Re: [Qemu-devel] [Xen-devel] [PATCH RFC V1 00/11] Xen PCI Passthrough

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Tue, 4 Oct 2011, Anthony Liguori wrote:
> On 10/04/2011 09:58 AM, Avi Kivity wrote:
> > On 10/04/2011 04:51 PM, Anthony PERARD wrote:
> >> Hi all,
> >>
> >> This patch series introduce the PCI passthrough for Xen.
> >>
> >> First, we have HostPCIDevice that help to access one PCI device of the 
> >> host.
> >>
> >> Then, there are several additions in the QEMU code. One is 
> >> qemu_run_one_timer
> >> to run a specific timer. It is used by PCI passthrough to run a timer about
> >> power management. Another is pci_check_bar_overlap.
> >>
> >> There are also several change in pci_ids and pci_regs.
> >>
> >> Last part, but not least, the PCI passthrough device himself. Cut in 3 
> >> parts
> >> (or file), there is one to take care of the initialisation of a passthrough
> >> device. The second one handle everything about the config address space, 
> >> there
> >> are specifics functions for every config register. The third one is to 
> >> handle
> >> MSI.
> >>
> >> I'm still working on setting a PCI passthrough device through QMP from 
> >> libxl
> >> (xen tool stack). It is just a call to device_add, with the driver 
> >> parametter
> >> hostaddr="0000:00:1b.0".
> >>
> >> There is some minor things missing:
> >> - copyright header
> >> - PCI IO space multiplexer
> >>
> >>
> >
> > We also have pci passthrough in qemu-kvm (I think based on the same Neocleus
> > code). Rather than having two pci assignment implementations, I think we 
> > should
> > have just one, with the differences (programming the hypervisor) abstracted 
> > at
> > that level.
> 
> I agree in principle but how close is qemu-kvm pci passthrough to a mergable 
> state?  Would it make sense to merge the Xen code first and then abstract it?

I think it should be fairly easy to abstract the current xen code: just
a matter of providing memory, ioport and interrupt mapping functions.

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