Re: [PATCH 1/1] RDMA/irdma: Add support for dmabuf pin memory regions

[Jason Gunthorpe <jgg@ziepe.ca>]

On Mon, Jan 02, 2023 at 08:34:33PM -0500, Zhu Yanjun wrote:
> From: Zhu Yanjun <yanjun.zhu@linux.dev>
> 
> This is a followup to the EFA dmabuf[1]. Irdma driver currently does
> not support on-demand-paging(ODP). So it uses habanalabs as the
> dmabuf exporter, and irdma as the importer to allow for peer2peer
> access through libibverbs.
> 
> In this commit, the function ib_umem_dmabuf_get_pinned() is used.
> This function is introduced in EFA dmabuf[1] which allows the driver
> to get a dmabuf umem which is pinned and does not require move_notify
> callback implementation. The returned umem is pinned and DMA mapped
> like standard cpu umems, and is released through ib_umem_release().
> 
> [1]https://lore.kernel.org/lkml/20211007114018.GD2688930@ziepe.ca/t/
> 
> Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
> ---
>  drivers/infiniband/hw/irdma/verbs.c | 158 ++++++++++++++++++++++++++++
>  1 file changed, 158 insertions(+)
> 
> diff --git a/drivers/infiniband/hw/irdma/verbs.c b/drivers/infiniband/hw/irdma/verbs.c
> index f6973ea55eda..76dc6e65930a 100644
> --- a/drivers/infiniband/hw/irdma/verbs.c
> +++ b/drivers/infiniband/hw/irdma/verbs.c
> @@ -2912,6 +2912,163 @@ static struct ib_mr *irdma_reg_user_mr(struct ib_pd *pd, u64 start, u64 len,
>  	return ERR_PTR(err);
>  }
>  
> +struct ib_mr *irdma_reg_user_mr_dmabuf(struct ib_pd *pd, u64 start,
> +				       u64 len, u64 virt,
> +				       int fd, int access,
> +				       struct ib_udata *udata)
> +{
> +	struct irdma_device *iwdev = to_iwdev(pd->device);
> +	struct irdma_ucontext *ucontext;
> +	struct irdma_pble_alloc *palloc;
> +	struct irdma_pbl *iwpbl;
> +	struct irdma_mr *iwmr;
> +	struct irdma_mem_reg_req req;
> +	u32 total, stag = 0;
> +	u8 shadow_pgcnt = 1;
> +	bool use_pbles = false;
> +	unsigned long flags;
> +	int err = -EINVAL;
> +	struct ib_umem_dmabuf *umem_dmabuf;
> +
> +	if (len > iwdev->rf->sc_dev.hw_attrs.max_mr_size)
> +		return ERR_PTR(-EINVAL);
> +
> +	if (udata->inlen < IRDMA_MEM_REG_MIN_REQ_LEN)
> +		return ERR_PTR(-EINVAL);
> +
> +	umem_dmabuf = ib_umem_dmabuf_get_pinned(pd->device, start, len, fd,
> +						access);
> +	if (IS_ERR(umem_dmabuf)) {
> +		err = PTR_ERR(umem_dmabuf);
> +		ibdev_dbg(&iwdev->ibdev, "Failed to get dmabuf umem[%d]\n", err);
> +		return ERR_PTR(err);
> +	}
> +
> +	if (ib_copy_from_udata(&req, udata, min(sizeof(req), udata->inlen))) {
> +		ib_umem_release(&umem_dmabuf->umem);
> +		return ERR_PTR(-EFAULT);
> +	}
> +
> +	iwmr = kzalloc(sizeof(*iwmr), GFP_KERNEL);
> +	if (!iwmr) {
> +		ib_umem_release(&umem_dmabuf->umem);
> +		return ERR_PTR(-ENOMEM);
> +	}
> +
> +	iwpbl = &iwmr->iwpbl;
> +	iwpbl->iwmr = iwmr;
> +	iwmr->region = &umem_dmabuf->umem;
> +	iwmr->ibmr.pd = pd;
> +	iwmr->ibmr.device = pd->device;
> +	iwmr->ibmr.iova = virt;
> +	iwmr->page_size = PAGE_SIZE;
> +
> +	if (req.reg_type == IRDMA_MEMREG_TYPE_MEM) {
> +		iwmr->page_size = ib_umem_find_best_pgsz(iwmr->region,
> +							 iwdev->rf->sc_dev.hw_attrs.page_size_cap,
> +							 virt);

You can't call rdma_umem_for_each_dma_block() without also calling
this function to validate that the page_size passed to
rdma_umem_for_each_dma_block() is correct.

This seems to be an existing bug, please fix it.

Also, is there a reason this code is all duplicated from
irdma_reg_user_mr? Please split things up like the other drivers to
obtain the umem then use shared code to process the umem as required.

Jason