dibs: Move data path to dibs layer

Use struct dibs_dmb instead of struct smc_dmb and move the corresponding
client tables to dibs_dev. Leave driver specific implementation details
like sba in the device drivers.

Register and unregister dmbs via dibs_dev_ops. A dmb is dedicated to a
single client, but a dibs device can have dmbs for more than one client.

Trigger dibs clients via dibs_client_ops->handle_irq(), when data is
received into a dmb. For dibs_loopback replace scheduling an smcd receive
tasklet with calling dibs_client_ops->handle_irq().

For loopback devices attach_dmb(), detach_dmb() and move_data() need to
access the dmb tables, so move those to dibs_dev_ops in this patch as well.

Remove remaining definitions of smc_loopback as they are no longer
required, now that everything is in dibs_loopback.

Note that struct ism_client and struct ism_dev are still required in smc
until a follow-on patch moves event handling to dibs. (Loopback does not
use events).

Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Link: https://patch.msgid.link/20250918110500.1731261-14-wintera@linux.ibm.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 257 insertions, 0 deletions

diff --git a/drivers/dibs/dibs_loopback.c b/drivers/dibs/dibs_loopback.c
index 6b53e626a6d1..b3fd0f8100d4 100644
--- a/drivers/dibs/dibs_loopback.c
+++ b/drivers/dibs/dibs_loopback.c
@@ -9,12 +9,18 @@
  *
  */
 
+#include <linux/bitops.h>
+#include <linux/device.h>
 #include <linux/dibs.h>
 #include <linux/slab.h>
+#include <linux/spinlock.h>
 #include <linux/types.h>
 
 #include "dibs_loopback.h"
 
+#define DIBS_LO_SUPPORT_NOCOPY	0x1
+#define DIBS_DMA_ADDR_INVALID	(~(dma_addr_t)0)
+
 static const char dibs_lo_dev_name[] = "lo";
 /* global loopback device */
 static struct dibs_lo_dev *lo_dev;
@@ -33,11 +39,259 @@ static int dibs_lo_query_rgid(struct dibs_dev *dibs, const uuid_t *rgid,
 	return 0;
 }
 
