u32 val)
19 {
20 	iowrite32be(val, &priv->db_bar2[be32_to_cpu(q_resources->db_index)]);
21 }
22 
gve_xdp_tx_flush(struct gve_priv * priv,u32 xdp_qid)23 void gve_xdp_tx_flush(struct gve_priv *priv, u32 xdp_qid)
24 {
25 	u32 tx_qid = gve_xdp_tx_queue_id(priv, xdp_qid);
26 	struct gve_tx_ring *tx = &priv->tx[tx_qid];
27 
28 	gve_tx_put_doorbell(priv, tx->q_resources, tx->req);
29 }
30 
31 /* gvnic can only transmit from a Registered Segment.
32  * We copy skb payloads into the registered segment before writing Tx
33  * descriptors and ringing the Tx doorbell.
34  *
35  * gve_tx_fifo_* manages the Registered Segment as a FIFO - clients must
36  * free allocations in the order they were allocated.
37  */
38 
gve_tx_fifo_init(struct gve_priv * priv,struct gve_tx_fifo * fifo)39 static int gve_tx_fifo_init(struct gve_priv *priv, struct gve_tx_fifo *fifo)
40 {
41 	fifo->base = vmap(fifo->qpl->pages, fifo->qpl->num_entries, VM_MAP,
42 			  PAGE_KERNEL);
43 	if (unlikely(!fifo->base)) {
44 		netif_err(priv, drv, priv->dev, "Failed to vmap fifo, qpl_id = %d\n",
45 			  fifo->qpl->id);
46 		return -ENOMEM;
47 	}
48 
49 	fifo->size = fifo->qpl->num_entries * PAGE_SIZE;
50 	atomic_set(&fifo->available, fifo->size);
51 	fifo->head = 0;
52 	return 0;
53 }
54 
gve_tx_fifo_release(struct gve_priv * priv,struct gve_tx_fifo * fifo)55 static void gve_tx_fifo_release(struct gve_priv *priv, struct gve_tx_fifo *fifo)
56 {
57 	WARN(atomic_read(&fifo->available) != fifo->size,
58 	     "Releasing non-empty fifo");
59 
60 	vunmap(fifo->base);
61 }
62 
gve_tx_fifo_pad_alloc_one_frag(struct gve_tx_fifo * fifo,size_t bytes)63 static int gve_tx_fifo_pad_alloc_one_frag(struct gve_tx_fifo *fifo,
64 					  size_t bytes)
65 {
66 	return (fifo->head + bytes < fifo->size) ? 0 : fifo->size - fifo->head;
67 }
68 
gve_tx_fifo_can_alloc(struct gve_tx_fifo * fifo,size_t bytes)69 static bool gve_tx_fifo_can_alloc(struct gve_tx_fifo *fifo, size_t bytes)
70 {
71 	return (atomic_read(&fifo->available) <= bytes) ? false : true;
72 }
73 
74 /* gve_tx_alloc_fifo - Allocate fragment(s) from Tx FIFO
75  * @fifo: FIFO to allocate from
76  * @bytes: Allocation size
77  * @iov: Scatter-gather elements to fill with allocation fragment base/len
78  *
79  * Returns number of valid elements in iov[] or negative on error.
80  *
81  * Allocations from a given FIFO must be externally synchronized but concurrent
82  * allocation and frees are allowed.
83  */
gve_tx_alloc_fifo(struct gve_tx_fifo * fifo,size_t bytes,struct gve_tx_iovec iov[2])84 static int gve_tx_alloc_fifo(struct gve_tx_fifo *fifo, size_t bytes,
85 			     struct gve_tx_iovec iov[2])
86 {
87 	size_t overflow, padding;
88 	u32 aligned_head;
89 	int nfrags = 0;
90 
91 	if (!bytes)
92 		return 0;
93 
94 	/* This check happens before we know how much padding is needed to
95 	 * align to a cacheline boundary for the payload, but that is fine,
96 	 * because the FIFO head always start aligned, and the FIFO's boundaries
97 	 * are aligned, so if there is space for the data, there is space for
98 	 * the padding to the next alignment.
99 	 */
100 	WARN(!gve_tx_fifo_can_alloc(fifo, bytes),
101 	     "Reached %s when there's not enough space in the fifo", __func__);
102 
103 	nfrags++;
104 
105 	iov[0].iov_offset = fifo->head;
106 	iov[0].iov_len = bytes;
107 	fifo->head += bytes;
108 
109 	if (fifo->head > fifo->size) {
110 		/* If the allocation did not fit in the tail fragment of the
111 		 * FIFO, also use the head fragment.
