5 files changed, 241 insertions, 18 deletions

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 0bfe6cf2bf8b..f10904ec2172 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -6370,7 +6370,7 @@ int ixgbe_setup_rx_resources(struct ixgbe_adapter *adapter,
 	struct device *dev = rx_ring->dev;
 	int orig_node = dev_to_node(dev);
 	int ring_node = -1;
-	int size;
+	int size, err;
 
 	size = sizeof(struct ixgbe_rx_buffer) * rx_ring->count;
 
@@ -6407,6 +6407,13 @@ int ixgbe_setup_rx_resources(struct ixgbe_adapter *adapter,
 			     rx_ring->queue_index) < 0)
 		goto err;
 
+	err = xdp_rxq_info_reg_mem_model(&rx_ring->xdp_rxq,
+					 MEM_TYPE_PAGE_SHARED, NULL);
+	if (err) {
+		xdp_rxq_info_unreg(&rx_ring->xdp_rxq);
+		goto err;
+	}
+
 	rx_ring->xdp_prog = adapter->xdp_prog;
 
 	return 0;
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 2c85e5cac2a9..283bde85c455 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -854,6 +854,12 @@ static int tun_attach(struct tun_struct *tun, struct file *file,
 				       tun->dev, tfile->queue_index);
 		if (err < 0)
 			goto out;
+		err = xdp_rxq_info_reg_mem_model(&tfile->xdp_rxq,
+						 MEM_TYPE_PAGE_SHARED, NULL);
+		if (err < 0) {
+			xdp_rxq_info_unreg(&tfile->xdp_rxq);
+			goto out;
+		}
 		err = 0;
 	}
 
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index f50e1ad81ad4..42d338fe9a8d 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1305,6 +1305,13 @@ static int virtnet_open(struct net_device *dev)
 		if (err < 0)
 			return err;
 
+		err = xdp_rxq_info_reg_mem_model(&vi->rq[i].xdp_rxq,
+						 MEM_TYPE_PAGE_SHARED, NULL);
+		if (err < 0) {
+			xdp_rxq_info_unreg(&vi->rq[i].xdp_rxq);
+			return err;
+		}
+
 		virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi);
 		virtnet_napi_tx_enable(vi, vi->sq[i].vq, &vi->sq[i].napi);
 	}
diff --git a/include/net/xdp.h b/include/net/xdp.h
index ea3773f94f65..5f67c62540aa 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -41,6 +41,7 @@ enum xdp_mem_type {
 
 struct xdp_mem_info {
 	u32 type; /* enum xdp_mem_type, but known size type */
+	u32 id;
 };
 
 struct xdp_rxq_info {
@@ -99,18 +100,7 @@ struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp)
 	return xdp_frame;
 }
 
-static inline
-void xdp_return_frame(void *data, struct xdp_mem_info *mem)
-{
-	if (mem->type == MEM_TYPE_PAGE_SHARED)
-		page_frag_free(data);
-
-	if (mem->type == MEM_TYPE_PAGE_ORDER0) {
-		struct page *page = virt_to_page(data); /* Assumes order0 page*/
-
-		put_page(page);
-	}
-}
+void xdp_return_frame(void *data, struct xdp_mem_info *mem);
 
 int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
 		     struct net_device *dev, u32 queue_index);
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 7e6b3545277d..8b2cb79b5de0 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -5,6 +5,9 @@
  */
 #include <linux/types.h>
 #include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/idr.h>
+#include <linux/rhashtable.h>
 
 #include <net/xdp.h>
 
@@ -13,6 +16,99 @@
 #define REG_STATE_UNREGISTERED	0x2
 #define REG_STATE_UNUSED	0x3
 