+static int dibs_lo_max_dmbs(void)
+{
+	return DIBS_LO_MAX_DMBS;
+}
+
+static int dibs_lo_register_dmb(struct dibs_dev *dibs, struct dibs_dmb *dmb,
+				struct dibs_client *client)
+{
+	struct dibs_lo_dmb_node *dmb_node, *tmp_node;
+	struct dibs_lo_dev *ldev;
+	unsigned long flags;
+	int sba_idx, rc;
+
+	ldev = dibs->drv_priv;
+	sba_idx = dmb->idx;
+	/* check space for new dmb */
+	for_each_clear_bit(sba_idx, ldev->sba_idx_mask, DIBS_LO_MAX_DMBS) {
+		if (!test_and_set_bit(sba_idx, ldev->sba_idx_mask))
+			break;
+	}
+	if (sba_idx == DIBS_LO_MAX_DMBS)
+		return -ENOSPC;
+
+	dmb_node = kzalloc(sizeof(*dmb_node), GFP_KERNEL);
+	if (!dmb_node) {
+		rc = -ENOMEM;
+		goto err_bit;
+	}
+
+	dmb_node->sba_idx = sba_idx;
+	dmb_node->len = dmb->dmb_len;
+	dmb_node->cpu_addr = kzalloc(dmb_node->len, GFP_KERNEL |
+				     __GFP_NOWARN | __GFP_NORETRY |
+				     __GFP_NOMEMALLOC);
+	if (!dmb_node->cpu_addr) {
+		rc = -ENOMEM;
+		goto err_node;
+	}
+	dmb_node->dma_addr = DIBS_DMA_ADDR_INVALID;
+	refcount_set(&dmb_node->refcnt, 1);
+
+again:
+	/* add new dmb into hash table */
+	get_random_bytes(&dmb_node->token, sizeof(dmb_node->token));
+	write_lock_bh(&ldev->dmb_ht_lock);
+	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb_node->token) {
+		if (tmp_node->token == dmb_node->token) {
+			write_unlock_bh(&ldev->dmb_ht_lock);
+			goto again;
+		}
+	}
+	hash_add(ldev->dmb_ht, &dmb_node->list, dmb_node->token);
+	write_unlock_bh(&ldev->dmb_ht_lock);
+	atomic_inc(&ldev->dmb_cnt);
+
+	dmb->idx = dmb_node->sba_idx;
+	dmb->dmb_tok = dmb_node->token;
+	dmb->cpu_addr = dmb_node->cpu_addr;
+	dmb->dma_addr = dmb_node->dma_addr;
+	dmb->dmb_len = dmb_node->len;
+
+	spin_lock_irqsave(&dibs->lock, flags);
+	dibs->dmb_clientid_arr[sba_idx] = client->id;
+	spin_unlock_irqrestore(&dibs->lock, flags);
+
+	return 0;
+
+err_node:
+	kfree(dmb_node);
+err_bit:
+	clear_bit(sba_idx, ldev->sba_idx_mask);
+	return rc;
+}
+
+static void __dibs_lo_unregister_dmb(struct dibs_lo_dev *ldev,
+				     struct dibs_lo_dmb_node *dmb_node)
+{
+	/* remove dmb from hash table */
+	write_lock_bh(&ldev->dmb_ht_lock);
+	hash_del(&dmb_node->list);
+	write_unlock_bh(&ldev->dmb_ht_lock);
+
+	clear_bit(dmb_node->sba_idx, ldev->sba_idx_mask);
+	kfree(dmb_node->cpu_addr);
+	kfree(dmb_node);
+
+	if (atomic_dec_and_test(&ldev->dmb_cnt))
+		wake_up(&ldev->ldev_release);
+}
+
+static int dibs_lo_unregister_dmb(struct dibs_dev *dibs, struct dibs_dmb *dmb)
+{
+	struct dibs_lo_dmb_node *dmb_node = NULL, *tmp_node;
+	struct dibs_lo_dev *ldev;
+	unsigned long flags;
+
+	ldev = dibs->drv_priv;
+
+	/* find dmb from hash table */
+	read_lock_bh(&ldev->dmb_ht_lock);
+	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb->dmb_tok) {
+		if (tmp_node->token == dmb->dmb_tok) {
+			dmb_node = tmp_node;
+			break;
+		}
+	}
+	read_unlock_bh(&ldev->dmb_ht_lock);
+	if (!dmb_node)
+		return -EINVAL;
+
+	if (refcount_dec_and_test(&dmb_node->refcnt)) {
+		spin_lock_irqsave(&dibs->lock, flags);
+		dibs->dmb_clientid_arr[dmb_node->sba_idx] = NO_DIBS_CLIENT;
+		spin_unlock_irqrestore(&dibs->lock, flags);
+
+		__dibs_lo_unregister_dmb(ldev, dmb_node);
+	}
+	return 0;
+}
+
+static int dibs_lo_support_dmb_nocopy(struct dibs_dev *dibs)
+{
+	return DIBS_LO_SUPPORT_NOCOPY;
+}
+
+static int dibs_lo_attach_dmb(struct dibs_dev *dibs, struct dibs_dmb *dmb)
+{
+	struct dibs_lo_dmb_node *dmb_node = NULL, *tmp_node;
+	struct dibs_lo_dev *ldev;
+
+	ldev = dibs->drv_priv;
+
+	/* find dmb_node according to dmb->dmb_tok */
+	read_lock_bh(&ldev->dmb_ht_lock);
+	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb->dmb_tok) {
+		if (tmp_node->token == dmb->dmb_tok) {
+			dmb_node = tmp_node;
+			break;
+		}
+	}
+	if (!dmb_node) {
+		read_unlock_bh(&ldev->dmb_ht_lock);
+		return -EINVAL;
+	}
+	read_unlock_bh(&ldev->dmb_ht_lock);
+
+	if (!refcount_inc_not_zero(&dmb_node->refcnt))
+		/* the dmb is being unregistered, but has
+		 * not been removed from the hash table.
+		 */
+		return -EINVAL;
+
+	/* provide dmb information */
+	dmb->idx = dmb_node->sba_idx;
+	dmb->dmb_tok = dmb_node->token;
+	dmb->cpu_addr = dmb_node->cpu_addr;
+	dmb->dma_addr = dmb_node->dma_addr;
+	dmb->dmb_len = dmb_node->len;
+	return 0;
+}
+
+static int dibs_lo_detach_dmb(struct dibs_dev *dibs, u64 token)
+{
+	struct dibs_lo_dmb_node *dmb_node = NULL, *tmp_node;
+	struct dibs_lo_dev *ldev;
+
+	ldev = dibs->drv_priv;
+
+	/* find dmb_node according to dmb->dmb_tok */
+	read_lock_bh(&ldev->dmb_ht_lock);
+	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, token) {
+		if (tmp_node->token == token) {
+			dmb_node = tmp_node;
+			break;
+		}
+	}
+	if (!dmb_node) {
+		read_unlock_bh(&ldev->dmb_ht_lock);
+		return -EINVAL;
+	}
+	read_unlock_bh(&ldev->dmb_ht_lock);
+
+	if (refcount_dec_and_test(&dmb_node->refcnt))
+		__dibs_lo_unregister_dmb(ldev, dmb_node);
+	return 0;
+}
+
+static int dibs_lo_move_data(struct dibs_dev *dibs, u64 dmb_tok,
+			     unsigned int idx, bool sf, unsigned int offset,
+			     void *data, unsigned int size)
+{
+	struct dibs_lo_dmb_node *rmb_node = NULL, *tmp_node;
+	struct dibs_lo_dev *ldev;
+	u16 s_mask;
+	u8 client_id;
+	u32 sba_idx;
+
+	ldev = dibs->drv_priv;
+
+	read_lock_bh(&ldev->dmb_ht_lock);
+	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb_tok) {
+		if (tmp_node->token == dmb_tok) {
+			rmb_node = tmp_node;
+			break;
+		}
+	}
+	if (!rmb_node) {
+		read_unlock_bh(&ldev->dmb_ht_lock);
+		return -EINVAL;
+	}
+	memcpy((char *)rmb_node->cpu_addr + offset, data, size);
+	sba_idx = rmb_node->sba_idx;
+	read_unlock_bh(&ldev->dmb_ht_lock);
+
+	if (!sf)
+		return 0;
+
+	spin_lock(&dibs->lock);
+	client_id = dibs->dmb_clientid_arr[sba_idx];
+	s_mask = ror16(0x1000, idx);
+	if (likely(client_id != NO_DIBS_CLIENT && dibs->subs[client_id]))
+		dibs->subs[client_id]->ops->handle_irq(dibs, sba_idx, s_mask);
+	spin_unlock(&dibs->lock);
+
+	return 0;
+}
+
 static const struct dibs_dev_ops dibs_lo_ops = {
 	.get_fabric_id = dibs_lo_get_fabric_id,
 	.query_remote_gid = dibs_lo_query_rgid,
+	.max_dmbs = dibs_lo_max_dmbs,
+	.register_dmb = dibs_lo_register_dmb,
+	.unregister_dmb = dibs_lo_unregister_dmb,
+	.move_data = dibs_lo_move_data,
+	.support_mmapped_rdmb = dibs_lo_support_dmb_nocopy,
+	.attach_dmb = dibs_lo_attach_dmb,
+	.detach_dmb = dibs_lo_detach_dmb,
 };
 
