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Date:   Tue, 27 Apr 2021 16:47:53 -0300
From:   Jason Gunthorpe <jgg@ziepe.ca>
To:     Logan Gunthorpe <logang@deltatee.com>
Cc:     linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
        linux-block@vger.kernel.org, linux-pci@vger.kernel.org,
        linux-mm@kvack.org, iommu@lists.linux-foundation.org,
        Stephen Bates <sbates@raithlin.com>,
        Christoph Hellwig <hch@lst.de>,
        Dan Williams <dan.j.williams@intel.com>,
        Christian =?utf-8?B?S8O2bmln?= <christian.koenig@amd.com>,
        John Hubbard <jhubbard@nvidia.com>,
        Don Dutile <ddutile@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        Jakowski Andrzej <andrzej.jakowski@intel.com>,
        Minturn Dave B <dave.b.minturn@intel.com>,
        Jason Ekstrand <jason@jlekstrand.net>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Xiong Jianxin <jianxin.xiong@intel.com>,
        Bjorn Helgaas <helgaas@kernel.org>,
        Ira Weiny <ira.weiny@intel.com>,
        Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH 14/16] nvme-rdma: Ensure dma support when using p2pdma
Message-ID: <20210427194753.GU2047089@ziepe.ca>
References: <20210408170123.8788-1-logang@deltatee.com>
 <20210408170123.8788-15-logang@deltatee.com>
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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@deltatee.com>
>  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