nfp: add support for sending control messages via mailbox

FW may prefer to handle some communication via a mailbox
or the vNIC may simply not have a control queue (VFs).
Add a way of exchanging ccm-compatible messages via a
mailbox.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 591 insertions, 0 deletions

diff --git a/drivers/net/ethernet/netronome/nfp/ccm_mbox.c b/drivers/net/ethernet/netronome/nfp/ccm_mbox.c
new file mode 100644
index 000000000000..e5acd96c3335
--- /dev/null
+++ b/drivers/net/ethernet/netronome/nfp/ccm_mbox.c
@@ -0,0 +1,591 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+/* Copyright (C) 2019 Netronome Systems, Inc. */
+
+#include <linux/bitfield.h>
+#include <linux/io.h>
+#include <linux/skbuff.h>
+
+#include "ccm.h"
+#include "nfp_net.h"
+
+/* CCM messages via the mailbox.  CMSGs get wrapped into simple TLVs
+ * and copied into the mailbox.  Multiple messages can be copied to
+ * form a batch.  Threads come in with CMSG formed in an skb, then
+ * enqueue that skb onto the request queue.  If threads skb is first
+ * in queue this thread will handle the mailbox operation.  It copies
+ * up to 16 messages into the mailbox (making sure that both requests
+ * and replies will fit.  After FW is done processing the batch it
+ * copies the data out and wakes waiting threads.
+ * If a thread is waiting it either gets its the message completed
+ * (response is copied into the same skb as the request, overwriting
+ * it), or becomes the first in queue.
+ * Completions and next-to-run are signaled via the control buffer
+ * to limit potential cache line bounces.
+ */
+
+#define NFP_CCM_MBOX_BATCH_LIMIT	16
+#define NFP_CCM_TIMEOUT			(NFP_NET_POLL_TIMEOUT * 1000)
+#define NFP_CCM_MAX_QLEN		256
+
+enum nfp_net_mbox_cmsg_state {
+	NFP_NET_MBOX_CMSG_STATE_QUEUED,
+	NFP_NET_MBOX_CMSG_STATE_NEXT,
+	NFP_NET_MBOX_CMSG_STATE_BUSY,
+	NFP_NET_MBOX_CMSG_STATE_REPLY_FOUND,
+	NFP_NET_MBOX_CMSG_STATE_DONE,
+};
+
+/**
+ * struct nfp_ccm_mbox_skb_cb - CCM mailbox specific info
+ * @state:	processing state (/stage) of the message
+ * @err:	error encountered during processing if any
+ * @max_len:	max(request_len, reply_len)
+ * @exp_reply:	expected reply length (0 means don't validate)
+ */
+struct nfp_ccm_mbox_cmsg_cb {
+	enum nfp_net_mbox_cmsg_state state;
+	int err;
+	unsigned int max_len;
+	unsigned int exp_reply;
+};
+
+static u32 nfp_ccm_mbox_max_msg(struct nfp_net *nn)
+{
+	return round_down(nn->tlv_caps.mbox_len, 4) -
+		NFP_NET_CFG_MBOX_SIMPLE_VAL - /* common mbox command header */
+		4 * 2; /* Msg TLV plus End TLV headers */
+}
+
+static void
+nfp_ccm_mbox_msg_init(struct sk_buff *skb, unsigned int exp_reply, int max_len)
+{
+	struct nfp_ccm_mbox_cmsg_cb *cb = (void *)skb->cb;
+
+	cb->state = NFP_NET_MBOX_CMSG_STATE_QUEUED;
+	cb->err = 0;
+	cb->max_len = max_len;