112 		 */
113 		nfrags++;
114 		overflow = fifo->head - fifo->size;
115 		iov[0].iov_len -= overflow;
116 		iov[1].iov_offset = 0;	/* Start of fifo*/
117 		iov[1].iov_len = overflow;
118 
119 		fifo->head = overflow;
120 	}
121 
122 	/* Re-align to a cacheline boundary */
123 	aligned_head = L1_CACHE_ALIGN(fifo->head);
124 	padding = aligned_head - fifo->head;
125 	iov[nfrags - 1].iov_padding = padding;
126 	atomic_sub(bytes + padding, &fifo->available);
127 	fifo->head = aligned_head;
128 
129 	if (fifo->head == fifo->size)
130 		fifo->head = 0;
131 
132 	return nfrags;
133 }
134 
135 /* gve_tx_free_fifo - Return space to Tx FIFO
136  * @fifo: FIFO to return fragments to
137  * @bytes: Bytes to free
138  */
gve_tx_free_fifo(struct gve_tx_fifo * fifo,size_t bytes)139 static void gve_tx_free_fifo(struct gve_tx_fifo *fifo, size_t bytes)
140 {
141 	atomic_add(bytes, &fifo->available);
142 }
143 
gve_tx_clear_buffer_state(struct gve_tx_buffer_state * info)144 static size_t gve_tx_clear_buffer_state(struct gve_tx_buffer_state *info)
145 {
146 	size_t space_freed = 0;
147 	int i;
148 
149 	for (i = 0; i < ARRAY_SIZE(info->iov); i++) {
150 		space_freed += info->iov[i].iov_len + info->iov[i].iov_padding;
151 		info->iov[i].iov_len = 0;
152 		info->iov[i].iov_padding = 0;
153 	}
154 	return space_freed;
155 }
156 
gve_clean_xdp_done(struct gve_priv * priv,struct gve_tx_ring * tx,u32 to_do)157 static int gve_clean_xdp_done(struct gve_priv *priv, struct gve_tx_ring *tx,
158 			      u32 to_do)
159 {
160 	struct gve_tx_buffer_state *info;
161 	u32 clean_end = tx->done + to_do;
162 	u64 pkts = 0, bytes = 0;
163 	size_t space_freed = 0;
164 	u32 xsk_complete = 0;
165 	u32 idx;
166 
167 	for (; tx->done < clean_end; tx->done++) {
168 		idx = tx->done & tx->mask;
169 		info = &tx->info[idx];
170 
171 		if (unlikely(!info->xdp.size))
172 			continue;
173 
174 		bytes += info->xdp.size;
175 		pkts++;
176 		xsk_complete += info->xdp.is_xsk;
177 
178 		info->xdp.size = 0;
179 		if (info->xdp_frame) {
180 			xdp_return_frame(info->xdp_frame);
181 			info->xdp_frame = NULL;
182 		}
183 		space_freed += gve_tx_clear_buffer_state(info);
184 	}
185 
186 	gve_tx_free_fifo(&tx->tx_fifo, space_freed);
187 	if (xsk_complete > 0 && tx->xsk_pool)
188 		xsk_tx_completed(tx->xsk_pool, xsk_complete);
189 	u64_stats_update_begin(&tx->statss);
190 	tx->bytes_done += bytes;
191 	tx->pkt_done += pkts;
192 	u64_stats_update_end(&tx->statss);
193 	return pkts;
194 }
195 
196 static int gve_clean_tx_done(struct gve_priv *priv, struct gve_tx_ring *tx,
197 			     u32 to_do, bool try_to_wake);
198 
gve_tx_free_ring(struct gve_priv * priv,int idx)199 static void gve_tx_free_ring(struct gve_priv *priv, int idx)
200 {
201 	struct gve_tx_ring *tx = &priv->tx[idx];
202 	struct device *hdev = &priv->pdev->dev;
203 	size_t bytes;
204 	u32 slots;
205 
206 	gve_tx_remove_from_block(priv, idx);
207 	slots = tx->mask + 1;
208 	if (tx->q_num < priv->tx_cfg.num_queues) {
209 		gve_clean_tx_done(priv, tx, priv->tx_desc_cnt, false);
210 		netdev_tx_reset_queue(tx->netdev_txq);
211 	} else {
212 		gve_clean_xdp_done(priv, tx, priv->tx_desc_cnt);
213 	}
214 
215 	dma_free_coherent(hdev, sizeof(*tx->q_resources),
216 			  tx->q_resources, tx->q_resources_bus);
217 	tx->q_resources = NULL;
218 
219 	if (!tx->raw_addressing) {
220 		gve_tx_fifo_release(priv, &tx->tx_fifo);
221 		gve_unassign_qpl(priv, tx->tx_fifo.qpl->id);
222 		tx->tx_fifo.qpl = NULL;
223 	}
224 
225 	bytes = sizeof(*tx->desc) * slots;
226 	dma_free_coherent(hdev, bytes, tx->desc, tx->bus);
227 	tx->desc = NULL;
228 
229 	vfree(tx->info);
230 	tx->info = NULL;
231 
232 	netif_dbg(priv, drv, priv->dev, "freed tx queue %d\n", idx);
233 }
234 
gve_tx_alloc_ring(struct gve_priv * priv,int idx)235 static int gve_tx_alloc_ring(struct gve_priv *priv, int idx)
236 {
237 	struct gve_tx_ring *tx = &priv->tx[idx];
238 	struct device *hdev = &priv->pdev->dev;
239 	u32 slots = priv->tx_desc_cnt;
240 	size_t bytes;
241 
242 	/* Make sure everything is zeroed to start */
243 	memset(tx, 0, sizeof(*tx));
244 	spin_lock_init(&tx->clean_lock);
245 	spin_lock_init(&tx->xdp_lock);
246 	tx->q_num = idx;
247 
248 	tx->mask = slots - 1;
249 
250 	/* alloc metadata */
251 	tx->info = vcalloc(slots, sizeof(*tx->info));
252 	if (!tx->info)
253 		return -ENOMEM;
254 
255 	/* alloc tx queue */
256 	bytes = sizeof(*tx->desc) * slots;
