Re: [PATCH for-rc] IB/hfi: Only read capability registers if the capability exists

[Jason Gunthorpe <jgg@ziepe.ca>]

On Fri, Dec 22, 2017 at 08:47:20AM -0800, Dennis Dalessandro wrote:
> From: Michael J. Ruhl <michael.j.ruhl@intel.com>
> 
> During driver init, various registers are saved to allow restoration
> after an FLR or gen3 bump.  Some of these registers are not available
> in some circumstances (i.e. Virtual machines).
> 
> Delete unnecessary register read/write, and only access register if
> the capability exists.
> 
> Cc: <stable@vger.kernel.org> # 4.14.x
> Fixes: a618b7e40af2 ("IB/hfi1: Move saving PCI values to a separate function")
> Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
> Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
>  drivers/infiniband/hw/hfi1/hfi.h  |    1 -
>  drivers/infiniband/hw/hfi1/pcie.c |   30 ++++++++++++------------------
>  2 files changed, 12 insertions(+), 19 deletions(-)

Since we are getting late in the RC cycle can you help me clarify the
user visible bug here? No need to resend

I'm guessing when hfi1 is used in a virtual machine with passthrough
(SRIOV?) it fails in ?? way?

Jason