+static void dibs_lo_dev_init(struct dibs_lo_dev *ldev)
+{
+	rwlock_init(&ldev->dmb_ht_lock);
+	hash_init(ldev->dmb_ht);
+	atomic_set(&ldev->dmb_cnt, 0);
+	init_waitqueue_head(&ldev->ldev_release);
+}
+
+static void dibs_lo_dev_exit(struct dibs_lo_dev *ldev)
+{
+	if (atomic_read(&ldev->dmb_cnt))
+		wait_event(ldev->ldev_release, !atomic_read(&ldev->dmb_cnt));
+}
+
 static int dibs_lo_dev_probe(void)
 {
 	struct dibs_lo_dev *ldev;
@@ -56,6 +310,7 @@ static int dibs_lo_dev_probe(void)
 
 	ldev->dibs = dibs;
 	dibs->drv_priv = ldev;
+	dibs_lo_dev_init(ldev);
 	uuid_gen(&dibs->gid);
 	dibs->ops = &dibs_lo_ops;
 
@@ -69,6 +324,7 @@ static int dibs_lo_dev_probe(void)
 	return 0;
 
 err_reg:
+	kfree(dibs->dmb_clientid_arr);
 	/* pairs with dibs_dev_alloc() */
 	put_device(&dibs->dev);
 	kfree(ldev);
@@ -82,6 +338,7 @@ static void dibs_lo_dev_remove(void)
 		return;
 
 	dibs_dev_del(lo_dev->dibs);
+	dibs_lo_dev_exit(lo_dev);
 	/* pairs with dibs_dev_alloc() */
 	put_device(&lo_dev->dibs->dev);
 	kfree(lo_dev);