+	cb->exp_reply = exp_reply;
+}
+
+static int nfp_ccm_mbox_maxlen(const struct sk_buff *skb)
+{
+	struct nfp_ccm_mbox_cmsg_cb *cb = (void *)skb->cb;
+
+	return cb->max_len;
+}
+
+static bool nfp_ccm_mbox_done(struct sk_buff *skb)
+{
+	struct nfp_ccm_mbox_cmsg_cb *cb = (void *)skb->cb;
+
+	return cb->state == NFP_NET_MBOX_CMSG_STATE_DONE;
+}
+
+static bool nfp_ccm_mbox_in_progress(struct sk_buff *skb)
+{
+	struct nfp_ccm_mbox_cmsg_cb *cb = (void *)skb->cb;
+
+	return cb->state != NFP_NET_MBOX_CMSG_STATE_QUEUED &&
+	       cb->state != NFP_NET_MBOX_CMSG_STATE_NEXT;
+}
+
+static void nfp_ccm_mbox_set_busy(struct sk_buff *skb)
+{
+	struct nfp_ccm_mbox_cmsg_cb *cb = (void *)skb->cb;
+
+	cb->state = NFP_NET_MBOX_CMSG_STATE_BUSY;
+}
+
+static bool nfp_ccm_mbox_is_first(struct nfp_net *nn, struct sk_buff *skb)
+{
+	return skb_queue_is_first(&nn->mbox_cmsg.queue, skb);
+}
+
+static bool nfp_ccm_mbox_should_run(struct nfp_net *nn, struct sk_buff *skb)
+{
+	struct nfp_ccm_mbox_cmsg_cb *cb = (void *)skb->cb;
+
+	return cb->state == NFP_NET_MBOX_CMSG_STATE_NEXT;
+}
+
+static void nfp_ccm_mbox_mark_next_runner(struct nfp_net *nn)
+{
+	struct nfp_ccm_mbox_cmsg_cb *cb;
+	struct sk_buff *skb;
+
+	skb = skb_peek(&nn->mbox_cmsg.queue);
+	if (!skb)
+		return;
+
+	cb = (void *)skb->cb;
+	cb->state = NFP_NET_MBOX_CMSG_STATE_NEXT;
+}
+
+static void
+nfp_ccm_mbox_write_tlv(struct nfp_net *nn, u32 off, u32 type, u32 len)
+{
+	nn_writel(nn, off,
+		  FIELD_PREP(NFP_NET_MBOX_TLV_TYPE, type) |
+		  FIELD_PREP(NFP_NET_MBOX_TLV_LEN, len));
+}
+
+static void nfp_ccm_mbox_copy_in(struct nfp_net *nn, struct sk_buff *last)
+{
+	struct sk_buff *skb;
+	int reserve, i, cnt;
+	__be32 *data;
+	u32 off, len;
+
+	off = nn->tlv_caps.mbox_off + NFP_NET_CFG_MBOX_SIMPLE_VAL;
+	skb = __skb_peek(&nn->mbox_cmsg.queue);
+	while (true) {
+		nfp_ccm_mbox_write_tlv(nn, off, NFP_NET_MBOX_TLV_TYPE_MSG,
+				       skb->len);
+		off += 4;
+
+		/* Write data word by word, skb->data should be aligned */
+		data = (__be32 *)skb->data;
+		cnt = skb->len / 4;
+		for (i = 0 ; i < cnt; i++) {
+			nn_writel(nn, off, be32_to_cpu(data[i]));
+			off += 4;
+		}
+		if (skb->len & 3) {
+			__be32 tmp = 0;
+
+			memcpy(&tmp, &data[i], skb->len & 3);
+			nn_writel(nn, off, be32_to_cpu(tmp));
+			off += 4;
+		}
+
+		/* Reserve space if reply is bigger */
+		len = round_up(skb->len, 4);
+		reserve = nfp_ccm_mbox_maxlen(skb) - len;
+		if (reserve > 0) {
+			nfp_ccm_mbox_write_tlv(nn, off,
+					       NFP_NET_MBOX_TLV_TYPE_RESV,
+					       reserve);
+			off += 4 + reserve;
+		}
+
+		if (skb == last)
+			break;
+		skb = skb_queue_next(&nn->mbox_cmsg.queue, skb);
+	}
+
+	nfp_ccm_mbox_write_tlv(nn, off, NFP_NET_MBOX_TLV_TYPE_END, 0);
+}
+
+static struct sk_buff *
+nfp_ccm_mbox_find_req(struct nfp_net *nn, __be16 tag, struct sk_buff *last)
+{
+	struct sk_buff *skb;
+