257 	tx->desc = dma_alloc_coherent(hdev, bytes, &tx->bus, GFP_KERNEL);
258 	if (!tx->desc)
259 		goto abort_with_info;
260 
261 	tx->raw_addressing = priv->queue_format == GVE_GQI_RDA_FORMAT;
262 	tx->dev = &priv->pdev->dev;
263 	if (!tx->raw_addressing) {
264 		tx->tx_fifo.qpl = gve_assign_tx_qpl(priv, idx);
265 		if (!tx->tx_fifo.qpl)
266 			goto abort_with_desc;
267 		/* map Tx FIFO */
268 		if (gve_tx_fifo_init(priv, &tx->tx_fifo))
269 			goto abort_with_qpl;
270 	}
271 
272 	tx->q_resources =
273 		dma_alloc_coherent(hdev,
274 				   sizeof(*tx->q_resources),
275 				   &tx->q_resources_bus,
276 				   GFP_KERNEL);
277 	if (!tx->q_resources)
278 		goto abort_with_fifo;
279 
280 	netif_dbg(priv, drv, priv->dev, "tx[%d]->bus=%lx\n", idx,
281 		  (unsigned long)tx->bus);
282 	if (idx < priv->tx_cfg.num_queues)
283 		tx->netdev_txq = netdev_get_tx_queue(priv->dev, idx);
284 	gve_tx_add_to_block(priv, idx);
285 
286 	return 0;
287 
288 abort_with_fifo:
289 	if (!tx->raw_addressing)
290 		gve_tx_fifo_release(priv, &tx->tx_fifo);
291 abort_with_qpl:
292 	if (!tx->raw_addressing)
293 		gve_unassign_qpl(priv, tx->tx_fifo.qpl->id);
294 abort_with_desc:
295 	dma_free_coherent(hdev, bytes, tx->desc, tx->bus);
296 	tx->desc = NULL;
297 abort_with_info:
298 	vfree(tx->info);
299 	tx->info = NULL;
300 	return -ENOMEM;
301 }
302 
gve_tx_alloc_rings(struct gve_priv * priv,int start_id,int num_rings)303 int gve_tx_alloc_rings(struct gve_priv *priv, int start_id, int num_rings)
304 {
305 	int err = 0;
306 	int i;
307 
308 	for (i = start_id; i < start_id + num_rings; i++) {
309 		err = gve_tx_alloc_ring(priv, i);
310 		if (err) {
311 			netif_err(priv, drv, priv->dev,
312 				  "Failed to alloc tx ring=%d: err=%d\n",
313 				  i, err);
314 			break;
315 		}
316 	}
317 	/* Unallocate if there was an error */
318 	if (err) {
319 		int j;
320 
321 		for (j = start_id; j < i; j++)
322 			gve_tx_free_ring(priv, j);
323 	}
324 	return err;
325 }
326 
gve_tx_free_rings_gqi(struct gve_priv * priv,int start_id,int num_rings)327 void gve_tx_free_rings_gqi(struct gve_priv *priv, int start_id, int num_rings)
328 {
329 	int i;
330 
331 	for (i = start_id; i < start_id + num_rings; i++)
332 		gve_tx_free_ring(priv, i);
333 }
334 
335 /* gve_tx_avail - Calculates the number of slots available in the ring
336  * @tx: tx ring to check
337  *
338  * Returns the number of slots available
339  *
340  * The capacity of the queue is mask + 1. We don't need to reserve an entry.
341  **/
gve_tx_avail(struct gve_tx_ring * tx)342 static inline u32 gve_tx_avail(struct gve_tx_ring *tx)
343 {
344 	return tx->mask + 1 - (tx->req - tx->done);
345 }
346 
gve_skb_fifo_bytes_required(struct gve_tx_ring * tx,struct sk_buff * skb)347 static inline int gve_skb_fifo_bytes_required(struct gve_tx_ring *tx,
348 					      struct sk_buff *skb)
349 {
350 	int pad_bytes, align_hdr_pad;
351 	int bytes;
352 	int hlen;
353 
354 	hlen = skb_is_gso(skb) ? skb_checksum_start_offset(skb) + tcp_hdrlen(skb) :
355 				 min_t(int, GVE_GQ_TX_MIN_PKT_DESC_BYTES, skb->len);
356 
357 	pad_bytes = gve_tx_fifo_pad_alloc_one_frag(&tx->tx_fifo,
358 						   hlen);
359 	/* We need to take into account the header alignment padding. */
360 	align_hdr_pad = L1_CACHE_ALIGN(hlen) - hlen;
361 	bytes = align_hdr_pad + pad_bytes + skb->len;
362 
363 	return bytes;
364 }
365 
366 /* The most descriptors we could need is MAX_SKB_FRAGS + 4 :
367  * 1 for each skb frag
368  * 1 for the skb linear portion
369  * 1 for when tcp hdr needs to be in separate descriptor
370  * 1 if the payload wraps to the beginning of the FIFO
371  * 1 for metadata descriptor
372  */
373 #define MAX_TX_DESC_NEEDED	(MAX_SKB_FRAGS + 4)
gve_tx_unmap_buf(struct device * dev,struct gve_tx_buffer_state * info)374 static void gve_tx_unmap_buf(struct device *dev, struct gve_tx_buffer_state *info)
375 {
376 	if (info->skb) {
377 		dma_unmap_single(dev, dma_unmap_addr(info, dma),
378 				 dma_unmap_len(info, len),
379 				 DMA_TO_DEVICE);
380 		dma_unmap_len_set(info, len, 0);
381 	} else {
382 		dma_unmap_page(dev, dma_unmap_addr(info, dma),
383 			       dma_unmap_len(info, len),
384 			       DMA_TO_DEVICE);
385 		dma_unmap_len_set(info, len, 0);
386 	}
387 }
388 
389 /* Check if sufficient resources (descriptor ring space, FIFO space) are
390  * available to transmit the given number of bytes.
