> -----Original Message-----
> From: Chuck Lever <cel@xxxxxxxxxx>
> Sent: Saturday, 3 June 2023 15:56
> To: Bernard Metzler <BMT@xxxxxxxxxxxxxx>
> Cc: Tom Talpey <tom@xxxxxxxxxx>; Chuck Lever <chuck.lever@xxxxxxxxxx>;
> linux-rdma@xxxxxxxxxxxxxxx; tom@xxxxxxxxxx
> Subject: [EXTERNAL] [PATCH RFC] RDMA/siw: Fabricate a GID on tun and
> loopback devices
>
> From: Chuck Lever <chuck.lever@xxxxxxxxxx>
>
> LOOPBACK and NONE (tunnel) devices have all-zero MAC addresses.
> Currently, siw_device_create() falls back to copying the IB device's
> name in those cases, because an all-zero MAC address breaks the RDMA
> core address resolution mechanism.
>
> However, at the point when siw_device_create() constructs a GID, the
> ib_device::name field is uninitialized, leaving the MAC address to
> remain in an all-zero state.
>
> Fabricate a random artificial GID for such devices, and ensure that
> artificial GID is returned for all device query operations.
>
> Reported-by: Tom Talpey <tom@xxxxxxxxxx>
> Fixes: a2d36b02c15d ("RDMA/siw: Enable siw on tunnel devices")
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> ---
> drivers/infiniband/sw/siw/siw.h | 1 +
> drivers/infiniband/sw/siw/siw_main.c | 26 +++++++++++---------------
> drivers/infiniband/sw/siw/siw_verbs.c | 4 ++--
> 3 files changed, 14 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/infiniband/sw/siw/siw.h
> b/drivers/infiniband/sw/siw/siw.h
> index d7f5b2a8669d..41fb8976abc6 100644
> --- a/drivers/infiniband/sw/siw/siw.h
> +++ b/drivers/infiniband/sw/siw/siw.h
> @@ -74,6 +74,7 @@ struct siw_device {
>
> u32 vendor_part_id;
> int numa_node;
> + char raw_gid[ETH_ALEN];
>
> /* physical port state (only one port per device) */
> enum ib_port_state state;
> diff --git a/drivers/infiniband/sw/siw/siw_main.c
> b/drivers/infiniband/sw/siw/siw_main.c
> index 1225ca613f50..efc86565ac5d 100644
> --- a/drivers/infiniband/sw/siw/siw_main.c
> +++ b/drivers/infiniband/sw/siw/siw_main.c
> @@ -75,8 +75,7 @@ static int siw_device_register(struct siw_device *sdev,
> const char *name)
> return rv;
> }
>
> - siw_dbg(base_dev, "HWaddr=%pM\n", sdev->netdev->dev_addr);
> -
> + siw_dbg(base_dev, "HWaddr=%pM\n", sdev->raw_gid);
> return 0;
> }
>
> @@ -314,24 +313,21 @@ static struct siw_device *siw_device_create(struct
> net_device *netdev)
> return NULL;
>
> base_dev = &sdev->base_dev;
> -
> sdev->netdev = netdev;
>
> - if (netdev->type != ARPHRD_LOOPBACK && netdev->type != ARPHRD_NONE) {
> - addrconf_addr_eui48((unsigned char *)&base_dev->node_guid,
> - netdev->dev_addr);
> - } else {
> + switch (netdev->type) {
> + case ARPHRD_LOOPBACK:
> + case ARPHRD_NONE:
> /*
> - * This device does not have a HW address,
> - * but connection mangagement lib expects gid != 0
> + * This device does not have a HW address, but
> + * connection mangagement requires a unique gid.
> */
> - size_t len = min_t(size_t, strlen(base_dev->name), 6);
> - char addr[6] = { };
> -
> - memcpy(addr, base_dev->name, len);
> - addrconf_addr_eui48((unsigned char *)&base_dev->node_guid,
> - addr);
> + eth_random_addr(sdev->raw_gid);
> + break;
> + default:
> + memcpy(sdev->raw_gid, netdev->dev_addr, ETH_ALEN);
> }
> + addrconf_addr_eui48((u8 *)&base_dev->node_guid, sdev->raw_gid);
>
> base_dev->uverbs_cmd_mask |= BIT_ULL(IB_USER_VERBS_CMD_POST_SEND);
>
> diff --git a/drivers/infiniband/sw/siw/siw_verbs.c
> b/drivers/infiniband/sw/siw/siw_verbs.c
> index 398ec13db624..32b0befd25e2 100644
> --- a/drivers/infiniband/sw/siw/siw_verbs.c
> +++ b/drivers/infiniband/sw/siw/siw_verbs.c
> @@ -157,7 +157,7 @@ int siw_query_device(struct ib_device *base_dev, struct
> ib_device_attr *attr,
> attr->vendor_part_id = sdev->vendor_part_id;
>
> addrconf_addr_eui48((u8 *)&attr->sys_image_guid,
> - sdev->netdev->dev_addr);
> + sdev->raw_gid);
>
> return 0;
> }
> @@ -218,7 +218,7 @@ int siw_query_gid(struct ib_device *base_dev, u32 port,
> int idx,
>
> /* subnet_prefix == interface_id == 0; */
> memset(gid, 0, sizeof(*gid));
> - memcpy(&gid->raw[0], sdev->netdev->dev_addr, 6);
> + memcpy(gid->raw, sdev->raw_gid, ETH_ALEN);
>
> return 0;
> }
>
That looks good to me, thanks!
