From: Christoph Hellwig <hch@infradead.org>
To: Maxime Coquelin <maxime.coquelin@redhat.com>
Cc: mst@redhat.com, jasowang@redhat.com, xuanzhuo@linux.alibaba.com,
xieyongji@bytedance.com, axboe@kernel.dk,
gregkh@linuxfoundation.org, brauner@kernel.org,
lstoakes@gmail.com, virtualization@lists.linux.dev,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
david.marchand@redhat.com
Subject: Re: [PATCH] vduse: implement DMA sync callbacks
Date: Tue, 20 Feb 2024 01:01:36 -0800 [thread overview]
Message-ID: <ZdRqcIRmDD-70ap3@infradead.org> (raw)
In-Reply-To: <20240219170606.587290-1-maxime.coquelin@redhat.com>
On Mon, Feb 19, 2024 at 06:06:06PM +0100, Maxime Coquelin wrote:
> Since commit 295525e29a5b ("virtio_net: merge dma
> operations when filling mergeable buffers"), VDUSE device
> require support for DMA's .sync_single_for_cpu() operation
> as the memory is non-coherent between the device and CPU
> because of the use of a bounce buffer.
>
> This patch implements both .sync_single_for_cpu() and
> sync_single_for_device() callbacks, and also skip bounce
> buffer copies during DMA map and unmap operations if the
> DMA_ATTR_SKIP_CPU_SYNC attribute is set to avoid extra
> copies of the same buffer.
vduse really needs to get out of implementing fake DMA operations for
something that is not DMA.
next prev parent reply other threads:[~2024-02-20 9:01 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-19 17:06 [PATCH] vduse: implement DMA sync callbacks Maxime Coquelin
2024-02-20 9:01 ` Christoph Hellwig [this message]
2024-02-21 8:47 ` Maxime Coquelin
2024-02-22 20:29 ` Michael S. Tsirkin
2024-02-23 8:03 ` Christoph Hellwig
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