dibs: Local gid for dibs devices

Define a uuid_t GID attribute to identify a dibs device.

SMC uses 64 Bit and 128 Bit Global Identifiers (GIDs) per device, that
need to be sent via the SMC protocol. Because the smc code uses integers,
network endianness and host endianness need to be considered. Avoid this
in the dibs layer by using uuid_t byte arrays. Future patches could change
SMC to use uuid_t. For now conversion helper functions are introduced.

ISM devices provide 64 Bit GIDs. Map them to dibs uuid_t GIDs like this:
 _________________________________________
| 64 Bit ISM-vPCI GID | 00000000_00000000 |
 -----------------------------------------
If interpreted as UUID [1], this would be interpreted as the UIID variant,
that is reserved for NCS backward compatibility. So it will not collide
with UUIDs that were generated according to the standard.

smc_loopback already uses version 4 UUIDs as 128 Bit GIDs, move that to
dibs loopback. A temporary change to smc_lo_query_rgid() is required,
that will be moved to dibs_loopback with a follow-on patch.

Provide gid of a dibs device as sysfs read-only attribute.

Link: https://datatracker.ietf.org/doc/html/rfc4122 [1]
Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Reviewed-by: Julian Ruess <julianr@linux.ibm.com>
Reviewed-by: Mahanta Jambigi <mjambigi@linux.ibm.com>
Link: https://patch.msgid.link/20250918110500.1731261-11-wintera@linux.ibm.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 4 insertions, 25 deletions

diff --git a/net/smc/smc_loopback.c b/net/smc/smc_loopback.c
index 262d0d0df4d0..454d9d6a6e8f 100644
--- a/net/smc/smc_loopback.c
+++ b/net/smc/smc_loopback.c
@@ -13,6 +13,7 @@
 
 #include <linux/device.h>
 #include <linux/types.h>
+#include <linux/dibs.h>
 #include <net/smc.h>
 
 #include "smc_cdc.h"
@@ -25,25 +26,14 @@
 
 static struct smc_lo_dev *lo_dev;
 
-static void smc_lo_generate_ids(struct smc_lo_dev *ldev)
-{
-	struct smcd_gid *lgid = &ldev->local_gid;
-	uuid_t uuid;
-
-	uuid_gen(&uuid);
-	memcpy(&lgid->gid, &uuid, sizeof(lgid->gid));
-	memcpy(&lgid->gid_ext, (u8 *)&uuid + sizeof(lgid->gid),
-	       sizeof(lgid->gid_ext));
-}
-
 static int smc_lo_query_rgid(struct smcd_dev *smcd, struct smcd_gid *rgid,
 			     u32 vid_valid, u32 vid)
 {
-	struct smc_lo_dev *ldev = smcd->priv;
+	uuid_t temp;
 
+	copy_to_dibsgid(&temp, rgid);
 	/* rgid should be the same as lgid */
-	if (!ldev || rgid->gid != ldev->local_gid.gid ||
-	    rgid->gid_ext != ldev->local_gid.gid_ext)
+	if (!uuid_equal(&temp, &smcd->dibs->gid))
 		return -ENETUNREACH;
 	return 0;
 }
@@ -245,15 +235,6 @@ static int smc_lo_move_data(struct smcd_dev *smcd, u64 dmb_tok,
 	return 0;
 }
 
-static void smc_lo_get_local_gid(struct smcd_dev *smcd,
-				 struct smcd_gid *smcd_gid)
-{
-	struct smc_lo_dev *ldev = smcd->priv;
-
-	smcd_gid->gid = ldev->local_gid.gid;
-	smcd_gid->gid_ext = ldev->local_gid.gid_ext;
-}
-
 static const struct smcd_ops lo_ops = {
 	.query_remote_gid = smc_lo_query_rgid,
 	.register_dmb = smc_lo_register_dmb,
@@ -267,7 +248,6 @@ static const struct smcd_ops lo_ops = {
 	.reset_vlan_required	= NULL,
 	.signal_event		= NULL,
 	.move_data = smc_lo_move_data,
-	.get_local_gid = smc_lo_get_local_gid,
 };
 
 const struct smcd_ops *smc_lo_get_smcd_ops(void)
@@ -277,7 +257,6 @@ const struct smcd_ops *smc_lo_get_smcd_ops(void)
 
 static void smc_lo_dev_init(struct smc_lo_dev *ldev)
 {
-	smc_lo_generate_ids(ldev);
 	rwlock_init(&ldev->dmb_ht_lock);
 	hash_init(ldev->dmb_ht);
 	atomic_set(&ldev->dmb_cnt, 0);