2 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
6 * (C) Copyright 2020 Hewlett Packard Enterprise Development LP
7 * Copyright (C) 1999-2009 Silicon Graphics, Inc. All rights reserved.
11 * Cross Partition Network Interface (XPNET) support
13 * XPNET provides a virtual network layered on top of the Cross
14 * Partition communication layer.
16 * XPNET provides direct point-to-point and broadcast-like support
17 * for an ethernet-like device. The ethernet broadcast medium is
18 * replaced with a point-to-point message structure which passes
19 * pointers to a DMA-capable block that a remote partition should
20 * retrieve and pass to the upper level networking layer.
24 #include <linux/slab.h>
25 #include <linux/module.h>
26 #include <linux/netdevice.h>
27 #include <linux/etherdevice.h>
31 * The message payload transferred by XPC.
33 * buf_pa is the physical address where the DMA should pull from.
35 * NOTE: for performance reasons, buf_pa should _ALWAYS_ begin on a
36 * cacheline boundary. To accomplish this, we record the number of
37 * bytes from the beginning of the first cacheline to the first useful
38 * byte of the skb (leadin_ignore) and the number of bytes from the
39 * last useful byte of the skb to the end of the last cacheline
42 * size is the number of bytes to transfer which includes the skb->len
43 * (useful bytes of the senders skb) plus the leadin and tailout
45 struct xpnet_message {
46 u16 version; /* Version for this message */
47 u16 embedded_bytes; /* #of bytes embedded in XPC message */
48 u32 magic; /* Special number indicating this is xpnet */
49 unsigned long buf_pa; /* phys address of buffer to retrieve */
50 u32 size; /* #of bytes in buffer */
51 u8 leadin_ignore; /* #of bytes to ignore at the beginning */
52 u8 tailout_ignore; /* #of bytes to ignore at the end */
53 unsigned char data; /* body of small packets */
57 * Determine the size of our message, the cacheline aligned size,
58 * and then the number of message will request from XPC.
60 * XPC expects each message to exist in an individual cacheline.
62 #define XPNET_MSG_SIZE XPC_MSG_PAYLOAD_MAX_SIZE
63 #define XPNET_MSG_DATA_MAX \
64 (XPNET_MSG_SIZE - offsetof(struct xpnet_message, data))
65 #define XPNET_MSG_NENTRIES (PAGE_SIZE / XPC_MSG_MAX_SIZE)
67 #define XPNET_MAX_KTHREADS (XPNET_MSG_NENTRIES + 1)
68 #define XPNET_MAX_IDLE_KTHREADS (XPNET_MSG_NENTRIES + 1)
71 * Version number of XPNET implementation. XPNET can always talk to versions
72 * with same major #, and never talk to versions with a different version.
74 #define _XPNET_VERSION(_major, _minor) (((_major) << 4) | (_minor))
75 #define XPNET_VERSION_MAJOR(_v) ((_v) >> 4)
76 #define XPNET_VERSION_MINOR(_v) ((_v) & 0xf)
78 #define XPNET_VERSION _XPNET_VERSION(1, 0) /* version 1.0 */
79 #define XPNET_VERSION_EMBED _XPNET_VERSION(1, 1) /* version 1.1 */
80 #define XPNET_MAGIC 0x88786984 /* "XNET" */
82 #define XPNET_VALID_MSG(_m) \
83 ((XPNET_VERSION_MAJOR(_m->version) == XPNET_VERSION_MAJOR(XPNET_VERSION)) \
84 && (msg->magic == XPNET_MAGIC))
86 #define XPNET_DEVICE_NAME "xp0"
89 * When messages are queued with xpc_send_notify, a kmalloc'd buffer
90 * of the following type is passed as a notification cookie. When the
91 * notification function is called, we use the cookie to decide
92 * whether all outstanding message sends have completed. The skb can
95 struct xpnet_pending_msg {
100 static struct net_device *xpnet_device;
103 * When we are notified of other partitions activating, we add them to
104 * our bitmask of partitions to which we broadcast.
