Re: KVM devices assignment; PCIe AER?

Alex Williamson
2010-10-26T18:10:43Z

On Tue, Oct 26, 2010 at 10:41 AM, etmartin101 <etmartin101@gmail.com> wrote:
> Chris, Michael et al.
>
> Part of the project I'm working on, we are looking at extending the
> device assignment capabilities to provide support for PCIe AER.
> Ideally, the host would register for AER (for every assigned devices) and
> pass them up to Qemu.
>
> As of now, one of the problem is that KVM is not a driver for the
> assigned devices. I've seen Chris's slides from KVM conf 2010 but I
> haven't seen any patches or discussion on that topic...
>
> On another front, I've seen the work from Michael around 'uio_pci_generic'
> and some of his comments:
>  " It's expected that more features of interest to virtualization will be
>  added to this driver in the future. Possibilities are: mmap for device
>  resources, MSI/MSI-X, eventfd (to interface with kvm), iommu."
>
> I think that extending 'uio_pci_generic' to support AER is relatively
> straight forward (assuming eventfd support from UIO).

A lot of work has been going into a new "VFIO" driver that has taken
over in the virtualization direction that uio_pci_generic was starting
to go. Search the mailing list for it. That's probably where we'd
want to focus AER efforts. I posted a qemu VFIO driver RFC a few
months ago and I'm still actively working on it. We currently pass
the device capabilities to the guest via an emulation layer in the
VFIO kernel driver. This layer might be going away as we try to
simplify the kernel side, which would mean more capability work in
qemu. We also need the update to the Q35 chipset that Isaku is
working on to be able to have an express root port to signal AER
events.

Alex