+	skb = __skb_peek(&nn->mbox_cmsg.queue);
+	while (true) {
+		if (__nfp_ccm_get_tag(skb) == tag)
+			return skb;
+
+		if (skb == last)
+			return NULL;
+		skb = skb_queue_next(&nn->mbox_cmsg.queue, skb);
+	}
+}
+
+static void nfp_ccm_mbox_copy_out(struct nfp_net *nn, struct sk_buff *last)
+{
+	struct nfp_ccm_mbox_cmsg_cb *cb;
+	u8 __iomem *data, *end;
+	struct sk_buff *skb;
+
+	data = nn->dp.ctrl_bar + nn->tlv_caps.mbox_off +
+		NFP_NET_CFG_MBOX_SIMPLE_VAL;
+	end = data + nn->tlv_caps.mbox_len;
+
+	while (true) {
+		unsigned int length, offset, type;
+		struct nfp_ccm_hdr hdr;
+		__be32 *skb_data;
+		u32 tlv_hdr;
+		int i, cnt;
+
+		tlv_hdr = readl(data);
+		type = FIELD_GET(NFP_NET_MBOX_TLV_TYPE, tlv_hdr);
+		length = FIELD_GET(NFP_NET_MBOX_TLV_LEN, tlv_hdr);
+		offset = data - nn->dp.ctrl_bar;
+
+		/* Advance past the header */
+		data += 4;
+
+		if (data + length > end) {
+			nn_dp_warn(&nn->dp, "mailbox oversized TLV type:%d offset:%u len:%u\n",
+				   type, offset, length);
+			break;
+		}
+
+		if (type == NFP_NET_MBOX_TLV_TYPE_END)
+			break;
+		if (type == NFP_NET_MBOX_TLV_TYPE_RESV)
+			goto next_tlv;
+		if (type != NFP_NET_MBOX_TLV_TYPE_MSG &&
+		    type != NFP_NET_MBOX_TLV_TYPE_MSG_NOSUP) {
+			nn_dp_warn(&nn->dp, "mailbox unknown TLV type:%d offset:%u len:%u\n",
+				   type, offset, length);
+			break;
+		}
+
+		if (length < 4) {
+			nn_dp_warn(&nn->dp, "mailbox msg too short to contain header TLV type:%d offset:%u len:%u\n",
+				   type, offset, length);
+			break;
+		}
+
+		hdr.raw = cpu_to_be32(readl(data));
+
+		skb = nfp_ccm_mbox_find_req(nn, hdr.tag, last);
+		if (!skb) {
+			nn_dp_warn(&nn->dp, "mailbox request not found:%u\n",
+				   be16_to_cpu(hdr.tag));
+			break;
+		}
+		cb = (void *)skb->cb;
+
+		if (type == NFP_NET_MBOX_TLV_TYPE_MSG_NOSUP) {
+			nn_dp_warn(&nn->dp,
+				   "mailbox msg not supported type:%d\n",
+				   nfp_ccm_get_type(skb));
+			cb->err = -EIO;
+			goto next_tlv;
+		}
+
+		if (hdr.type != __NFP_CCM_REPLY(nfp_ccm_get_type(skb))) {
+			nn_dp_warn(&nn->dp, "mailbox msg reply wrong type:%u expected:%lu\n",
+				   hdr.type,
+				   __NFP_CCM_REPLY(nfp_ccm_get_type(skb)));
+			cb->err = -EIO;
+			goto next_tlv;
+		}
+		if (cb->exp_reply && length != cb->exp_reply) {
+			nn_dp_warn(&nn->dp, "mailbox msg reply wrong size type:%u expected:%u have:%u\n",
+				   hdr.type, length, cb->exp_reply);
+			cb->err = -EIO;
+			goto next_tlv;
+		}
+		if (length > cb->max_len) {
+			nn_dp_warn(&nn->dp, "mailbox msg oversized reply type:%u max:%u have:%u\n",
+				   hdr.type, cb->max_len, length);
+			cb->err = -EIO;
+			goto next_tlv;
+		}
+
+		if (length <= skb->len)
+			__skb_trim(skb, length);
+		else
+			skb_put(skb, length - skb->len);
+
+		/* We overcopy here slightly, but that's okay, the skb is large
+		 * enough, and the garbage will be ignored (beyond skb->len).