106 static unsigned long *xpnet_broadcast_partitions;
108 static DEFINE_SPINLOCK(xpnet_broadcast_lock);
111 * Since the Block Transfer Engine (BTE) is being used for the transfer
112 * and it relies upon cache-line size transfers, we need to reserve at
113 * least one cache-line for head and tail alignment. The BTE is
114 * limited to 8MB transfers.
116 * Testing has shown that changing MTU to greater than 64KB has no effect
117 * on TCP as the two sides negotiate a Max Segment Size that is limited
118 * to 64K. Other protocols May use packets greater than this, but for
119 * now, the default is 64KB.
121 #define XPNET_MAX_MTU (0x800000UL - L1_CACHE_BYTES)
122 /* 68 comes from min TCP+IP+MAC header */
123 #define XPNET_MIN_MTU 68
124 /* 32KB has been determined to be the ideal */
125 #define XPNET_DEF_MTU (0x8000UL)
128 * The partid is encapsulated in the MAC address beginning in the following
129 * octet and it consists of two octets.
131 #define XPNET_PARTID_OCTET 2
133 /* Define the XPNET debug device structures to be used with dev_dbg() et al */
135 static struct device_driver xpnet_dbg_name = {
139 static struct device xpnet_dbg_subname = {
140 .init_name = "", /* set to "" */
141 .driver = &xpnet_dbg_name
144 static struct device *xpnet = &xpnet_dbg_subname;
147 * Packet was recevied by XPC and forwarded to us.
150 xpnet_receive(short partid, int channel, struct xpnet_message *msg)
156 if (!XPNET_VALID_MSG(msg)) {
158 * Packet with a different XPC version. Ignore.
160 xpc_received(partid, channel, (void *)msg);
162 xpnet_device->stats.rx_errors++;
166 dev_dbg(xpnet, "received 0x%lx, %d, %d, %d\n", msg->buf_pa, msg->size,
167 msg->leadin_ignore, msg->tailout_ignore);
169 /* reserve an extra cache line */
170 skb = dev_alloc_skb(msg->size + L1_CACHE_BYTES);
172 dev_err(xpnet, "failed on dev_alloc_skb(%d)\n",
173 msg->size + L1_CACHE_BYTES);
175 xpc_received(partid, channel, (void *)msg);
177 xpnet_device->stats.rx_errors++;
183 * The allocated skb has some reserved space.
184 * In order to use xp_remote_memcpy(), we need to get the
185 * skb->data pointer moved forward.
187 skb_reserve(skb, (L1_CACHE_BYTES - ((u64)skb->data &
188 (L1_CACHE_BYTES - 1)) +
189 msg->leadin_ignore));
192 * Update the tail pointer to indicate data actually
195 skb_put(skb, (msg->size - msg->leadin_ignore - msg->tailout_ignore));
198 * Move the data over from the other side.
200 if ((XPNET_VERSION_MINOR(msg->version) == 1) &&
201 (msg->embedded_bytes != 0)) {
202 dev_dbg(xpnet, "copying embedded message. memcpy(0x%p, 0x%p, "
203 "%lu)\n", skb->data, &msg->data,
204 (size_t)msg->embedded_bytes);
206 skb_copy_to_linear_data(skb, &msg->data,
207 (size_t)msg->embedded_bytes);
209 dst = (void *)((u64)skb->data & ~(L1_CACHE_BYTES - 1));
210 dev_dbg(xpnet, "transferring buffer to the skb->data area;\n\t"
211 "xp_remote_memcpy(0x%p, 0x%p, %u)\n", dst,
212 (void *)msg->buf_pa, msg->size);
214 ret = xp_remote_memcpy(xp_pa(dst), msg->buf_pa, msg->size);
215 if (ret != xpSuccess) {
217 * !!! Need better way of cleaning skb. Currently skb
218 * !!! appears in_use and we can't just call
221 dev_err(xpnet, "xp_remote_memcpy(0x%p, 0x%p, 0x%x) "
222 "returned error=0x%x\n", dst,
223 (void *)msg->buf_pa, msg->size, ret);
225 xpc_received(partid, channel, (void *)msg);
227 xpnet_device->stats.rx_errors++;
233 dev_dbg(xpnet, "<skb->head=0x%p skb->data=0x%p skb->tail=0x%p "
234 "skb->end=0x%p skb->len=%d\n", (void *)skb->head,
235 (void *)skb->data, skb_tail_pointer(skb), skb_end_pointer(skb),
238 skb->protocol = eth_type_trans(skb, xpnet_device);
239 skb->ip_summed = CHECKSUM_UNNECESSARY;
241 dev_dbg(xpnet, "passing skb to network layer\n"
242 "\tskb->head=0x%p skb->data=0x%p skb->tail=0x%p "
243 "skb->end=0x%p skb->len=%d\n",
244 (void *)skb->head, (void *)skb->data, skb_tail_pointer(skb),
245 skb_end_pointer(skb), skb->len);
247 xpnet_device->stats.rx_packets++;
248 xpnet_device->stats.rx_bytes += skb->len + ETH_HLEN;
251 xpc_received(partid, channel, (void *)msg);
255 * This is the handler which XPC calls during any sort of change in
256 * state or message reception on a connection.