+static DEFINE_IDA(mem_id_pool);
+static DEFINE_MUTEX(mem_id_lock);
+#define MEM_ID_MAX 0xFFFE
+#define MEM_ID_MIN 1
+static int mem_id_next = MEM_ID_MIN;
+
+static bool mem_id_init; /* false */
+static struct rhashtable *mem_id_ht;
+
+struct xdp_mem_allocator {
+	struct xdp_mem_info mem;
+	void *allocator;
+	struct rhash_head node;
+	struct rcu_head rcu;
+};
+
+static u32 xdp_mem_id_hashfn(const void *data, u32 len, u32 seed)
+{
+	const u32 *k = data;
+	const u32 key = *k;
+
+	BUILD_BUG_ON(FIELD_SIZEOF(struct xdp_mem_allocator, mem.id)
+		     != sizeof(u32));
+
+	/* Use cyclic increasing ID as direct hash key, see rht_bucket_index */
+	return key << RHT_HASH_RESERVED_SPACE;
+}
+
+static int xdp_mem_id_cmp(struct rhashtable_compare_arg *arg,
+			  const void *ptr)
+{
+	const struct xdp_mem_allocator *xa = ptr;
+	u32 mem_id = *(u32 *)arg->key;
+
+	return xa->mem.id != mem_id;
+}
+
+static const struct rhashtable_params mem_id_rht_params = {
+	.nelem_hint = 64,
+	.head_offset = offsetof(struct xdp_mem_allocator, node),
+	.key_offset  = offsetof(struct xdp_mem_allocator, mem.id),
+	.key_len = FIELD_SIZEOF(struct xdp_mem_allocator, mem.id),
+	.max_size = MEM_ID_MAX,
+	.min_size = 8,
+	.automatic_shrinking = true,
+	.hashfn    = xdp_mem_id_hashfn,
+	.obj_cmpfn = xdp_mem_id_cmp,
+};
+
+static void __xdp_mem_allocator_rcu_free(struct rcu_head *rcu)
+{
+	struct xdp_mem_allocator *xa;
+
+	xa = container_of(rcu, struct xdp_mem_allocator, rcu);
+
+	/* Allow this ID to be reused */
+	ida_simple_remove(&mem_id_pool, xa->mem.id);
+
+	/* TODO: Depending on allocator type/pointer free resources */
+
+	/* Poison memory */
+	xa->mem.id = 0xFFFF;
+	xa->mem.type = 0xF0F0;
+	xa->allocator = (void *)0xDEAD9001;
+
+	kfree(xa);
+}
+
+static void __xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)
+{
+	struct xdp_mem_allocator *xa;
+	int id = xdp_rxq->mem.id;
+	int err;
+
+	if (id == 0)
+		return;
+
+	mutex_lock(&mem_id_lock);
+
+	xa = rhashtable_lookup(mem_id_ht, &id, mem_id_rht_params);
+	if (!xa) {
+		mutex_unlock(&mem_id_lock);
+		return;
+	}
+
+	err = rhashtable_remove_fast(mem_id_ht, &xa->node, mem_id_rht_params);
+	WARN_ON(err);
+
+	call_rcu(&xa->rcu, __xdp_mem_allocator_rcu_free);
+
+	mutex_unlock(&mem_id_lock);
+}
+
 void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq)
 {
 	/* Simplify driver cleanup code paths, allow unreg "unused" */
@@ -21,8 +117,14 @@ void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq)
 
 	WARN(!(xdp_rxq->reg_state == REG_STATE_REGISTERED), "Driver BUG");
 
+	__xdp_rxq_info_unreg_mem_model(xdp_rxq);
+
 	xdp_rxq->reg_state = REG_STATE_UNREGISTERED;
 	xdp_rxq->dev = NULL;
+
+	/* Reset mem info to defaults */
+	xdp_rxq->mem.id = 0;
+	xdp_rxq->mem.type = 0;
 }
 EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg);
 
@@ -72,20 +174,131 @@ bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq)
 }
 EXPORT_SYMBOL_GPL(xdp_rxq_info_is_reg);
 
