Re: [PATCH 14/16] nvme-rdma: Ensure dma support when using p2pdma

[Jason Gunthorpe]

On Thu, Apr 08, 2021 at 11:01:21AM -0600, Logan Gunthorpe wrote:
> Ensure the dma operations support p2pdma before using the RDMA
> device for P2PDMA. This allows switching the RDMA driver from
> pci_p2pdma_map_sg() to dma_map_sg_p2pdma().
> 
> Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
>  drivers/nvme/target/rdma.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvme/target/rdma.c b/drivers/nvme/target/rdma.c
> index 6c1f3ab7649c..3ec7e77e5416 100644
> +++ b/drivers/nvme/target/rdma.c
> @@ -414,7 +414,8 @@ static int nvmet_rdma_alloc_rsp(struct nvmet_rdma_device *ndev,
>  	if (ib_dma_mapping_error(ndev->device, r->send_sge.addr))
>  		goto out_free_rsp;
>  
> -	if (!ib_uses_virt_dma(ndev->device))
> +	if (!ib_uses_virt_dma(ndev->device) &&
> +	    dma_pci_p2pdma_supported(&ndev->device->dev))

ib_uses_virt_dma() should not be called by nvme and this is using the
wrong device pointer to query for DMA related properties.

I suspect this wants a ib_dma_pci_p2p_dma_supported() wrapper like
everything else.

Jason