259 xpnet_connection_activity(enum xp_retval reason, short partid, int channel,
260 void *data, void *key)
262 DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
263 DBUG_ON(channel != XPC_NET_CHANNEL);
266 case xpMsgReceived: /* message received */
267 DBUG_ON(data == NULL);
269 xpnet_receive(partid, channel, (struct xpnet_message *)data);
272 case xpConnected: /* connection completed to a partition */
273 spin_lock_bh(&xpnet_broadcast_lock);
274 __set_bit(partid, xpnet_broadcast_partitions);
275 spin_unlock_bh(&xpnet_broadcast_lock);
277 netif_carrier_on(xpnet_device);
279 dev_dbg(xpnet, "%s connected to partition %d\n",
280 xpnet_device->name, partid);
284 spin_lock_bh(&xpnet_broadcast_lock);
285 __clear_bit(partid, xpnet_broadcast_partitions);
286 spin_unlock_bh(&xpnet_broadcast_lock);
288 if (bitmap_empty((unsigned long *)xpnet_broadcast_partitions,
289 xp_max_npartitions)) {
290 netif_carrier_off(xpnet_device);
293 dev_dbg(xpnet, "%s disconnected from partition %d\n",
294 xpnet_device->name, partid);
300 xpnet_dev_open(struct net_device *dev)
304 dev_dbg(xpnet, "calling xpc_connect(%d, 0x%p, NULL, %ld, %ld, %ld, "
305 "%ld)\n", XPC_NET_CHANNEL, xpnet_connection_activity,
306 (unsigned long)XPNET_MSG_SIZE,
307 (unsigned long)XPNET_MSG_NENTRIES,
308 (unsigned long)XPNET_MAX_KTHREADS,
309 (unsigned long)XPNET_MAX_IDLE_KTHREADS);
311 ret = xpc_connect(XPC_NET_CHANNEL, xpnet_connection_activity, NULL,
312 XPNET_MSG_SIZE, XPNET_MSG_NENTRIES,
313 XPNET_MAX_KTHREADS, XPNET_MAX_IDLE_KTHREADS);
314 if (ret != xpSuccess) {
315 dev_err(xpnet, "ifconfig up of %s failed on XPC connect, "
316 "ret=%d\n", dev->name, ret);
321 dev_dbg(xpnet, "ifconfig up of %s; XPC connected\n", dev->name);
327 xpnet_dev_stop(struct net_device *dev)
329 xpc_disconnect(XPC_NET_CHANNEL);
331 dev_dbg(xpnet, "ifconfig down of %s; XPC disconnected\n", dev->name);
337 * Notification that the other end has received the message and
338 * DMA'd the skb information. At this point, they are done with
339 * our side. When all recipients are done processing, we
340 * release the skb and then release our pending message structure.
