lkml.org 
[lkml]   [2015]   [Nov]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v3 0/3] virtio DMA API core stuff
On Fri, Nov 20, 2015 at 08:56:46AM +0200, Michael S. Tsirkin wrote:
> On Thu, Nov 19, 2015 at 01:59:05PM -0800, Andy Lutomirski wrote:
> > On Nov 19, 2015 5:45 AM, "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > >
> > > On Tue, Oct 27, 2015 at 11:38:57PM -0700, Andy Lutomirski wrote:
> > > > This switches virtio to use the DMA API unconditionally. I'm sure
> > > > it breaks things, but it seems to work on x86 using virtio-pci, with
> > > > and without Xen, and using both the modern 1.0 variant and the
> > > > legacy variant.
> > >
> > > So thinking hard about it, I don't see any real drawbacks to making this
> > > conditional on a new feature bit, that Xen can then set..
> >
> > Can you elaborate? If I run QEMU, hosting Xen, hosting Linux, and the
> > virtio device is provided by QEMU, then how does Xen set the bit?
>
> You would run QEMU with the appropriate flag. E.g.
> -global virtio-pci,use_platform_dma=on

Or Xen code within QEMU can tweak this global internally
so users don't need to care.

> > Similarly, how would Xen set the bit for a real physical device?
> >
> >
> > --Andy
>
> There's no need to set bits for physical devices I think: from security
> point of view, using them from a VM isn't very different from using them
> from host.
>
>
>
> --
> MST


\
 
 \ /
  Last update: 2015-11-20 09:01    [W:0.166 / U:0.024 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site