This change allows the RDMA stack to use physical resource numbers if they
are passed up from the device. This is accomplished by separating the
concept of the QP number from the QP handle. Previously, the two were the
same, as the QP number was exposed to the guest and also used to reference
a virtual QP in the device backend.

With physical resource numbers exposed, the QP number given to the guest
is the number assigned from the physical HCA's QP, while the QP handle is
still the internal handle used to reference a virtual QP. Regardless of
whether the device is exposing physical ids, the driver will still try to
pick up the QP handle from the backend if possible. The MR keys exposed to
the guest will also be the MR keys created by the physical HCA, instead of
virtual MR keys. The distinction between handle and keys is already
present for MRs so there is no need to do anything special here.

A new version of the create QP response has been added to the device API
to pass up the QP number and handle. The driver will also report these to
userspace in the udata response if userspace supports it or not create the
queuepair if not. I also had to do a refactor of the destroy qp code to
reuse it if we fail to copy to userspace.

Link: https://lore.kernel.org/r/20191028181444.19448-1-aditr@vmware.comReviewed-by: Jorgen Hansen <jhansen@vmware.com>
Signed-off-by: Adit Ranadive <aditr@vmware.com>
Signed-off-by: Bryan Tan <bryantan@vmware.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>