343 xpnet_send_completed(enum xp_retval reason, short partid, int channel,
346 struct xpnet_pending_msg *queued_msg = (struct xpnet_pending_msg *)__qm;
348 DBUG_ON(queued_msg == NULL);
350 dev_dbg(xpnet, "message to %d notified with reason %d\n",
353 if (atomic_dec_return(&queued_msg->use_count) == 0) {
354 dev_dbg(xpnet, "all acks for skb->head=-x%p\n",
355 (void *)queued_msg->skb->head);
357 dev_kfree_skb_any(queued_msg->skb);
363 xpnet_send(struct sk_buff *skb, struct xpnet_pending_msg *queued_msg,
364 u64 start_addr, u64 end_addr, u16 embedded_bytes, int dest_partid)
366 u8 msg_buffer[XPNET_MSG_SIZE];
367 struct xpnet_message *msg = (struct xpnet_message *)&msg_buffer;
368 u16 msg_size = sizeof(struct xpnet_message);
371 msg->embedded_bytes = embedded_bytes;
372 if (unlikely(embedded_bytes != 0)) {
373 msg->version = XPNET_VERSION_EMBED;
374 dev_dbg(xpnet, "calling memcpy(0x%p, 0x%p, 0x%lx)\n",
375 &msg->data, skb->data, (size_t)embedded_bytes);
376 skb_copy_from_linear_data(skb, &msg->data,
377 (size_t)embedded_bytes);
378 msg_size += embedded_bytes - 1;
380 msg->version = XPNET_VERSION;
382 msg->magic = XPNET_MAGIC;
383 msg->size = end_addr - start_addr;
384 msg->leadin_ignore = (u64)skb->data - start_addr;
385 msg->tailout_ignore = end_addr - (u64)skb_tail_pointer(skb);
386 msg->buf_pa = xp_pa((void *)start_addr);
388 dev_dbg(xpnet, "sending XPC message to %d:%d\n"
389 "msg->buf_pa=0x%lx, msg->size=%u, "
390 "msg->leadin_ignore=%u, msg->tailout_ignore=%u\n",
391 dest_partid, XPC_NET_CHANNEL, msg->buf_pa, msg->size,
392 msg->leadin_ignore, msg->tailout_ignore);
394 atomic_inc(&queued_msg->use_count);
396 ret = xpc_send_notify(dest_partid, XPC_NET_CHANNEL, XPC_NOWAIT, msg,
397 msg_size, xpnet_send_completed, queued_msg);
398 if (unlikely(ret != xpSuccess))
399 atomic_dec(&queued_msg->use_count);
403 * Network layer has formatted a packet (skb) and is ready to place it
404 * "on the wire". Prepare and send an xpnet_message to all partitions
405 * which have connected with us and are targets of this packet.
407 * MAC-NOTE: For the XPNET driver, the MAC address contains the
408 * destination partid. If the destination partid octets are 0xffff,
409 * this packet is to be broadcast to all connected partitions.
412 xpnet_dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
414 struct xpnet_pending_msg *queued_msg;
415 u64 start_addr, end_addr;
417 u16 embedded_bytes = 0;
419 dev_dbg(xpnet, ">skb->head=0x%p skb->data=0x%p skb->tail=0x%p "
420 "skb->end=0x%p skb->len=%d\n", (void *)skb->head,
421 (void *)skb->data, skb_tail_pointer(skb), skb_end_pointer(skb),
424 if (skb->data[0] == 0x33) {
426 return NETDEV_TX_OK; /* nothing needed to be done */
430 * The xpnet_pending_msg tracks how many outstanding
431 * xpc_send_notifies are relying on this skb. When none
432 * remain, release the skb.
434 queued_msg = kmalloc(sizeof(struct xpnet_pending_msg), GFP_ATOMIC);
435 if (queued_msg == NULL) {
436 dev_warn(xpnet, "failed to kmalloc %ld bytes; dropping "
437 "packet\n", sizeof(struct xpnet_pending_msg));
439 dev->stats.tx_errors++;
444 /* get the beginning of the first cacheline and end of last */
445 start_addr = ((u64)skb->data & ~(L1_CACHE_BYTES - 1));
446 end_addr = L1_CACHE_ALIGN((u64)skb_tail_pointer(skb));
448 /* calculate how many bytes to embed in the XPC message */
449 if (unlikely(skb->len <= XPNET_MSG_DATA_MAX)) {
450 /* skb->data does fit so embed */
451 embedded_bytes = skb->len;
455 * Since the send occurs asynchronously, we set the count to one
456 * and begin sending. Any sends that happen to complete before
457 * we are done sending will not free the skb. We will be left
458 * with that task during exit. This also handles the case of
459 * a packet destined for a partition which is no longer up.
