xen-netback: add control protocol implementation

My recent patch to include/xen/interface/io/netif.h defines a new shared
ring (in addition to the rx and tx rings) for passing control messages
from a VM frontend driver to a backend driver.

A previous patch added the necessary boilerplate for mapping the control
ring from the frontend, should it be created. This patch adds
implementations for each of the defined protocol messages.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/xen-netback/Makefile

 obj-$(CONFIG_XEN_NETDEV_BACKEND) := xen-netback.o
 
-xen-netback-y := netback.o xenbus.o interface.o
+xen-netback-y := netback.o xenbus.o interface.o hash.o

drivers/net/xen-netback/common.h

@@ -220,6 +220,35 @@ struct xenvif_mcast_addr {
 
 #define XEN_NETBK_MCAST_MAX 64
 
+#define XEN_NETBK_MAX_HASH_KEY_SIZE 40
+#define XEN_NETBK_MAX_HASH_MAPPING_SIZE 128
+#define XEN_NETBK_HASH_TAG_SIZE 40
+
+struct xenvif_hash_cache_entry {
+	struct list_head link;
+	struct rcu_head rcu;
+	u8 tag[XEN_NETBK_HASH_TAG_SIZE];
+	unsigned int len;
+	u32 val;
+	int seq;
+};
+
+struct xenvif_hash_cache {
+	spinlock_t lock;
+	struct list_head list;
+	unsigned int count;
+	atomic_t seq;
+};
+
+struct xenvif_hash {
+	unsigned int alg;
+	u32 flags;
+	u8 key[XEN_NETBK_MAX_HASH_KEY_SIZE];
+	u32 mapping[XEN_NETBK_MAX_HASH_MAPPING_SIZE];
+	unsigned int size;
+	struct xenvif_hash_cache cache;
+};
+
 struct xenvif {
 	/* Unique identifier for this interface. */
 	domid_t          domid;
@@ -251,6 +280,8 @@ struct xenvif {
 	unsigned int num_queues; /* active queues, resource allocated */
 	unsigned int stalled_queues;
 
+	struct xenvif_hash hash;
+
 	struct xenbus_watch credit_watch;
 	struct xenbus_watch mcast_ctrl_watch;
 
@@ -353,6 +384,7 @@ extern bool separate_tx_rx_irq;
 extern unsigned int rx_drain_timeout_msecs;
 extern unsigned int rx_stall_timeout_msecs;
 extern unsigned int xenvif_max_queues;
+extern unsigned int xenvif_hash_cache_size;
 
 #ifdef CONFIG_DEBUG_FS
 extern struct dentry *xen_netback_dbg_root;
@@ -366,4 +398,18 @@ void xenvif_skb_zerocopy_complete(struct xenvif_queue *queue);
 bool xenvif_mcast_match(struct xenvif *vif, const u8 *addr);
 void xenvif_mcast_addr_list_free(struct xenvif *vif);
 
+/* Hash */
+void xenvif_init_hash(struct xenvif *vif);
+void xenvif_deinit_hash(struct xenvif *vif);
+
+u32 xenvif_set_hash_alg(struct xenvif *vif, u32 alg);
+u32 xenvif_get_hash_flags(struct xenvif *vif, u32 *flags);
+u32 xenvif_set_hash_flags(struct xenvif *vif, u32 flags);
+u32 xenvif_set_hash_key(struct xenvif *vif, u32 gref, u32 len);
+u32 xenvif_set_hash_mapping_size(struct xenvif *vif, u32 size);
+u32 xenvif_set_hash_mapping(struct xenvif *vif, u32 gref, u32 len,
+			    u32 off);
+
+void xenvif_set_skb_hash(struct xenvif *vif, struct sk_buff *skb);
+
 #endif /* __XEN_NETBACK__COMMON_H__ */

