linux-kernel - Re: [PATCH 3/3] virtio-blk: Consider dma_max_mapping

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Message-ID: <20190116141043.qbsdbdt72akxpdtj@suse.de>
Date:   Wed, 16 Jan 2019 15:10:43 +0100
From:   Joerg Roedel <jroedel@...e.de>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     Joerg Roedel <joro@...tes.org>, Jason Wang <jasowang@...hat.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>,
        virtualization@...ts.linux-foundation.org,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        iommu@...ts.linux-foundation.org, jfehlig@...e.com,
        jon.grimm@....com, brijesh.singh@....com
Subject: Re: [PATCH 3/3] virtio-blk: Consider dma_max_mapping_size() for
 maximum segment size

On Wed, Jan 16, 2019 at 09:05:40AM -0500, Michael S. Tsirkin wrote:
> On Tue, Jan 15, 2019 at 02:22:57PM +0100, Joerg Roedel wrote:
> > +	max_size = dma_max_mapping_size(&vdev->dev);
> > +
> 
> 
> Should this be limited to ACCESS_PLATFORM?
> 
> I see no reason to limit this without as guest can
> access any memory.

Actually, yes. This should be inside a use_dma_api check. I had it in
v1, but it went away without the vring layer for propagating the limit.
I'll add that again.

Thanks,

	Joerg