Expose c0 and SW encap ICM for RDMA

These two series from Mark and Shun extend RDMA mlx5 API.

Mark's series provides c0 register used to match egress
traffic sent by local device.

Shun's series adds new type for ICM area.

Link: https://lore.kernel.org/all/cover.1701871118.git.leon@kernel.org
Signed-off-by: Leon Romanovsky <leon@kernel.org>

1 files changed, 156 insertions, 21 deletions

diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c
index a1e4239c7d75..72b6af1d2ed3 100644
--- a/io_uring/kbuf.c
+++ b/io_uring/kbuf.c
@@ -33,19 +33,42 @@ struct io_provide_buf {
 	__u16				bid;
 };
 
+struct io_buf_free {
+	struct hlist_node		list;
+	void				*mem;
+	size_t				size;
+	int				inuse;
+};
+
+static struct io_buffer_list *__io_buffer_get_list(struct io_ring_ctx *ctx,
+						   struct io_buffer_list *bl,
+						   unsigned int bgid)
+{
+	if (bl && bgid < BGID_ARRAY)
+		return &bl[bgid];
+
+	return xa_load(&ctx->io_bl_xa, bgid);
+}
+
 static inline struct io_buffer_list *io_buffer_get_list(struct io_ring_ctx *ctx,
 							unsigned int bgid)
 {
-	if (ctx->io_bl && bgid < BGID_ARRAY)
-		return &ctx->io_bl[bgid];
+	lockdep_assert_held(&ctx->uring_lock);
 
-	return xa_load(&ctx->io_bl_xa, bgid);
+	return __io_buffer_get_list(ctx, ctx->io_bl, bgid);
 }
 
 static int io_buffer_add_list(struct io_ring_ctx *ctx,
 			      struct io_buffer_list *bl, unsigned int bgid)
 {
+	/*
+	 * Store buffer group ID and finally mark the list as visible.
+	 * The normal lookup doesn't care about the visibility as we're
+	 * always under the ->uring_lock, but the RCU lookup from mmap does.
+	 */
 	bl->bgid = bgid;
+	smp_store_release(&bl->is_ready, 1);
+
 	if (bgid < BGID_ARRAY)
 		return 0;
 
@@ -196,21 +219,40 @@ void __user *io_buffer_select(struct io_kiocb *req, size_t *len,
 
 static __cold int io_init_bl_list(struct io_ring_ctx *ctx)
 {
+	struct io_buffer_list *bl;
 	int i;
 
-	ctx->io_bl = kcalloc(BGID_ARRAY, sizeof(struct io_buffer_list),
-				GFP_KERNEL);
-	if (!ctx->io_bl)
+	bl = kcalloc(BGID_ARRAY, sizeof(struct io_buffer_list), GFP_KERNEL);
+	if (!bl)
 		return -ENOMEM;
 
 	for (i = 0; i < BGID_ARRAY; i++) {
-		INIT_LIST_HEAD(&ctx->io_bl[i].buf_list);
-		ctx->io_bl[i].bgid = i;
+		INIT_LIST_HEAD(&bl[i].buf_list);
+		bl[i].bgid = i;
 	}
 
+	smp_store_release(&ctx->io_bl, bl);
 	return 0;
 }
 
+/*
+ * Mark the given mapped range as free for reuse
+ */
+static void io_kbuf_mark_free(struct io_ring_ctx *ctx, struct io_buffer_list *bl)
+{
+	struct io_buf_free *ibf;
+
+	hlist_for_each_entry(ibf, &ctx->io_buf_list, list) {
+		if (bl->buf_ring == ibf->mem) {
+			ibf->inuse = 0;
+			return;
+		}
+	}
+
+	/* can't happen... */
+	WARN_ON_ONCE(1);
+}
+
 static int __io_remove_buffers(struct io_ring_ctx *ctx,
 			       struct io_buffer_list *bl, unsigned nbufs)
 {
@@ -223,7 +265,11 @@ static int __io_remove_buffers(struct io_ring_ctx *ctx,
 	if (bl->is_mapped) {
 		i = bl->buf_ring->tail - bl->head;
 		if (bl->is_mmap) {
-			folio_put(virt_to_folio(bl->buf_ring));
+			/*
+			 * io_kbuf_list_free() will free the page(s) at
+			 * ->release() time.
+			 */
+			io_kbuf_mark_free(ctx, bl);
 			bl->buf_ring = NULL;
 			bl->is_mmap = 0;
 		} else if (bl->buf_nr_pages) {
@@ -274,9 +320,17 @@ void io_destroy_buffers(struct io_ring_ctx *ctx)
 	xa_for_each(&ctx->io_bl_xa, index, bl) {
 		xa_erase(&ctx->io_bl_xa, bl->bgid);
 		__io_remove_buffers(ctx, bl, -1U);
-		kfree(bl);
+		kfree_rcu(bl, rcu);
 	}
 
+	/*
+	 * Move deferred locked entries to cache before pruning
+	 */
+	spin_lock(&ctx->completion_lock);
+	if (!list_empty(&ctx->io_buffers_comp))
+		list_splice_init(&ctx->io_buffers_comp, &ctx->io_buffers_cache);
+	spin_unlock(&ctx->completion_lock);
+
 	list_for_each_safe(item, tmp, &ctx->io_buffers_cache) {
 		buf = list_entry(item, struct io_buffer, list);
 		kmem_cache_free(io_buf_cachep, buf);
@@ -460,7 +514,16 @@ int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags)
 		INIT_LIST_HEAD(&bl->buf_list);
 		ret = io_buffer_add_list(ctx, bl, p->bgid);
 		if (ret) {
-			kfree(bl);
+			/*
+			 * Doesn't need rcu free as it was never visible, but
+			 * let's keep it consistent throughout. Also can't
+			 * be a lower indexed array group, as adding one
+			 * where lookup failed cannot happen.
+			 */
+			if (p->bgid >= BGID_ARRAY)
+				kfree_rcu(bl, rcu);
+			else
+				WARN_ON_ONCE(1);
 			goto err;
 		}
 	}
@@ -531,19 +594,63 @@ error_unpin:
 	return -EINVAL;
 }
 