drivers/net/xen-netback/hash.c

+/*
+ * Copyright (c) 2016 Citrix Systems Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Softare Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#define XEN_NETIF_DEFINE_TOEPLITZ
+
+#include "common.h"
+#include <linux/vmalloc.h>
+#include <linux/rculist.h>
+
+static void xenvif_del_hash(struct rcu_head *rcu)
+{
+	struct xenvif_hash_cache_entry *entry;
+
+	entry = container_of(rcu, struct xenvif_hash_cache_entry, rcu);
+
+	kfree(entry);
+}
+
+static void xenvif_add_hash(struct xenvif *vif, const u8 *tag,
+			    unsigned int len, u32 val)
+{
+	struct xenvif_hash_cache_entry *new, *entry, *oldest;
+	unsigned long flags;
+	bool found;
+
+	new = kmalloc(sizeof(*entry), GFP_KERNEL);
+	if (!new)
+		return;
+
+	memcpy(new->tag, tag, len);
+	new->len = len;
+	new->val = val;
+
+	spin_lock_irqsave(&vif->hash.cache.lock, flags);
+
+	found = false;
+	oldest = NULL;
+	list_for_each_entry_rcu(entry, &vif->hash.cache.list, link) {
+		/* Make sure we don't add duplicate entries */
+		if (entry->len == len &&
+		    memcmp(entry->tag, tag, len) == 0)
+			found = true;
+		if (!oldest || entry->seq < oldest->seq)
+			oldest = entry;
+	}
+
+	if (!found) {
+		new->seq = atomic_inc_return(&vif->hash.cache.seq);
+		list_add_rcu(&new->link, &vif->hash.cache.list);
+
+		if (++vif->hash.cache.count > xenvif_hash_cache_size) {
+			list_del_rcu(&oldest->link);
+			vif->hash.cache.count--;
+			call_rcu(&oldest->rcu, xenvif_del_hash);
+		}
+	}
+
+	spin_unlock_irqrestore(&vif->hash.cache.lock, flags);
+
+	if (found)
+		kfree(new);
+}
+
+static u32 xenvif_new_hash(struct xenvif *vif, const u8 *data,
+			   unsigned int len)
+{
+	u32 val;
+
+	val = xen_netif_toeplitz_hash(vif->hash.key,
+				      sizeof(vif->hash.key),
+				      data, len);
+
+	if (xenvif_hash_cache_size != 0)
+		xenvif_add_hash(vif, data, len, val);
+
+	return val;
+}
+
+static void xenvif_flush_hash(struct xenvif *vif)
+{
+	struct xenvif_hash_cache_entry *entry;
+	unsigned long flags;
+
+	if (xenvif_hash_cache_size == 0)
+		return;
+
+	spin_lock_irqsave(&vif->hash.cache.lock, flags);
+
+	list_for_each_entry_rcu(entry, &vif->hash.cache.list, link) {
+		list_del_rcu(&entry->link);
+		vif->hash.cache.count--;
+		call_rcu(&entry->rcu, xenvif_del_hash);
+	}
+
+	spin_unlock_irqrestore(&vif->hash.cache.lock, flags);
+}
+
+static u32 xenvif_find_hash(struct xenvif *vif, const u8 *data,
+			    unsigned int len)
+{
+	struct xenvif_hash_cache_entry *entry;
+	u32 val;
+	bool found;
+
+	if (len >= XEN_NETBK_HASH_TAG_SIZE)
+		return 0;
+
+	if (xenvif_hash_cache_size == 0)
+		return xenvif_new_hash(vif, data, len);
+
+	rcu_read_lock();
+
+	found = false;
+
+	list_for_each_entry_rcu(entry, &vif->hash.cache.list, link) {
+		if (entry->len == len &&
+		    memcmp(entry->tag, data, len) == 0) {
+			val = entry->val;
+			entry->seq = atomic_inc_return(&vif->hash.cache.seq);
+			found = true;
+			break;
+		}
+	}
+
+	rcu_read_unlock();
+
+	if (!found)
+		val = xenvif_new_hash(vif, data, len);
+
+	return val;
+}
+