+static int __mem_id_init_hash_table(void)
+{
+	struct rhashtable *rht;
+	int ret;
+
+	if (unlikely(mem_id_init))
+		return 0;
+
+	rht = kzalloc(sizeof(*rht), GFP_KERNEL);
+	if (!rht)
+		return -ENOMEM;
+
+	ret = rhashtable_init(rht, &mem_id_rht_params);
+	if (ret < 0) {
+		kfree(rht);
+		return ret;
+	}
+	mem_id_ht = rht;
+	smp_mb(); /* mutex lock should provide enough pairing */
+	mem_id_init = true;
+
+	return 0;
+}
+
+/* Allocate a cyclic ID that maps to allocator pointer.
+ * See: https://www.kernel.org/doc/html/latest/core-api/idr.html
+ *
+ * Caller must lock mem_id_lock.
+ */
+static int __mem_id_cyclic_get(gfp_t gfp)
+{
+	int retries = 1;
+	int id;
+
+again:
+	id = ida_simple_get(&mem_id_pool, mem_id_next, MEM_ID_MAX, gfp);
+	if (id < 0) {
+		if (id == -ENOSPC) {
+			/* Cyclic allocator, reset next id */
+			if (retries--) {
+				mem_id_next = MEM_ID_MIN;
+				goto again;
+			}
+		}
+		return id; /* errno */
+	}
+	mem_id_next = id + 1;
+
+	return id;
+}
+
 int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
 			       enum xdp_mem_type type, void *allocator)
 {
+	struct xdp_mem_allocator *xdp_alloc;
+	gfp_t gfp = GFP_KERNEL;
+	int id, errno, ret;
+	void *ptr;
+
+	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
+		WARN(1, "Missing register, driver bug");
+		return -EFAULT;
+	}
+
 	if (type >= MEM_TYPE_MAX)
 		return -EINVAL;
 
 	xdp_rxq->mem.type = type;
 
-	if (allocator)
-		return -EOPNOTSUPP;
+	if (!allocator)
+		return 0;
+
+	/* Delay init of rhashtable to save memory if feature isn't used */
+	if (!mem_id_init) {
+		mutex_lock(&mem_id_lock);
+		ret = __mem_id_init_hash_table();
+		mutex_unlock(&mem_id_lock);
+		if (ret < 0) {
+			WARN_ON(1);
+			return ret;
+		}
+	}
+
+	xdp_alloc = kzalloc(sizeof(*xdp_alloc), gfp);
+	if (!xdp_alloc)
+		return -ENOMEM;
+
+	mutex_lock(&mem_id_lock);
+	id = __mem_id_cyclic_get(gfp);
+	if (id < 0) {
+		errno = id;
+		goto err;
+	}
+	xdp_rxq->mem.id = id;
+	xdp_alloc->mem  = xdp_rxq->mem;
+	xdp_alloc->allocator = allocator;
+
+	/* Insert allocator into ID lookup table */
+	ptr = rhashtable_insert_slow(mem_id_ht, &id, &xdp_alloc->node);
+	if (IS_ERR(ptr)) {
+		errno = PTR_ERR(ptr);
+		goto err;
+	}
+
+	mutex_unlock(&mem_id_lock);
 
-	/* TODO: Allocate an ID that maps to allocator pointer
-	 * See: https://www.kernel.org/doc/html/latest/core-api/idr.html
-	 */
 	return 0;
+err:
+	mutex_unlock(&mem_id_lock);
+	kfree(xdp_alloc);
+	return errno;
 }
 EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model);
+
+void xdp_return_frame(void *data, struct xdp_mem_info *mem)
+{
+	if (mem->type == MEM_TYPE_PAGE_SHARED) {
+		page_frag_free(data);
+		return;
+	}
+
+	if (mem->type == MEM_TYPE_PAGE_ORDER0) {
+		struct page *page = virt_to_page(data); /* Assumes order0 page*/
+
+		put_page(page);
+	}
+}
+EXPORT_SYMBOL_GPL(xdp_return_frame);