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Subject: Re: [PATCH v3 11/20] RDMA/core: introduce
 ib_dma_pci_p2p_dma_supported()
To:     Logan Gunthorpe <logang@deltatee.com>,
        <linux-kernel@vger.kernel.org>, <linux-nvme@lists.infradead.org>,
        <linux-block@vger.kernel.org>, <linux-pci@vger.kernel.org>,
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CC:     Stephen Bates <sbates@raithlin.com>,
        Christoph Hellwig <hch@lst.de>,
        "Dan Williams" <dan.j.williams@intel.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        =?UTF-8?Q?Christian_K=c3=b6nig?= <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>,
        Martin Oliveira <martin.oliveira@eideticom.com>,
        Chaitanya Kulkarni <ckulkarnilinux@gmail.com>
References: <20210916234100.122368-1-logang@deltatee.com>
 <20210916234100.122368-12-logang@deltatee.com>
From:   Max Gurtovoy <mgurtovoy@nvidia.com>
Message-ID: <18c0747f-a026-e018-afa8-e090efe69675@nvidia.com>
Date:   Wed, 6 Oct 2021 01:31:06 +0300
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Logan,

On 9/17/2021 2:40 AM, Logan Gunthorpe wrote:
> Introduce the helper function ib_dma_pci_p2p_dma_supported() to check
> if a given ib_device can be used in P2PDMA transfers. This ensures
> the ib_device is not using virt_dma and also that the underlying
> dma_device supports P2PDMA.
>
> Use the new helper in nvme-rdma to replace the existing check for
> ib_uses_virt_dma(). Adding the dma_pci_p2pdma_supported() check allows
> switching away from pci_p2pdma_[un]map_sg().
>
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> ---
>   drivers/nvme/target/rdma.c |  2 +-
>   include/rdma/ib_verbs.h    | 11 +++++++++++
>   2 files changed, 12 insertions(+), 1 deletion(-)

Looks good,

Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com>