391  */
gve_can_tx(struct gve_tx_ring * tx,int bytes_required)392 static inline bool gve_can_tx(struct gve_tx_ring *tx, int bytes_required)
393 {
394 	bool can_alloc = true;
395 
396 	if (!tx->raw_addressing)
397 		can_alloc = gve_tx_fifo_can_alloc(&tx->tx_fifo, bytes_required);
398 
399 	return (gve_tx_avail(tx) >= MAX_TX_DESC_NEEDED && can_alloc);
400 }
401 
402 static_assert(NAPI_POLL_WEIGHT >= MAX_TX_DESC_NEEDED);
403 
404 /* Stops the queue if the skb cannot be transmitted. */
gve_maybe_stop_tx(struct gve_priv * priv,struct gve_tx_ring * tx,struct sk_buff * skb)405 static int gve_maybe_stop_tx(struct gve_priv *priv, struct gve_tx_ring *tx,
406 			     struct sk_buff *skb)
407 {
408 	int bytes_required = 0;
409 	u32 nic_done;
410 	u32 to_do;
411 	int ret;
412 
413 	if (!tx->raw_addressing)
414 		bytes_required = gve_skb_fifo_bytes_required(tx, skb);
415 
416 	if (likely(gve_can_tx(tx, bytes_required)))
417 		return 0;
418 
419 	ret = -EBUSY;
420 	spin_lock(&tx->clean_lock);
421 	nic_done = gve_tx_load_event_counter(priv, tx);
422 	to_do = nic_done - tx->done;
423 
424 	/* Only try to clean if there is hope for TX */
425 	if (to_do + gve_tx_avail(tx) >= MAX_TX_DESC_NEEDED) {
426 		if (to_do > 0) {
427 			to_do = min_t(u32, to_do, NAPI_POLL_WEIGHT);
428 			gve_clean_tx_done(priv, tx, to_do, false);
429 		}
430 		if (likely(gve_can_tx(tx, bytes_required)))
431 			ret = 0;
432 	}
433 	if (ret) {
434 		/* No space, so stop the queue */
435 		tx->stop_queue++;
436 		netif_tx_stop_queue(tx->netdev_txq);
437 	}
438 	spin_unlock(&tx->clean_lock);
439 
440 	return ret;
441 }
442 
gve_tx_fill_pkt_desc(union gve_tx_desc * pkt_desc,u16 csum_offset,u8 ip_summed,bool is_gso,int l4_hdr_offset,u32 desc_cnt,u16 hlen,u64 addr,u16 pkt_len)443 static void gve_tx_fill_pkt_desc(union gve_tx_desc *pkt_desc,
444 				 u16 csum_offset, u8 ip_summed, bool is_gso,
445 				 int l4_hdr_offset, u32 desc_cnt,
446 				 u16 hlen, u64 addr, u16 pkt_len)
447 {
448 	/* l4_hdr_offset and csum_offset are in units of 16-bit words */
449 	if (is_gso) {
450 		pkt_desc->pkt.type_flags = GVE_TXD_TSO | GVE_TXF_L4CSUM;
451 		pkt_desc->pkt.l4_csum_offset = csum_offset >> 1;
452 		pkt_desc->pkt.l4_hdr_offset = l4_hdr_offset >> 1;
453 	} else if (likely(ip_summed == CHECKSUM_PARTIAL)) {
454 		pkt_desc->pkt.type_flags = GVE_TXD_STD | GVE_TXF_L4CSUM;
455 		pkt_desc->pkt.l4_csum_offset = csum_offset >> 1;
456 		pkt_desc->pkt.l4_hdr_offset = l4_hdr_offset >> 1;
457 	} else {
458 		pkt_desc->pkt.type_flags = GVE_TXD_STD;
459 		pkt_desc->pkt.l4_csum_offset = 0;
460 		pkt_desc->pkt.l4_hdr_offset = 0;
461 	}
462 	pkt_desc->pkt.desc_cnt = desc_cnt;
463 	pkt_desc->pkt.len = cpu_to_be16(pkt_len);
464 	pkt_desc->pkt.seg_len = cpu_to_be16(hlen);
465 	pkt_desc->pkt.seg_addr = cpu_to_be64(addr);
466 }
467 
gve_tx_fill_mtd_desc(union gve_tx_desc * mtd_desc,struct sk_buff * skb)468 static void gve_tx_fill_mtd_desc(union gve_tx_desc *mtd_desc,
469 				 struct sk_buff *skb)
470 {
471 	BUILD_BUG_ON(sizeof(mtd_desc->mtd) != sizeof(mtd_desc->pkt));
472 
473 	mtd_desc->mtd.type_flags = GVE_TXD_MTD | GVE_MTD_SUBTYPE_PATH;
474 	mtd_desc->mtd.path_state = GVE_MTD_PATH_STATE_DEFAULT |
475 				   GVE_MTD_PATH_HASH_L4;
476 	mtd_desc->mtd.path_hash = cpu_to_be32(skb->hash);
477 	mtd_desc->mtd.reserved0 = 0;
478 	mtd_desc->mtd.reserved1 = 0;
479 }
480 
gve_tx_fill_seg_desc(union gve_tx_desc * seg_desc,u16 l3_offset,u16 gso_size,bool is_gso_v6,bool is_gso,u16 len,u64 addr)481 static void gve_tx_fill_seg_desc(union gve_tx_desc *seg_desc,
482 				 u16 l3_offset, u16 gso_size,
483 				 bool is_gso_v6, bool is_gso,
484 				 u16 len, u64 addr)
485 {
486 	seg_desc->seg.type_flags = GVE_TXD_SEG;
487 	if (is_gso) {
488 		if (is_gso_v6)
489 			seg_desc->seg.type_flags |= GVE_TXSF_IPV6;
490 		seg_desc->seg.l3_offset = l3_offset >> 1;
491 		seg_desc->seg.mss = cpu_to_be16(gso_size);
492 	}
493 	seg_desc->seg.seg_len = cpu_to_be16(len);
494 	seg_desc->seg.seg_addr = cpu_to_be64(addr);
495 }
496 
gve_dma_sync_for_device(struct device * dev,dma_addr_t * page_buses,u64 iov_offset,u64 iov_len)497 static void gve_dma_sync_for_device(struct device *dev, dma_addr_t *page_buses,
498 				    u64 iov_offset, u64 iov_len)
499 {