+		 */
+		skb_data = (__be32 *)skb->data;
+		memcpy(skb_data, &hdr, 4);
+
+		cnt = DIV_ROUND_UP(length, 4);
+		for (i = 1 ; i < cnt; i++)
+			skb_data[i] = cpu_to_be32(readl(data + i * 4));
+
+		cb->state = NFP_NET_MBOX_CMSG_STATE_REPLY_FOUND;
+next_tlv:
+		data += round_up(length, 4);
+		if (data + 4 > end) {
+			nn_dp_warn(&nn->dp,
+				   "reached end of MBOX without END TLV\n");
+			break;
+		}
+	}
+
+	smp_wmb(); /* order the skb->data vs. cb->state */
+	spin_lock_bh(&nn->mbox_cmsg.queue.lock);
+	do {
+		skb = __skb_dequeue(&nn->mbox_cmsg.queue);
+		cb = (void *)skb->cb;
+
+		if (cb->state != NFP_NET_MBOX_CMSG_STATE_REPLY_FOUND) {
+			cb->err = -ENOENT;
+			smp_wmb(); /* order the cb->err vs. cb->state */
+		}
+		cb->state = NFP_NET_MBOX_CMSG_STATE_DONE;
+	} while (skb != last);
+
+	nfp_ccm_mbox_mark_next_runner(nn);
+	spin_unlock_bh(&nn->mbox_cmsg.queue.lock);
+}
+
+static void
+nfp_ccm_mbox_mark_all_err(struct nfp_net *nn, struct sk_buff *last, int err)
+{
+	struct nfp_ccm_mbox_cmsg_cb *cb;
+	struct sk_buff *skb;
+
+	spin_lock_bh(&nn->mbox_cmsg.queue.lock);
+	do {
+		skb = __skb_dequeue(&nn->mbox_cmsg.queue);
+		cb = (void *)skb->cb;
+
+		cb->err = err;
+		smp_wmb(); /* order the cb->err vs. cb->state */
+		cb->state = NFP_NET_MBOX_CMSG_STATE_DONE;
+	} while (skb != last);
+
+	nfp_ccm_mbox_mark_next_runner(nn);
+	spin_unlock_bh(&nn->mbox_cmsg.queue.lock);
+}
+
+static void nfp_ccm_mbox_run_queue_unlock(struct nfp_net *nn)
+	__releases(&nn->mbox_cmsg.queue.lock)
+{
+	int space = nn->tlv_caps.mbox_len - NFP_NET_CFG_MBOX_SIMPLE_VAL;
+	struct sk_buff *skb, *last;
+	int cnt, err;
+
+	space -= 4; /* for End TLV */
+
+	/* First skb must fit, because it's ours and we checked it fits */
+	cnt = 1;
+	last = skb = __skb_peek(&nn->mbox_cmsg.queue);
+	space -= 4 + nfp_ccm_mbox_maxlen(skb);
+
+	while (!skb_queue_is_last(&nn->mbox_cmsg.queue, last)) {
+		skb = skb_queue_next(&nn->mbox_cmsg.queue, last);
+		space -= 4 + nfp_ccm_mbox_maxlen(skb);
+		if (space < 0)
+			break;
+		last = skb;
+		nfp_ccm_mbox_set_busy(skb);
+		cnt++;
+		if (cnt == NFP_CCM_MBOX_BATCH_LIMIT)
+			break;
+	}
+	spin_unlock_bh(&nn->mbox_cmsg.queue.lock);
+
+	/* Now we own all skb's marked in progress, new requests may arrive
+	 * at the end of the queue.
