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Date:   Tue, 9 Feb 2021 09:26:23 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc:     Christoph Hellwig <hch@lst.de>,
        Martin Radev <martin.b.radev@gmail.com>,
        m.szyprowski@samsung.com, robin.murphy@arm.com,
        iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
        joro@8bytes.org, kirill.shutemov@linux.intel.com,
        thomas.lendacky@amd.com, robert.buhren@sect.tu-berlin.de,
        file@sect.tu-berlin.de, mathias.morbitzer@aisec.fraunhofer.de,
        virtualization@lists.linux-foundation.org, kvm@vger.kernel.org
Subject: Re: [PATCH] swiotlb: Validate bounce size in the sync/unmap path
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On Mon, Feb 08, 2021 at 12:14:49PM -0500, Konrad Rzeszutek Wilk wrote:
> > ring buffer or whatever because you know I/O will be copied anyway
> > and none of all the hard work higher layers do to make the I/O suitable
> > for a normal device apply.
> 
> I lost you here. Sorry, are you saying have a simple ring protocol
> (like NVME has), where the ring entries (SG or DMA phys) are statically
> allocated and whenever NVME driver gets data from user-space it
> would copy it in there?

Yes.  Basically extend the virtio or NVMe ring/queue concept to not just
cover commands and completions, but also the data transfers.