461 atomic_set(&queued_msg->use_count, 1);
462 queued_msg->skb = skb;
464 if (skb->data[0] == 0xff) {
465 /* we are being asked to broadcast to all partitions */
466 for_each_set_bit(dest_partid, xpnet_broadcast_partitions,
467 xp_max_npartitions) {
469 xpnet_send(skb, queued_msg, start_addr, end_addr,
470 embedded_bytes, dest_partid);
473 dest_partid = (short)skb->data[XPNET_PARTID_OCTET + 1];
474 dest_partid |= (short)skb->data[XPNET_PARTID_OCTET + 0] << 8;
476 if (dest_partid >= 0 &&
477 dest_partid < xp_max_npartitions &&
478 test_bit(dest_partid, xpnet_broadcast_partitions) != 0) {
480 xpnet_send(skb, queued_msg, start_addr, end_addr,
481 embedded_bytes, dest_partid);
485 dev->stats.tx_packets++;
486 dev->stats.tx_bytes += skb->len;
488 if (atomic_dec_return(&queued_msg->use_count) == 0) {
497 * Deal with transmit timeouts coming from the network layer.
500 xpnet_dev_tx_timeout(struct net_device *dev, unsigned int txqueue)
502 dev->stats.tx_errors++;
505 static const struct net_device_ops xpnet_netdev_ops = {
506 .ndo_open = xpnet_dev_open,
507 .ndo_stop = xpnet_dev_stop,
508 .ndo_start_xmit = xpnet_dev_hard_start_xmit,
509 .ndo_tx_timeout = xpnet_dev_tx_timeout,
510 .ndo_set_mac_address = eth_mac_addr,
511 .ndo_validate_addr = eth_validate_addr,
523 dev_info(xpnet, "registering network device %s\n", XPNET_DEVICE_NAME);
525 xpnet_broadcast_partitions = kcalloc(BITS_TO_LONGS(xp_max_npartitions),
528 if (xpnet_broadcast_partitions == NULL)
532 * use ether_setup() to init the majority of our device
533 * structure and then override the necessary pieces.
535 xpnet_device = alloc_netdev(0, XPNET_DEVICE_NAME, NET_NAME_UNKNOWN,
537 if (xpnet_device == NULL) {
538 kfree(xpnet_broadcast_partitions);
542 netif_carrier_off(xpnet_device);
544 xpnet_device->netdev_ops = &xpnet_netdev_ops;
545 xpnet_device->mtu = XPNET_DEF_MTU;
546 xpnet_device->min_mtu = XPNET_MIN_MTU;
547 xpnet_device->max_mtu = XPNET_MAX_MTU;
549 memset(addr, 0, sizeof(addr));
551 * Multicast assumes the LSB of the first octet is set for multicast
552 * MAC addresses. We chose the first octet of the MAC to be unlikely
553 * to collide with any vendor's officially issued MAC.
555 addr[0] = 0x02; /* locally administered, no OUI */
557 addr[XPNET_PARTID_OCTET + 1] = xp_partition_id;
558 addr[XPNET_PARTID_OCTET + 0] = (xp_partition_id >> 8);
559 eth_hw_addr_set(xpnet_device, addr);
562 * ether_setup() sets this to a multicast device. We are
563 * really not supporting multicast at this time.
565 xpnet_device->flags &= ~IFF_MULTICAST;
568 * No need to checksum as it is a DMA transfer. The BTE will
569 * report an error if the data is not retrievable and the
570 * packet will be dropped.
572 xpnet_device->features = NETIF_F_HW_CSUM;
574 result = register_netdev(xpnet_device);
576 free_netdev(xpnet_device);
577 kfree(xpnet_broadcast_partitions);
583 module_init(xpnet_init);
588 dev_info(xpnet, "unregistering network device %s\n",
589 xpnet_device[0].name);
591 unregister_netdev(xpnet_device);
592 free_netdev(xpnet_device);
593 kfree(xpnet_broadcast_partitions);
596 module_exit(xpnet_exit);
598 MODULE_AUTHOR("Silicon Graphics, Inc.");
599 MODULE_DESCRIPTION("Cross Partition Network adapter (XPNET)");
600 MODULE_LICENSE("GPL");