+	 */
+
+	nn_ctrl_bar_lock(nn);
+
+	nfp_ccm_mbox_copy_in(nn, last);
+
+	err = nfp_net_mbox_reconfig(nn, NFP_NET_CFG_MBOX_CMD_TLV_CMSG);
+	if (!err)
+		nfp_ccm_mbox_copy_out(nn, last);
+	else
+		nfp_ccm_mbox_mark_all_err(nn, last, -EIO);
+
+	nn_ctrl_bar_unlock(nn);
+
+	wake_up_all(&nn->mbox_cmsg.wq);
+}
+
+static int nfp_ccm_mbox_skb_return(struct sk_buff *skb)
+{
+	struct nfp_ccm_mbox_cmsg_cb *cb = (void *)skb->cb;
+
+	if (cb->err)
+		dev_kfree_skb_any(skb);
+	return cb->err;
+}
+
+/* If wait timed out but the command is already in progress we have
+ * to wait until it finishes.  Runners has ownership of the skbs marked
+ * as busy.
+ */
+static int
+nfp_ccm_mbox_unlink_unlock(struct nfp_net *nn, struct sk_buff *skb,
+			   enum nfp_ccm_type type)
+	__releases(&nn->mbox_cmsg.queue.lock)
+{
+	bool was_first;
+
+	if (nfp_ccm_mbox_in_progress(skb)) {
+		spin_unlock_bh(&nn->mbox_cmsg.queue.lock);
+
+		wait_event(nn->mbox_cmsg.wq, nfp_ccm_mbox_done(skb));
+		smp_rmb(); /* pairs with smp_wmb() after data is written */
+		return nfp_ccm_mbox_skb_return(skb);
+	}
+
+	was_first = nfp_ccm_mbox_should_run(nn, skb);
+	__skb_unlink(skb, &nn->mbox_cmsg.queue);
+	if (was_first)
+		nfp_ccm_mbox_mark_next_runner(nn);
+
+	spin_unlock_bh(&nn->mbox_cmsg.queue.lock);
+
+	if (was_first)
+		wake_up_all(&nn->mbox_cmsg.wq);
+
+	nn_dp_warn(&nn->dp, "time out waiting for mbox response to 0x%02x\n",
+		   type);
+	return -ETIMEDOUT;
+}
+
+static int
+nfp_ccm_mbox_msg_prepare(struct nfp_net *nn, struct sk_buff *skb,
+			 enum nfp_ccm_type type,
+			 unsigned int reply_size, unsigned int max_reply_size,
+			 gfp_t flags)
+{
+	const unsigned int mbox_max = nfp_ccm_mbox_max_msg(nn);
+	unsigned int max_len;
+	ssize_t undersize;
+	int err;
+
+	if (unlikely(!(nn->tlv_caps.mbox_cmsg_types & BIT(type)))) {
+		nn_dp_warn(&nn->dp,
+			   "message type %d not supported by mailbox\n", type);
+		return -EINVAL;
+	}
+
+	/* If the reply size is unknown assume it will take the entire
+	 * mailbox, the callers should do their best for this to never
+	 * happen.
+	 */
+	if (!max_reply_size)
+		max_reply_size = mbox_max;
+	max_reply_size = round_up(max_reply_size, 4);
+
+	/* Make sure we can fit the entire reply into the skb,
+	 * and that we don't have to slow down the mbox handler
+	 * with allocations.
