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Re: [Qemu-devel] Are there any IOMMU emulation in QEMU for x86 platform
From: |
Knut Omang |
Subject: |
Re: [Qemu-devel] Are there any IOMMU emulation in QEMU for x86 platform |
Date: |
Mon, 02 Dec 2013 10:37:29 +0100 |
On Wed, 2013-11-20 at 00:01 +0000, Jiang, Yunhong wrote:
>
> > -----Original Message-----
> > From: Paolo Bonzini [mailto:address@hidden On Behalf Of Paolo
> > Bonzini
> > Sent: Tuesday, November 19, 2013 1:14 AM
> > To: Jiang, Yunhong
> > Cc: address@hidden; address@hidden;
> > address@hidden
> > Subject: Re: Are there any IOMMU emulation in QEMU for x86 platform
> >
> > Il 19/11/2013 07:34, Jiang, Yunhong ha scritto:
> > > Hi, all
> > > I noticed there are several patchset has been sent out about IOMMU
> > emulation like
> > > http://lists.gnu.org/archive/html/qemu-devel/2011-10/msg03764.html,
> > > http://lists.gnu.org/archive/html/qemu-devel/2011-01/msg03196.html .
> > > Also I noticed that PPC platform has IOMMU emulation support in QEMU
> > > already. Are there any plan to support IOMMU emulation in QEMU for
> > x86 now?
> >
> > Not that I know of. Of course, patches are welcome.
I have been working on some code to emulate an Intel IOMMU - I have a
simple patch to SeaBIOS to provide a minimal DMAR table and skeleton
device code that answers about what the kernel would expect to the Intel IOMMU
Linux driver boot a VM with intel_iommu=on
I got as far as when I was going to try to figure out how to emulate the
interrupt remapping
which appears to be where the kernel gets stuck after I got past the initial
setup
and invalidation cycles.
Unfortunately I haven't had much time to work on it lately, but I'll be
happy to share what I have so far. I have created branches of qemu and seabios
here:
git://github.com/knuto/seabios.git
git://github.com/knuto/qemu.git
> > > And also, does it requires the real host platform have the IOMMU to
> > support the QEMU IOMMU emulation? Or it will be a purely software
> > emulation?
> >
> > For emulated devices it could be purely software.
I picture that the way forward should include some way of adapting to
what "real" hardware that exists and use the "best" approach from that.
> > Nested device
> > assignment would require a host IOMMU, and would require the host
> > IOMMU driver to do some kind of shadow-paging.
> >
> > Paolo
>
Knut Omang
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