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

Michael S. Tsirkin
2020-04-29T09:52:17Z

On Wed, Apr 29, 2020 at 03:14:10PM +0530, Srivatsa Vaddagiri wrote:
> * Michael S. Tsirkin <mst@redhat.com> [2020-04-29 02:50:41]:
>
> > So it seems that with modern Linux, all one needs
> > to do on x86 is mark the device as untrusted.
> > It's already possible to do this with ACPI and with OF - would that be
> > sufficient for achieving what this patchset is trying to do?
>
> In my case, its not sufficient to just mark virtio device untrusted and thus
> activate the use of swiotlb. All of the secondary VM memory, including those
> allocate by swiotlb driver, is private to it.

So why not make the bounce buffer memory shared then?

> An additional piece of memory is
> available to secondary VM which is shared between VMs and which is where I need
> swiotlb driver to do its work.
>
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