> On Jun 3, 2023, at 10:01 AM, Bernard Metzler <BMT@xxxxxxxxxxxxxx> wrote:
>
>
>
>> -----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:
One thing I'm wondering is if there are other cases where
there is no L2 address besides ARPHRD_NONE and LOOPBACK.
Should we instead check netdev's addrlen instead of checking
the ARP type?
>> /*
>> - * 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!
--
Chuck Lever
