Re: [Suspected Spam] Re: [PATCH for-rc] RDMA/vmw_pvrdma: Fix the active_speed and phys_state value

[Leon Romanovsky <leon@kernel.org>]

On Mon, Nov 02, 2020 at 02:46:40PM -0400, Jason Gunthorpe wrote:
> On Mon, Nov 02, 2020 at 10:38:19AM -0800, Adit Ranadive wrote:
> > On 11/2/20 10:27 AM, Jason Gunthorpe wrote:
> > > On Mon, Nov 02, 2020 at 10:21:21AM -0800, Adit Ranadive wrote:
> > >> On 11/2/20 10:02 AM, Jason Gunthorpe wrote:
> > >>> On Mon, Nov 02, 2020 at 09:55:25AM -0800, Adit Ranadive wrote:
> > >>>> On 10/29/20 9:16 AM, Adit Ranadive wrote:
> > >>>>> On 10/29/20 4:57 AM, Jason Gunthorpe wrote:
> > >>>>>> On Wed, Oct 28, 2020 at 11:19:45PM +0000, Adit Ranadive wrote:
> > >>>>>>> The PVRDMA device still reports the active_speed in u8.
> > >>>>>>> Lets use the ib_eth_get_speed to report the speed and
> > >>>>>>> width. Unfortunately, phys_state gets stored as msb of
> > >>>>>>> the new u16 active_speed.
> > >>>>>>
> > >>>>>> This explanation is not clear, I have no idea what this is fixing
> > >>>>>
> > >>>>> It seemed more clear to me in my head, I guess :).
> > >>>>>
> > >>>>> After commit 376ceb31ff87 changed the active_speed attribute to
> > >>>>> u16, both the active_speed and phys_state attributes in the
> > >>>>> pvrdma_port_attr struct are getting stored in this u16. As a
> > >>>>> result, these show up as invalid values in ibv_devinfo.
> > >>>>>
> > >>>>> Our device still gives us back a u8 active_speed so both these
> > >>>>> are getting stored in the u16. This fix I proposed simply gets
> > >>>>> the active_speed from the netdev while the phys_state still
> > >>>>> needs to come from the pvrdma device, i.e. the msb the of the
> > >>>>> u16. I also removed some unused functions as a result.
> > >>>>>
> > >>>>> Alternatively, I could change the u8 active_width and u16
> > >>>>> active_speed to reserved now that we're getting the active_speed
> > >>>>> and active_width from the ib_get_eth_speed function.
> > >>>>
> > >>>> Jason, did you have any comments on this or did you want me
> > >>>> to just send v1 with an updated description?
> > >>>
> > >>> I still haven't figured out what this is fixing.
> > >>>
> > >>> Is 'struct pvrdma_port_attr' some kind of ABI? If so why isn't the fix
> > >>> to revert the type?
> > >>
> > >> I can revert it but I thought that it had to a u16 based on the IBTA, no?
> > >> Or does that not apply to device-level stuff?
> > >
> > > You didn't answer the question, it it ABI to some kind of FW interface
> > > or something?
> > >
> > > *HOW* did two fields get overlapped onto a single u16?? The compiler
> > > won't do this..
> > >
> >
> > It is an ABI to the device for port attributes. The device gives us back
> > this structure for query port verb. The response from the device is
> > memcopied into this pvrdma_port_attr structure. So both the bytes
> > representing active_speed and phys_state from the device are copied
> > into the single u16 in this structure.
>
> So it is ABI and it shouldn't have been changed, point at the stuff
> that made it ABI and revert the structure layout change..

How will it work for the new IBTA speed?

Thanks

>
> Jason