+	 */
+	undersize = max_reply_size - (skb_end_pointer(skb) - skb->data);
+	if (undersize > 0) {
+		err = pskb_expand_head(skb, 0, undersize, flags);
+		if (err) {
+			nn_dp_warn(&nn->dp,
+				   "can't allocate reply buffer for mailbox\n");
+			return err;
+		}
+	}
+
+	/* Make sure that request and response both fit into the mailbox */
+	max_len = max(max_reply_size, round_up(skb->len, 4));
+	if (max_len > mbox_max) {
+		nn_dp_warn(&nn->dp,
+			   "message too big for tha mailbox: %u/%u vs %u\n",
+			   skb->len, max_reply_size, mbox_max);
+		return -EMSGSIZE;
+	}
+
+	nfp_ccm_mbox_msg_init(skb, reply_size, max_len);
+
+	return 0;
+}
+
+static int
+nfp_ccm_mbox_msg_enqueue(struct nfp_net *nn, struct sk_buff *skb,
+			 enum nfp_ccm_type type)
+{
+	struct nfp_ccm_hdr *hdr;
+
+	assert_spin_locked(&nn->mbox_cmsg.queue.lock);
+
+	if (nn->mbox_cmsg.queue.qlen >= NFP_CCM_MAX_QLEN) {
+		nn_dp_warn(&nn->dp, "mailbox request queue too long\n");
+		return -EBUSY;
+	}
+
+	hdr = (void *)skb->data;
+	hdr->ver = NFP_CCM_ABI_VERSION;
+	hdr->type = type;
+	hdr->tag = cpu_to_be16(nn->mbox_cmsg.tag++);
+
+	__skb_queue_tail(&nn->mbox_cmsg.queue, skb);
+
+	return 0;
+}
+
+int nfp_ccm_mbox_communicate(struct nfp_net *nn, struct sk_buff *skb,
+			     enum nfp_ccm_type type,
+			     unsigned int reply_size,
+			     unsigned int max_reply_size)
+{
+	int err;
+
+	err = nfp_ccm_mbox_msg_prepare(nn, skb, type, reply_size,
+				       max_reply_size, GFP_KERNEL);
+	if (err)
+		goto err_free_skb;
+
+	spin_lock_bh(&nn->mbox_cmsg.queue.lock);
+
+	err = nfp_ccm_mbox_msg_enqueue(nn, skb, type);
+	if (err)
+		goto err_unlock;
+
+	/* First in queue takes the mailbox lock and processes the batch */
+	if (!nfp_ccm_mbox_is_first(nn, skb)) {
+		bool to;
+
+		spin_unlock_bh(&nn->mbox_cmsg.queue.lock);
+
+		to = !wait_event_timeout(nn->mbox_cmsg.wq,
+					 nfp_ccm_mbox_done(skb) ||
+					 nfp_ccm_mbox_should_run(nn, skb),
+					 msecs_to_jiffies(NFP_CCM_TIMEOUT));
+
+		/* fast path for those completed by another thread */
+		if (nfp_ccm_mbox_done(skb)) {
+			smp_rmb(); /* pairs with wmb after data is written */
+			return nfp_ccm_mbox_skb_return(skb);
+		}
+
+		spin_lock_bh(&nn->mbox_cmsg.queue.lock);
+
+		if (!nfp_ccm_mbox_is_first(nn, skb)) {
+			WARN_ON(!to);
+
+			err = nfp_ccm_mbox_unlink_unlock(nn, skb, type);
+			if (err)
+				goto err_free_skb;
+			return 0;
+		}
+	}
+
+	/* run queue expects the lock held */
+	nfp_ccm_mbox_run_queue_unlock(nn);
+	return nfp_ccm_mbox_skb_return(skb);
+
+err_unlock:
+	spin_unlock_bh(&nn->mbox_cmsg.queue.lock);
+err_free_skb:
+	dev_kfree_skb_any(skb);
+	return err;
+}
+
+struct sk_buff *
+nfp_ccm_mbox_alloc(struct nfp_net *nn, unsigned int req_size,
+		   unsigned int reply_size, gfp_t flags)
+{
+	unsigned int max_size;
+	struct sk_buff *skb;
+
+	if (!reply_size)
+		max_size = nfp_ccm_mbox_max_msg(nn);
+	else
+		max_size = max(req_size, reply_size);
+	max_size = round_up(max_size, 4);
+
+	skb = alloc_skb(max_size, flags);
+	if (!skb)
+		return NULL;
+
+	skb_put(skb, req_size);
+
+	return skb;
+}
+
+bool nfp_ccm_mbox_fits(struct nfp_net *nn, unsigned int size)
+{
+	return nfp_ccm_mbox_max_msg(nn) >= size;
+}