Re: [PATCH] RDMA/srpt: Filter out AGN bits

Hal Rosenstock
2019-08-19T13:49:10Z

On 8/19/2019 9:46 AM, Jason Gunthorpe wrote:
> On Mon, Aug 19, 2019 at 09:40:24AM -0400, Hal Rosenstock wrote:
>> On 8/19/2019 8:21 AM, Jason Gunthorpe wrote:
>>> On Wed, Aug 14, 2019 at 08:15:07AM -0700, Bart Van Assche wrote:
>>>> The ib_srpt driver derives its default service GUID from the node GUID
>>>> of the first encountered HCA. Since that service GUID is passed to
>>>> ib_cm_listen(), the AGN bits must not be set. Since the AGN bits can
>>>> be set in the node GUID of RoCE HCAs, filter these bits out. This
>>>> patch avoids that loading the ib_srpt driver fails as follows for the
>>>> hns driver:
>
> What is the actual problem anyhow? Is some roce GUID using the local
> bits and overlapping with the IB_CM_ASSIGN_SERVICE_ID?
>
> Ie generated VF MAC or something?
>
>>>> ib_srpt srpt_add_one(hns_0) failed.
>>>>
>>>> Cc: oulijun <oulijun@huawei.com>
>>>> Reported-by: oulijun <oulijun@huawei.com>
>>>> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
>>>> drivers/infiniband/ulp/srpt/ib_srpt.c | 3 ++-
>>>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.c b/drivers/infiniband/ulp/srpt/ib_srpt.c
>>>> index e25c70a56be6..114bf8d6c82b 100644
>>>> +++ b/drivers/infiniband/ulp/srpt/ib_srpt.c
>>>> @@ -3109,7 +3109,8 @@ static void srpt_add_one(struct ib_device *device)
>>>> srpt_use_srq(sdev, sdev->port[0].port_attrib.use_srq);
>>>>
>>>> if (!srpt_service_guid)
>>>> - srpt_service_guid = be64_to_cpu(device->node_guid);
>>>> + srpt_service_guid = be64_to_cpu(device->node_guid) &
>>>> + ~IB_SERVICE_ID_AGN_MASK;
>>>
>>> This seems kind of sketchy, masking bits in the GUID is going to make
>>> it non-unique.. Should we do this only for roce or something?
>>>
>>> Hal, do you have any insight?
>>
>> include/rdma/ib_cm.h:#define IB_SERVICE_ID_AGN_MASK
>> cpu_to_be64(0xFF00000000000000ULL)
>>
>> IB_SERVICE_ID_AGN_MASK masks entire first byte of OUI which seems like
>> too much to me as it contains company related bits.
>>
>> Would it work just masking the first 2 bits (local/global and X bits) ?
>
> Maybe if we see a local GUID it should generate a random global GUID
> instead.

I think the OpenIB OUI could be used for that if you want...

> Jason
>