Re: [Qemu-devel] Virtual IOMMU + Virtio-net devices in a Windows VM doesn't work

[Jintack Lim]

Thanks, Yan.

On Sun, Jul 29, 2018 at 7:44 AM Yan Vugenfirer <address@hidden> wrote:
>
>
>
> > On 26 Jul 2018, at 05:53, Jintack Lim <address@hidden> wrote:
> >
> > Hi Peter,
> >
> > On Tue, Jul 24, 2018 at 1:55 AM Peter Xu <address@hidden> wrote:
> >>
> >> On Mon, Jul 23, 2018 at 04:13:18PM -0400, Jintack Lim wrote:
> >>> Hi,
> >>>
> >>> I'm running a Windows VM on top of KVM on x86, and one of virtio-net
> Hi,
>
> What Windows OS are you using? Keep in mind that IOMMU support in Windows 
> drivers will work in Windows 10 and Windows Server 2016.
> What’s the version of the virtio-win drivers are you using (should be build 
> 150 and up, or to include the following commit: 
> https://github.com/virtio-win/kvm-guest-drivers-windows/commit/eac3270d10924903ff38a08fcdaa252604d2e4a9)?
>

I'm using Windows Server 2016, and the virtio-win driver version is
0.1.149, which is the latest binary from here [1]. I'll try to build
150, and test it again. Thanks for the confirmation!

[1] 
https://docs.fedoraproject.org/quick-docs/en-US/creating-windows-virtual-machines-using-virtio-drivers.html

> Best regards,
> Yan.
>
> >>> device in the Windows VM doesn't seem to work. I provided virtual
> >>> IOMMU and two virtio-net devices to the VM: one bypassing the virtual
> >>> IOMMU and the other one behind the virtual IOMMU[1]. It turned out
> >>> that the virtio-net device behind virtual IOMMU didn't work while the
> >>> one bypassing the virtual IOMMU worked well. In a linux VM with the
> >>> same configuration, both of virtio-net device worked well.
> >>>
> >>> I found that there is a subtle difference between virtio-net devices
> >>> bypassing and behind virtual IOMMU in a Linux VM. The lscpu command in
> >>> the Linux VM shows different device names for them; the first line is
> >>> for the bypassing one, and the second line is for the one behind the
> >>> virtual IOMMU
> >>>
> >>> 00:03.0 Ethernet controller: Red Hat, Inc Virtio network device
> >>> 01:00.0 Ethernet controller: Red Hat, Inc Device 1041 (rev 01)
> >>>
> >>> I wonder if this difference somehow caused the problem in the Windows
> >>> VM. I've installed the latest virtio drivers (0.1.149) from the fedora
> >>> project [2]
> >>>
> >>> Any thoughts?
> >>>
> >>> I'm using v4.15 Linux kernel as a host, and QEMU 2.11.0.
> >>
> >> Have you tried the latest QEMU?
> >>
> >
> > I just tried the latest QEMU, but observed the same symptom.
> >
> >> Also CC Jason and Michael.
> >
> > Thanks!
> >
> >>
> >>>
> >>> Thanks,
> >>> Jintack
> >>>
> >>> [1] https://wiki.qemu.org/Features/VT-d
> >>> [2] 
> >>> https://docs.fedoraproject.org/quick-docs/en-US/creating-windows-virtual-machines-using-virtio-drivers.html
> >>>
> >>>
> >>
> >> Regards,
> >>
> >> --
> >> Peter Xu
> >>
> >
> >
>
>