linux-kernel - Re: [PATCH 5/5] virtio: Add bounce DMA ops

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Message-ID: <20200430152008.GB872@char.us.oracle.com>
Date:   Thu, 30 Apr 2020 11:20:08 -0400
From:   Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     Srivatsa Vaddagiri <vatsa@...eaurora.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>, tsoni@...eaurora.org,
        virtio-dev@...ts.oasis-open.org, jan.kiszka@...mens.com,
        jasowang@...hat.com, christoffer.dall@....com,
        virtualization@...ts.linux-foundation.org, alex.bennee@...aro.org,
        iommu@...ts.linux-foundation.org, stefano.stabellini@...inx.com,
        will@...nel.org, linux-kernel@...r.kernel.org,
        pratikp@...eaurora.org
Subject: Re: [PATCH 5/5] virtio: Add bounce DMA ops

On Wed, Apr 29, 2020 at 06:20:48AM -0400, Michael S. Tsirkin wrote:
> On Wed, Apr 29, 2020 at 03:39:53PM +0530, Srivatsa Vaddagiri wrote:
> > That would still not work I think where swiotlb is used for pass-thr devices
> > (when private memory is fine) as well as virtio devices (when shared memory is
> > required).
> 
> So that is a separate question. When there are multiple untrusted
> devices, at the moment it looks like a single bounce buffer is used.
> 
> Which to me seems like a security problem, I think we should protect
> untrusted devices from each other.

There are two DMA pools code in Linux already - the TTM one for graphics
and the mm/dmapool.c - could those be used instead? Or augmented at least?