+void xenvif_set_skb_hash(struct xenvif *vif, struct sk_buff *skb)
+{
+	struct flow_keys flow;
+	u32 hash = 0;
+	enum pkt_hash_types type = PKT_HASH_TYPE_NONE;
+	u32 flags = vif->hash.flags;
+	bool has_tcp_hdr;
+
+	/* Quick rejection test: If the network protocol doesn't
+	 * correspond to any enabled hash type then there's no point
+	 * in parsing the packet header.
+	 */
+	switch (skb->protocol) {
+	case htons(ETH_P_IP):
+		if (flags & (XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP |
+			     XEN_NETIF_CTRL_HASH_TYPE_IPV4))
+			break;
+
+		goto done;
+
+	case htons(ETH_P_IPV6):
+		if (flags & (XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP |
+			     XEN_NETIF_CTRL_HASH_TYPE_IPV6))
+			break;
+
+		goto done;
+
+	default:
+		goto done;
+	}
+
+	memset(&flow, 0, sizeof(flow));
+	if (!skb_flow_dissect_flow_keys(skb, &flow, 0))
+		goto done;
+
+	has_tcp_hdr = (flow.basic.ip_proto == IPPROTO_TCP) &&
+		      !(flow.control.flags & FLOW_DIS_IS_FRAGMENT);
+
+	switch (skb->protocol) {
+	case htons(ETH_P_IP):
+		if (has_tcp_hdr &&
+		    (flags & XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP)) {
+			u8 data[12];
+
+			memcpy(&data[0], &flow.addrs.v4addrs.src, 4);
+			memcpy(&data[4], &flow.addrs.v4addrs.dst, 4);
+			memcpy(&data[8], &flow.ports.src, 2);
+			memcpy(&data[10], &flow.ports.dst, 2);
+
+			hash = xenvif_find_hash(vif, data, sizeof(data));
+			type = PKT_HASH_TYPE_L4;
+		} else if (flags & XEN_NETIF_CTRL_HASH_TYPE_IPV4) {
+			u8 data[8];
+
+			memcpy(&data[0], &flow.addrs.v4addrs.src, 4);
+			memcpy(&data[4], &flow.addrs.v4addrs.dst, 4);
+
+			hash = xenvif_find_hash(vif, data, sizeof(data));
+			type = PKT_HASH_TYPE_L3;
+		}
+
+		break;
+
+	case htons(ETH_P_IPV6):
+		if (has_tcp_hdr &&
+		    (flags & XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP)) {
+			u8 data[36];
+
+			memcpy(&data[0], &flow.addrs.v6addrs.src, 16);
+			memcpy(&data[16], &flow.addrs.v6addrs.dst, 16);
+			memcpy(&data[32], &flow.ports.src, 2);
+			memcpy(&data[34], &flow.ports.dst, 2);
+
+			hash = xenvif_find_hash(vif, data, sizeof(data));
+			type = PKT_HASH_TYPE_L4;
+		} else if (flags & XEN_NETIF_CTRL_HASH_TYPE_IPV6) {
+			u8 data[32];
+
+			memcpy(&data[0], &flow.addrs.v6addrs.src, 16);
+			memcpy(&data[16], &flow.addrs.v6addrs.dst, 16);
+
+			hash = xenvif_find_hash(vif, data, sizeof(data));
+			type = PKT_HASH_TYPE_L3;
+		}
+
+		break;
+	}
+
+done:
+	if (type == PKT_HASH_TYPE_NONE)
+		skb_clear_hash(skb);
+	else
+		__skb_set_sw_hash(skb, hash, type == PKT_HASH_TYPE_L4);
+}
+
+u32 xenvif_set_hash_alg(struct xenvif *vif, u32 alg)
+{
+	switch (alg) {
+	case XEN_NETIF_CTRL_HASH_ALGORITHM_NONE:
+	case XEN_NETIF_CTRL_HASH_ALGORITHM_TOEPLITZ:
+		break;
+
+	default:
+		return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
+	}
+
+	vif->hash.alg = alg;
+
+	return XEN_NETIF_CTRL_STATUS_SUCCESS;
+}
+
+u32 xenvif_get_hash_flags(struct xenvif *vif, u32 *flags)
+{
+	if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE)
+		return XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED;
+