500 	u64 last_page = (iov_offset + iov_len - 1) / PAGE_SIZE;
501 	u64 first_page = iov_offset / PAGE_SIZE;
502 	u64 page;
503 
504 	for (page = first_page; page <= last_page; page++)
505 		dma_sync_single_for_device(dev, page_buses[page], PAGE_SIZE, DMA_TO_DEVICE);
506 }
507 
gve_tx_add_skb_copy(struct gve_priv * priv,struct gve_tx_ring * tx,struct sk_buff * skb)508 static int gve_tx_add_skb_copy(struct gve_priv *priv, struct gve_tx_ring *tx, struct sk_buff *skb)
509 {
510 	int pad_bytes, hlen, hdr_nfrags, payload_nfrags, l4_hdr_offset;
511 	union gve_tx_desc *pkt_desc, *seg_desc;
512 	struct gve_tx_buffer_state *info;
513 	int mtd_desc_nr = !!skb->l4_hash;
514 	bool is_gso = skb_is_gso(skb);
515 	u32 idx = tx->req & tx->mask;
516 	int payload_iov = 2;
517 	int copy_offset;
518 	u32 next_idx;
519 	int i;
520 
521 	info = &tx->info[idx];
522 	pkt_desc = &tx->desc[idx];
523 
524 	l4_hdr_offset = skb_checksum_start_offset(skb);
525 	/* If the skb is gso, then we want the tcp header alone in the first segment
526 	 * otherwise we want the minimum required by the gVNIC spec.
527 	 */
528 	hlen = is_gso ? l4_hdr_offset + tcp_hdrlen(skb) :
529 			min_t(int, GVE_GQ_TX_MIN_PKT_DESC_BYTES, skb->len);
530 
531 	info->skb =  skb;
532 	/* We don't want to split the header, so if necessary, pad to the end
533 	 * of the fifo and then put the header at the beginning of the fifo.
534 	 */
535 	pad_bytes = gve_tx_fifo_pad_alloc_one_frag(&tx->tx_fifo, hlen);
536 	hdr_nfrags = gve_tx_alloc_fifo(&tx->tx_fifo, hlen + pad_bytes,
537 				       &info->iov[0]);
538 	WARN(!hdr_nfrags, "hdr_nfrags should never be 0!");
539 	payload_nfrags = gve_tx_alloc_fifo(&tx->tx_fifo, skb->len - hlen,
540 					   &info->iov[payload_iov]);
541 
542 	gve_tx_fill_pkt_desc(pkt_desc, skb->csum_offset, skb->ip_summed,
543 			     is_gso, l4_hdr_offset,
544 			     1 + mtd_desc_nr + payload_nfrags, hlen,
545 			     info->iov[hdr_nfrags - 1].iov_offset, skb->len);
546 
547 	skb_copy_bits(skb, 0,
548 		      tx->tx_fifo.base + info->iov[hdr_nfrags - 1].iov_offset,
549 		      hlen);
550 	gve_dma_sync_for_device(&priv->pdev->dev, tx->tx_fifo.qpl->page_buses,
551 				info->iov[hdr_nfrags - 1].iov_offset,
552 				info->iov[hdr_nfrags - 1].iov_len);
553 	copy_offset = hlen;
554 
555 	if (mtd_desc_nr) {
556 		next_idx = (tx->req + 1) & tx->mask;
557 		gve_tx_fill_mtd_desc(&tx->desc[next_idx], skb);
558 	}
559 
560 	for (i = payload_iov; i < payload_nfrags + payload_iov; i++) {
561 		next_idx = (tx->req + 1 + mtd_desc_nr + i - payload_iov) & tx->mask;
562 		seg_desc = &tx->desc[next_idx];
563 
564 		gve_tx_fill_seg_desc(seg_desc, skb_network_offset(skb),
565 				     skb_shinfo(skb)->gso_size,
566 				     skb_is_gso_v6(skb), is_gso,
567 				     info->iov[i].iov_len,
568 				     info->iov[i].iov_offset);
569 
570 		skb_copy_bits(skb, copy_offset,
571 			      tx->tx_fifo.base + info->iov[i].iov_offset,
572 			      info->iov[i].iov_len);
573 		gve_dma_sync_for_device(&priv->pdev->dev, tx->tx_fifo.qpl->page_buses,
574 					info->iov[i].iov_offset,
575 					info->iov[i].iov_len);
576 		copy_offset += info->iov[i].iov_len;
577 	}
578 
579 	return 1 + mtd_desc_nr + payload_nfrags;
580 }
581 
gve_tx_add_skb_no_copy(struct gve_priv * priv,struct gve_tx_ring * tx,struct sk_buff * skb)582 static int gve_tx_add_skb_no_copy(struct gve_priv *priv, struct gve_tx_ring *tx,
583 				  struct sk_buff *skb)
584 {
585 	const struct skb_shared_info *shinfo = skb_shinfo(skb);
586 	int hlen, num_descriptors, l4_hdr_offset;
587 	union gve_tx_desc *pkt_desc, *mtd_desc, *seg_desc;
588 	struct gve_tx_buffer_state *info;
589 	int mtd_desc_nr = !!skb->l4_hash;
590 	bool is_gso = skb_is_gso(skb);
591 	u32 idx = tx->req & tx->mask;
592 	u64 addr;
593 	u32 len;
594 	int i;
595 
596 	info = &tx->info[idx];
597 	pkt_desc = &tx->desc[idx];
598 
599 	l4_hdr_offset = skb_checksum_start_offset(skb);
600 	/* If the skb is gso, then we want only up to the tcp header in the first segment
601 	 * to efficiently replicate on each segment otherwise we want the linear portion
602 	 * of the skb (which will contain the checksum because skb->csum_start and
603 	 * skb->csum_offset are given relative to skb->head) in the first segment.
