RDMA/rxe: Reject IB_ACCESS_ON_DEMAND changes after MR creation

Whether an MR is an ODP MR is decided once, at registration time:
rxe_reg_user_mr() picks rxe_odp_mr_init_user() over rxe_mr_init_user()
based on IB_ACCESS_ON_DEMAND, and only the former builds an ib_umem_odp
via ib_umem_odp_get(). The umem cannot change type afterwards, and
is_odp_mr() reads mr->umem->is_odp.

Two paths assign mr->access after that point and can leave it
describing an MR type the umem does not have:

rxe_rereg_user_mr() with IB_MR_REREG_ACCESS overwrites mr->access with
the caller's value, and IB_ACCESS_ON_DEMAND is part of
RXE_ACCESS_SUPPORTED_MR, so userspace can set the flag on a plain MR or
clear it on an ODP MR while the umem stays what it was.

rxe_reg_fast_mr() takes mr->access from the REG_MR work request
unmasked and moves the MR to RXE_MR_STATE_VALID, on an MR that
rxe_mr_init_fast() left with a NULL umem.

Reject IB_ACCESS_ON_DEMAND in both, so mr->access carries the flag only
for an MR that has an ODP umem and the flag can be used to identify one.

Fixes: 544c7f62cf32 ("RDMA/rxe: Implement rereg_user_mr")
Signed-off-by: Norbert Szetei <norbert@doyensec.com>
Link: https://patch.msgid.link/20260923-rxe-advise-mr-v3-v3-1-95e1a4077e4d@doyensec.com
Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Signed-off-by: Leon Romanovsky <leon@kernel.org>

0 files changed, 0 insertions, 0 deletions