+	*flags = XEN_NETIF_CTRL_HASH_TYPE_IPV4 |
+		 XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP |
+		 XEN_NETIF_CTRL_HASH_TYPE_IPV6 |
+		 XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP;
+
+	return XEN_NETIF_CTRL_STATUS_SUCCESS;
+}
+
+u32 xenvif_set_hash_flags(struct xenvif *vif, u32 flags)
+{
+	if (flags & ~(XEN_NETIF_CTRL_HASH_TYPE_IPV4 |
+		      XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP |
+		      XEN_NETIF_CTRL_HASH_TYPE_IPV6 |
+		      XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP))
+		return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
+
+	if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE)
+		return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
+
+	vif->hash.flags = flags;
+
+	return XEN_NETIF_CTRL_STATUS_SUCCESS;
+}
+
+u32 xenvif_set_hash_key(struct xenvif *vif, u32 gref, u32 len)
+{
+	u8 *key = vif->hash.key;
+	struct gnttab_copy copy_op = {
+		.source.u.ref = gref,
+		.source.domid = vif->domid,
+		.dest.u.gmfn = virt_to_gfn(key),
+		.dest.domid = DOMID_SELF,
+		.dest.offset = xen_offset_in_page(key),
+		.len = len,
+		.flags = GNTCOPY_source_gref
+	};
+
+	if (len > XEN_NETBK_MAX_HASH_KEY_SIZE)
+		return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
+
+	if (len != 0) {
+		gnttab_batch_copy(&copy_op, 1);
+
+		if (copy_op.status != GNTST_okay)
+			return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
+	}
+
+	/* Clear any remaining key octets */
+	if (len < XEN_NETBK_MAX_HASH_KEY_SIZE)
+		memset(key + len, 0, XEN_NETBK_MAX_HASH_KEY_SIZE - len);
+
+	xenvif_flush_hash(vif);
+
+	return XEN_NETIF_CTRL_STATUS_SUCCESS;
+}
+
+u32 xenvif_set_hash_mapping_size(struct xenvif *vif, u32 size)
+{
+	if (size > XEN_NETBK_MAX_HASH_MAPPING_SIZE)
+		return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
+
+	vif->hash.size = size;
+	memset(vif->hash.mapping, 0, sizeof(u32) * size);
+
+	return XEN_NETIF_CTRL_STATUS_SUCCESS;
+}
+
+u32 xenvif_set_hash_mapping(struct xenvif *vif, u32 gref, u32 len,
+			    u32 off)
+{
+	u32 *mapping = &vif->hash.mapping[off];
+	struct gnttab_copy copy_op = {
+		.source.u.ref = gref,
+		.source.domid = vif->domid,
+		.dest.u.gmfn = virt_to_gfn(mapping),
+		.dest.domid = DOMID_SELF,
+		.dest.offset = xen_offset_in_page(mapping),
+		.len = len * sizeof(u32),
+		.flags = GNTCOPY_source_gref
+	};
+
+	if ((off + len > vif->hash.size) || copy_op.len > XEN_PAGE_SIZE)
+		return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
+
+	while (len-- != 0)
+		if (mapping[off++] >= vif->num_queues)
+			return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
+
+	if (len != 0) {
+		gnttab_batch_copy(&copy_op, 1);
+
+		if (copy_op.status != GNTST_okay)
+			return XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER;
+	}
+
+	return XEN_NETIF_CTRL_STATUS_SUCCESS;
+}
+
+void xenvif_init_hash(struct xenvif *vif)
+{
+	if (xenvif_hash_cache_size == 0)
+		return;
+
+	spin_lock_init(&vif->hash.cache.lock);
+	INIT_LIST_HEAD(&vif->hash.cache.list);
+}
+
+void xenvif_deinit_hash(struct xenvif *vif)
+{
+	xenvif_flush_hash(vif);
+}