604 	 */
605 	hlen = is_gso ? l4_hdr_offset + tcp_hdrlen(skb) : skb_headlen(skb);
606 	len = skb_headlen(skb);
607 
608 	info->skb =  skb;
609 
610 	addr = dma_map_single(tx->dev, skb->data, len, DMA_TO_DEVICE);
611 	if (unlikely(dma_mapping_error(tx->dev, addr))) {
612 		tx->dma_mapping_error++;
613 		goto drop;
614 	}
615 	dma_unmap_len_set(info, len, len);
616 	dma_unmap_addr_set(info, dma, addr);
617 
618 	num_descriptors = 1 + shinfo->nr_frags;
619 	if (hlen < len)
620 		num_descriptors++;
621 	if (mtd_desc_nr)
622 		num_descriptors++;
623 
624 	gve_tx_fill_pkt_desc(pkt_desc, skb->csum_offset, skb->ip_summed,
625 			     is_gso, l4_hdr_offset,
626 			     num_descriptors, hlen, addr, skb->len);
627 
628 	if (mtd_desc_nr) {
629 		idx = (idx + 1) & tx->mask;
630 		mtd_desc = &tx->desc[idx];
631 		gve_tx_fill_mtd_desc(mtd_desc, skb);
632 	}
633 
634 	if (hlen < len) {
635 		/* For gso the rest of the linear portion of the skb needs to
636 		 * be in its own descriptor.
637 		 */
638 		len -= hlen;
639 		addr += hlen;
640 		idx = (idx + 1) & tx->mask;
641 		seg_desc = &tx->desc[idx];
642 		gve_tx_fill_seg_desc(seg_desc, skb_network_offset(skb),
643 				     skb_shinfo(skb)->gso_size,
644 				     skb_is_gso_v6(skb), is_gso, len, addr);
645 	}
646 
647 	for (i = 0; i < shinfo->nr_frags; i++) {
648 		const skb_frag_t *frag = &shinfo->frags[i];
649 
650 		idx = (idx + 1) & tx->mask;
651 		seg_desc = &tx->desc[idx];
652 		len = skb_frag_size(frag);
653 		addr = skb_frag_dma_map(tx->dev, frag, 0, len, DMA_TO_DEVICE);
654 		if (unlikely(dma_mapping_error(tx->dev, addr))) {
655 			tx->dma_mapping_error++;
656 			goto unmap_drop;
657 		}
658 		tx->info[idx].skb = NULL;
659 		dma_unmap_len_set(&tx->info[idx], len, len);
660 		dma_unmap_addr_set(&tx->info[idx], dma, addr);
661 
662 		gve_tx_fill_seg_desc(seg_desc, skb_network_offset(skb),
663 				     skb_shinfo(skb)->gso_size,
664 				     skb_is_gso_v6(skb), is_gso, len, addr);
665 	}
666 
667 	return num_descriptors;
668 
669 unmap_drop:
670 	i += num_descriptors - shinfo->nr_frags;
671 	while (i--) {
672 		/* Skip metadata descriptor, if set */
673 		if (i == 1 && mtd_desc_nr == 1)
674 			continue;
675 		idx--;
676 		gve_tx_unmap_buf(tx->dev, &tx->info[idx & tx->mask]);
677 	}
678 drop:
679 	tx->dropped_pkt++;
680 	return 0;
681 }
682 
gve_tx(struct sk_buff * skb,struct net_device * dev)683 netdev_tx_t gve_tx(struct sk_buff *skb, struct net_device *dev)
684 {
685 	struct gve_priv *priv = netdev_priv(dev);
686 	struct gve_tx_ring *tx;
687 	int nsegs;
688 
689 	WARN(skb_get_queue_mapping(skb) >= priv->tx_cfg.num_queues,
690 	     "skb queue index out of range");
691 	tx = &priv->tx[skb_get_queue_mapping(skb)];
692 	if (unlikely(gve_maybe_stop_tx(priv, tx, skb))) {
693 		/* We need to ring the txq doorbell -- we have stopped the Tx
694 		 * queue for want of resources, but prior calls to gve_tx()
695 		 * may have added descriptors without ringing the doorbell.
696 		 */
697 
698 		gve_tx_put_doorbell(priv, tx->q_resources, tx->req);
699 		return NETDEV_TX_BUSY;
700 	}
701 	if (tx->raw_addressing)
702 		nsegs = gve_tx_add_skb_no_copy(priv, tx, skb);
703 	else
704 		nsegs = gve_tx_add_skb_copy(priv, tx, skb);
705 
706 	/* If the packet is getting sent, we need to update the skb */
707 	if (nsegs) {
708 		netdev_tx_sent_queue(tx->netdev_txq, skb->len);
709 		skb_tx_timestamp(skb);
710 		tx->req += nsegs;
711 	} else {
712 		dev_kfree_skb_any(skb);
713 	}
714 
715 	if (!netif_xmit_stopped(tx->netdev_txq) && netdev_xmit_more())
716 		return NETDEV_TX_OK;
717 
718 	/* Give packets to NIC. Even if this packet failed to send the doorbell
719 	 * might need to be rung because of xmit_more.