-static int io_alloc_pbuf_ring(struct io_uring_buf_reg *reg,
+/*
+ * See if we have a suitable region that we can reuse, rather than allocate
+ * both a new io_buf_free and mem region again. We leave it on the list as
+ * even a reused entry will need freeing at ring release.
+ */
+static struct io_buf_free *io_lookup_buf_free_entry(struct io_ring_ctx *ctx,
+						    size_t ring_size)
+{
+	struct io_buf_free *ibf, *best = NULL;
+	size_t best_dist;
+
+	hlist_for_each_entry(ibf, &ctx->io_buf_list, list) {
+		size_t dist;
+
+		if (ibf->inuse || ibf->size < ring_size)
+			continue;
+		dist = ibf->size - ring_size;
+		if (!best || dist < best_dist) {
+			best = ibf;
+			if (!dist)
+				break;
+			best_dist = dist;
+		}
+	}
+
+	return best;
+}
+
+static int io_alloc_pbuf_ring(struct io_ring_ctx *ctx,
+			      struct io_uring_buf_reg *reg,
 			      struct io_buffer_list *bl)
 {
-	gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP;
+	struct io_buf_free *ibf;
 	size_t ring_size;
 	void *ptr;
 
 	ring_size = reg->ring_entries * sizeof(struct io_uring_buf_ring);
-	ptr = (void *) __get_free_pages(gfp, get_order(ring_size));
-	if (!ptr)
-		return -ENOMEM;
 
-	bl->buf_ring = ptr;
+	/* Reuse existing entry, if we can */
+	ibf = io_lookup_buf_free_entry(ctx, ring_size);
+	if (!ibf) {
+		ptr = io_mem_alloc(ring_size);
+		if (IS_ERR(ptr))
+			return PTR_ERR(ptr);
+
+		/* Allocate and store deferred free entry */
+		ibf = kmalloc(sizeof(*ibf), GFP_KERNEL_ACCOUNT);
+		if (!ibf) {
+			io_mem_free(ptr);
+			return -ENOMEM;
+		}
+		ibf->mem = ptr;
+		ibf->size = ring_size;
+		hlist_add_head(&ibf->list, &ctx->io_buf_list);
+	}
+	ibf->inuse = 1;
+	bl->buf_ring = ibf->mem;
 	bl->is_mapped = 1;
 	bl->is_mmap = 1;
 	return 0;
@@ -555,6 +662,8 @@ int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
 	struct io_buffer_list *bl, *free_bl = NULL;
 	int ret;
 
+	lockdep_assert_held(&ctx->uring_lock);
+
 	if (copy_from_user(&reg, arg, sizeof(reg)))
 		return -EFAULT;
 
@@ -599,7 +708,7 @@ int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
 	if (!(reg.flags & IOU_PBUF_RING_MMAP))
 		ret = io_pin_pbuf_ring(&reg, bl);
 	else
-		ret = io_alloc_pbuf_ring(&reg, bl);
+		ret = io_alloc_pbuf_ring(ctx, &reg, bl);
 
 	if (!ret) {
 		bl->nr_entries = reg.ring_entries;
@@ -609,7 +718,7 @@ int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
 		return 0;
 	}
 
-	kfree(free_bl);
+	kfree_rcu(free_bl, rcu);
 	return ret;
 }
 
@@ -618,6 +727,8 @@ int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
 	struct io_uring_buf_reg reg;
 	struct io_buffer_list *bl;
 
+	lockdep_assert_held(&ctx->uring_lock);
+
 	if (copy_from_user(&reg, arg, sizeof(reg)))
 		return -EFAULT;
 	if (reg.resv[0] || reg.resv[1] || reg.resv[2])
@@ -634,7 +745,7 @@ int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
 	__io_remove_buffers(ctx, bl, -1U);
 	if (bl->bgid >= BGID_ARRAY) {
 		xa_erase(&ctx->io_bl_xa, bl->bgid);
-		kfree(bl);
+		kfree_rcu(bl, rcu);
 	}
 	return 0;
 }
@@ -643,9 +754,33 @@ void *io_pbuf_get_address(struct io_ring_ctx *ctx, unsigned long bgid)
 {
 	struct io_buffer_list *bl;
 
-	bl = io_buffer_get_list(ctx, bgid);
+	bl = __io_buffer_get_list(ctx, smp_load_acquire(&ctx->io_bl), bgid);
+
 	if (!bl || !bl->is_mmap)
 		return NULL;
+	/*
+	 * Ensure the list is fully setup. Only strictly needed for RCU lookup
+	 * via mmap, and in that case only for the array indexed groups. For
+	 * the xarray lookups, it's either visible and ready, or not at all.
+	 */
+	if (!smp_load_acquire(&bl->is_ready))
+		return NULL;
 
 	return bl->buf_ring;
 }
+
+/*
+ * Called at or after ->release(), free the mmap'ed buffers that we used
+ * for memory mapped provided buffer rings.
+ */
+void io_kbuf_mmap_list_free(struct io_ring_ctx *ctx)
+{
+	struct io_buf_free *ibf;
+	struct hlist_node *tmp;
+
+	hlist_for_each_entry_safe(ibf, tmp, &ctx->io_buf_list, list) {
+		hlist_del(&ibf->list);
+		io_mem_free(ibf->mem);
+		kfree(ibf);
+	}
+}