Re: [PATCH rdma-next 4/4] RDMA/irdma: Add support for revocable pinned dmabuf import

[Leon Romanovsky <leon@kernel.org>]

On Wed, Feb 25, 2026 at 09:07:05PM +0000, Jacob Moroni wrote:
> Use the new API to support importing pinned dmabufs from exporters
> that require revocation, such as VFIO. The revoke semantic is
> achieved by issuing a HW invalidation command but not freeing
> the key. This prevents further accesses to the region (they will
> result in an invalid key AE), but also keeps the key reserved
> until the region is actually deregistered (i.e., ibv_dereg_mr)
> so that a new MR registration cannot acquire the same key.
> 
> Tested with lockdep+kasan and a memfd backed dmabuf.
> 
> Signed-off-by: Jacob Moroni <jmoroni@google.com>
> ---
>  drivers/infiniband/hw/irdma/main.h  |  1 +
>  drivers/infiniband/hw/irdma/verbs.c | 71 ++++++++++++++++++++++++++++-
>  2 files changed, 71 insertions(+), 1 deletion(-)

<...>

>   * irdma_dereg_mr - deregister mr
>   * @ib_mr: mr ptr for dereg
> @@ -3911,6 +3977,9 @@ static int irdma_dereg_mr(struct ib_mr *ib_mr, struct ib_udata *udata)
>  	struct irdma_pbl *iwpbl = &iwmr->iwpbl;
>  	int ret;
>  
> +	if (iwmr->region && iwmr->region->is_dmabuf)
> +		return irdma_dereg_mr_dmabuf(iwdev, iwmr);

I wonder if you really need to leak umem properties and can't use
existing irdma_dereg_mr(). ib_umem_release() handles both regular and dmabuf correctly.

Thanks

> +
>  	if (iwmr->type != IRDMA_MEMREG_TYPE_MEM) {
>  		if (iwmr->region) {
>  			struct irdma_ucontext *ucontext;
> -- 
> 2.53.0.414.gf7e9f6c205-goog
>