720 	 */
721 	gve_tx_put_doorbell(priv, tx->q_resources, tx->req);
722 	return NETDEV_TX_OK;
723 }
724 
gve_tx_fill_xdp(struct gve_priv * priv,struct gve_tx_ring * tx,void * data,int len,void * frame_p,bool is_xsk)725 static int gve_tx_fill_xdp(struct gve_priv *priv, struct gve_tx_ring *tx,
726 			   void *data, int len, void *frame_p, bool is_xsk)
727 {
728 	int pad, nfrags, ndescs, iovi, offset;
729 	struct gve_tx_buffer_state *info;
730 	u32 reqi = tx->req;
731 
732 	pad = gve_tx_fifo_pad_alloc_one_frag(&tx->tx_fifo, len);
733 	if (pad >= GVE_GQ_TX_MIN_PKT_DESC_BYTES)
734 		pad = 0;
735 	info = &tx->info[reqi & tx->mask];
736 	info->xdp_frame = frame_p;
737 	info->xdp.size = len;
738 	info->xdp.is_xsk = is_xsk;
739 
740 	nfrags = gve_tx_alloc_fifo(&tx->tx_fifo, pad + len,
741 				   &info->iov[0]);
742 	iovi = pad > 0;
743 	ndescs = nfrags - iovi;
744 	offset = 0;
745 
746 	while (iovi < nfrags) {
747 		if (!offset)
748 			gve_tx_fill_pkt_desc(&tx->desc[reqi & tx->mask], 0,
749 					     CHECKSUM_NONE, false, 0, ndescs,
750 					     info->iov[iovi].iov_len,
751 					     info->iov[iovi].iov_offset, len);
752 		else
753 			gve_tx_fill_seg_desc(&tx->desc[reqi & tx->mask],
754 					     0, 0, false, false,
755 					     info->iov[iovi].iov_len,
756 					     info->iov[iovi].iov_offset);
757 
758 		memcpy(tx->tx_fifo.base + info->iov[iovi].iov_offset,
759 		       data + offset, info->iov[iovi].iov_len);
760 		gve_dma_sync_for_device(&priv->pdev->dev,
761 					tx->tx_fifo.qpl->page_buses,
762 					info->iov[iovi].iov_offset,
763 					info->iov[iovi].iov_len);
764 		offset += info->iov[iovi].iov_len;
765 		iovi++;
766 		reqi++;
767 	}
768 
769 	return ndescs;
770 }
771 
gve_xdp_xmit(struct net_device * dev,int n,struct xdp_frame ** frames,u32 flags)772 int gve_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames,
773 		 u32 flags)
774 {
775 	struct gve_priv *priv = netdev_priv(dev);
776 	struct gve_tx_ring *tx;
777 	int i, err = 0, qid;
778 
779 	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))
780 		return -EINVAL;
781 
782 	qid = gve_xdp_tx_queue_id(priv,
783 				  smp_processor_id() % priv->num_xdp_queues);
784 
785 	tx = &priv->tx[qid];
786 
787 	spin_lock(&tx->xdp_lock);
788 	for (i = 0; i < n; i++) {
789 		err = gve_xdp_xmit_one(priv, tx, frames[i]->data,
790 				       frames[i]->len, frames[i]);
791 		if (err)
792 			break;
793 	}
794 
795 	if (flags & XDP_XMIT_FLUSH)
796 		gve_tx_put_doorbell(priv, tx->q_resources, tx->req);
797 
798 	spin_unlock(&tx->xdp_lock);
799 
800 	u64_stats_update_begin(&tx->statss);
801 	tx->xdp_xmit += n;
802 	tx->xdp_xmit_errors += n - i;
803 	u64_stats_update_end(&tx->statss);
804 
805 	return i ? i : err;
806 }
807 
gve_xdp_xmit_one(struct gve_priv * priv,struct gve_tx_ring * tx,void * data,int len,void * frame_p)808 int gve_xdp_xmit_one(struct gve_priv *priv, struct gve_tx_ring *tx,
809 		     void *data, int len, void *frame_p)
810 {
811 	int nsegs;
812 
813 	if (!gve_can_tx(tx, len + GVE_GQ_TX_MIN_PKT_DESC_BYTES - 1))
814 		return -EBUSY;
815 
816 	nsegs = gve_tx_fill_xdp(priv, tx, data, len, frame_p, false);
817 	tx->req += nsegs;
818 
819 	return 0;
820 }
821 
822 #define GVE_TX_START_THRESH	PAGE_SIZE
823 
gve_clean_tx_done(struct gve_priv * priv,struct gve_tx_ring * tx,u32 to_do,bool try_to_wake)824 static int gve_clean_tx_done(struct gve_priv *priv, struct gve_tx_ring *tx,
825 			     u32 to_do, bool try_to_wake)
826 {
827 	struct gve_tx_buffer_state *info;
828 	u64 pkts = 0, bytes = 0;
829 	size_t space_freed = 0;
830 	struct sk_buff *skb;
831 	u32 idx;
832 	int j;
833 
834 	for (j = 0; j < to_do; j++) {
835 		idx = tx->done & tx->mask;
836 		netif_info(priv, tx_done, priv->dev,
837 			   "[%d] %s: idx=%d (req=%u done=%u)\n",
838 			   tx->q_num, __func__, idx, tx->req, tx->done);
839 		info = &tx->info[idx];
840 		skb = info->skb;
841 
842 		/* Unmap the buffer */
843 		if (tx->raw_addressing)
844 			gve_tx_unmap_buf(tx->dev, info);
845 		tx->done++;
846 		/* Mark as free */
847 		if (skb) {
848 			info->skb = NULL;
849 			bytes += skb->len;
850 			pkts++;
851 			dev_consume_skb_any(skb);