drivers/net/xen-netback/interface.c

@@ -151,6 +151,24 @@ void xenvif_wake_queue(struct xenvif_queue *queue)
 	netif_tx_wake_queue(netdev_get_tx_queue(dev, id));
 }
 
+static u16 xenvif_select_queue(struct net_device *dev, struct sk_buff *skb,
+			       void *accel_priv,
+			       select_queue_fallback_t fallback)
+{
+	struct xenvif *vif = netdev_priv(dev);
+	unsigned int size = vif->hash.size;
+
+	if (vif->hash.alg == XEN_NETIF_CTRL_HASH_ALGORITHM_NONE)
+		return fallback(dev, skb) % dev->real_num_tx_queues;
+
+	xenvif_set_skb_hash(vif, skb);
+
+	if (size == 0)
+		return skb_get_hash_raw(skb) % dev->real_num_tx_queues;
+
+	return vif->hash.mapping[skb_get_hash_raw(skb) % size];
+}
+
 static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct xenvif *vif = netdev_priv(dev);
@@ -395,6 +413,7 @@ static const struct ethtool_ops xenvif_ethtool_ops = {
 };
 
 static const struct net_device_ops xenvif_netdev_ops = {
+	.ndo_select_queue = xenvif_select_queue,
 	.ndo_start_xmit	= xenvif_start_xmit,
 	.ndo_get_stats	= xenvif_get_stats,
 	.ndo_open	= xenvif_open,
@@ -563,6 +582,8 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref,
 
 	vif->ctrl_irq = err;
 
+	xenvif_init_hash(vif);
+
 	task = kthread_create(xenvif_ctrl_kthread, (void *)vif,
 			      "%s-control", dev->name);
 	if (IS_ERR(task)) {
@@ -579,6 +600,7 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref,
 	return 0;
 
 err_deinit:
+	xenvif_deinit_hash(vif);
 	unbind_from_irqhandler(vif->ctrl_irq, vif);
 	vif->ctrl_irq = 0;
 
@@ -749,6 +771,8 @@ void xenvif_disconnect_ctrl(struct xenvif *vif)
 		vif->ctrl_task = NULL;
 	}
 
+	xenvif_deinit_hash(vif);
+
 	if (vif->ctrl_irq) {
 		unbind_from_irqhandler(vif->ctrl_irq, vif);
 		vif->ctrl_irq = 0;

drivers/net/xen-netback/netback.c

@@ -89,6 +89,11 @@ module_param(fatal_skb_slots, uint, 0444);
  */
 #define XEN_NETBACK_TX_COPY_LEN 128
 
+/* This is the maximum number of flows in the hash cache. */
+#define XENVIF_HASH_CACHE_SIZE_DEFAULT 64
+unsigned int xenvif_hash_cache_size = XENVIF_HASH_CACHE_SIZE_DEFAULT;
+module_param_named(hash_cache_size, xenvif_hash_cache_size, uint, 0644);
+MODULE_PARM_DESC(hash_cache_size, "Number of flows in the hash cache");
 
 static void xenvif_idx_release(struct xenvif_queue *queue, u16 pending_idx,
 			       u8 status);
@@ -2192,8 +2197,48 @@ static void push_ctrl_response(struct xenvif *vif)
 static void process_ctrl_request(struct xenvif *vif,
 				 const struct xen_netif_ctrl_request *req)
 {
-	make_ctrl_response(vif, req, XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED,
-			   0);
+	u32 status = XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED;
+	u32 data = 0;
+
+	switch (req->type) {
+	case XEN_NETIF_CTRL_TYPE_SET_HASH_ALGORITHM:
+		status = xenvif_set_hash_alg(vif, req->data[0]);
+		break;
+
+	case XEN_NETIF_CTRL_TYPE_GET_HASH_FLAGS:
+		status = xenvif_get_hash_flags(vif, &data);
+		break;
+
+	case XEN_NETIF_CTRL_TYPE_SET_HASH_FLAGS:
+		status = xenvif_set_hash_flags(vif, req->data[0]);
+		break;
+
+	case XEN_NETIF_CTRL_TYPE_SET_HASH_KEY:
+		status = xenvif_set_hash_key(vif, req->data[0],
+					     req->data[1]);
+		break;
+
+	case XEN_NETIF_CTRL_TYPE_GET_HASH_MAPPING_SIZE:
+		status = XEN_NETIF_CTRL_STATUS_SUCCESS;
+		data = XEN_NETBK_MAX_HASH_MAPPING_SIZE;
+		break;
+
+	case XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING_SIZE:
+		status = xenvif_set_hash_mapping_size(vif,
+						      req->data[0]);
+		break;
+
+	case XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING:
+		status = xenvif_set_hash_mapping(vif, req->data[0],
+						 req->data[1],
+						 req->data[2]);
+		break;
+
+	default:
+		break;
+	}
+
+	make_ctrl_response(vif, req, status, data);
 	push_ctrl_response(vif);
 }