852 			if (tx->raw_addressing)
853 				continue;
854 			space_freed += gve_tx_clear_buffer_state(info);
855 		}
856 	}
857 
858 	if (!tx->raw_addressing)
859 		gve_tx_free_fifo(&tx->tx_fifo, space_freed);
860 	u64_stats_update_begin(&tx->statss);
861 	tx->bytes_done += bytes;
862 	tx->pkt_done += pkts;
863 	u64_stats_update_end(&tx->statss);
864 	netdev_tx_completed_queue(tx->netdev_txq, pkts, bytes);
865 
866 	/* start the queue if we've stopped it */
867 #ifndef CONFIG_BQL
868 	/* Make sure that the doorbells are synced */
869 	smp_mb();
870 #endif
871 	if (try_to_wake && netif_tx_queue_stopped(tx->netdev_txq) &&
872 	    likely(gve_can_tx(tx, GVE_TX_START_THRESH))) {
873 		tx->wake_queue++;
874 		netif_tx_wake_queue(tx->netdev_txq);
875 	}
876 
877 	return pkts;
878 }
879 
gve_tx_load_event_counter(struct gve_priv * priv,struct gve_tx_ring * tx)880 u32 gve_tx_load_event_counter(struct gve_priv *priv,
881 			      struct gve_tx_ring *tx)
882 {
883 	u32 counter_index = be32_to_cpu(tx->q_resources->counter_index);
884 	__be32 counter = READ_ONCE(priv->counter_array[counter_index]);
885 
886 	return be32_to_cpu(counter);
887 }
888 
gve_xsk_tx(struct gve_priv * priv,struct gve_tx_ring * tx,int budget)889 static int gve_xsk_tx(struct gve_priv *priv, struct gve_tx_ring *tx,
890 		      int budget)
891 {
892 	struct xdp_desc desc;
893 	int sent = 0, nsegs;
894 	void *data;
895 
896 	spin_lock(&tx->xdp_lock);
897 	while (sent < budget) {
898 		if (!gve_can_tx(tx, GVE_TX_START_THRESH))
899 			goto out;
900 
901 		if (!xsk_tx_peek_desc(tx->xsk_pool, &desc)) {
902 			tx->xdp_xsk_done = tx->xdp_xsk_wakeup;
903 			goto out;
904 		}
905 
906 		data = xsk_buff_raw_get_data(tx->xsk_pool, desc.addr);
907 		nsegs = gve_tx_fill_xdp(priv, tx, data, desc.len, NULL, true);
908 		tx->req += nsegs;
909 		sent++;
910 	}
911 out:
912 	if (sent > 0) {
913 		gve_tx_put_doorbell(priv, tx->q_resources, tx->req);
914 		xsk_tx_release(tx->xsk_pool);
915 	}
916 	spin_unlock(&tx->xdp_lock);
917 	return sent;
918 }
919 
gve_xdp_poll(struct gve_notify_block * block,int budget)920 bool gve_xdp_poll(struct gve_notify_block *block, int budget)
921 {
922 	struct gve_priv *priv = block->priv;
923 	struct gve_tx_ring *tx = block->tx;
924 	u32 nic_done;
925 	bool repoll;
926 	u32 to_do;
927 
928 	/* Find out how much work there is to be done */
929 	nic_done = gve_tx_load_event_counter(priv, tx);
930 	to_do = min_t(u32, (nic_done - tx->done), budget);
931 	gve_clean_xdp_done(priv, tx, to_do);
932 	repoll = nic_done != tx->done;
933 
934 	if (tx->xsk_pool) {
935 		int sent = gve_xsk_tx(priv, tx, budget);
936 
937 		u64_stats_update_begin(&tx->statss);
938 		tx->xdp_xsk_sent += sent;
939 		u64_stats_update_end(&tx->statss);
940 		repoll |= (sent == budget);
941 		if (xsk_uses_need_wakeup(tx->xsk_pool))
942 			xsk_set_tx_need_wakeup(tx->xsk_pool);
943 	}
944 
945 	/* If we still have work we want to repoll */
946 	return repoll;
947 }
948 
gve_tx_poll(struct gve_notify_block * block,int budget)949 bool gve_tx_poll(struct gve_notify_block *block, int budget)
950 {
951 	struct gve_priv *priv = block->priv;
952 	struct gve_tx_ring *tx = block->tx;
953 	u32 nic_done;
954 	u32 to_do;
955 
956 	/* If budget is 0, do all the work */
957 	if (budget == 0)
958 		budget = INT_MAX;
959 
960 	/* In TX path, it may try to clean completed pkts in order to xmit,
961 	 * to avoid cleaning conflict, use spin_lock(), it yields better
962 	 * concurrency between xmit/clean than netif's lock.
963 	 */
964 	spin_lock(&tx->clean_lock);
965 	/* Find out how much work there is to be done */
966 	nic_done = gve_tx_load_event_counter(priv, tx);
967 	to_do = min_t(u32, (nic_done - tx->done), budget);
968 	gve_clean_tx_done(priv, tx, to_do, true);
969 	spin_unlock(&tx->clean_lock);
970 	/* If we still have work we want to repoll */
971 	return nic_done != tx->done;
972 }
973 
gve_tx_clean_pending(struct gve_priv * priv,struct gve_tx_ring * tx)974 bool gve_tx_clean_pending(struct gve_priv *priv, struct gve_tx_ring *tx)
975 {
976 	u32 nic_done = gve_tx_load_event_counter(priv, tx);
977 
978 	return nic_done != tx->done;
979 }
980