[vfio-users] vfio passthrough devices behind pcie switcher problem

[rhett rhett]

i have two guest , a windows 2008 server and a centos 7.2 . in windows, the
device manager said the gpu can't start ,error code 10.
in centos, when i run nvidia-smi,  it said no device found.

no specil vm configurations,  whit the same config, i can use gpu
successfully in my two gpu server. the biggest different is , that server
is no pcie switcher.

2017-03-08 11:55 GMT+08:00 Alex Williamson <alex.williamson at redhat.com>:

> On Wed, 8 Mar 2017 11:26:17 +0800
> rhett rhett <rhett.kernel at gmail.com> wrote:
>
> > two gpus share the same irq , i found the reason. because the msi be
> > disabled later , so irq 140 is being reused.
> >
> > but i don't know why somebady calls vfio_pci_ioctl to disable the msi.
>
> vfio just does what the guest requests, but you're really providing
> hardly any more information than when you asked off list.  My wild
> guess, is that maybe you're running a Windows guest and not configuring
> the VM for a vCPU type where Windows supports MSI.  For more
> assistance, please provide basic information, like the QEMU command
> line or VM XML, also the PCI information from the host (sudo lspci
> -vvv), and of course any error codes in the guest or an actual
> description of how the device doesn't work in the guest.  Thanks,
>
> Alex
>
>
> > 2017-03-08 10:55 GMT+08:00 rhett rhett <rhett.kernel at gmail.com>:
> >
> > > i have a question about vfio , here is my description.
> > >
> > > i have 8 gpus in my server machine ,  but they are all behind a pcie
> > > bridge.  when i make a vfio passthrough , i can't use the gpus in my
> guest
> > > os.
> > > dmesg shows the following message
> > >
> > > [  662.208072] vfio-pci 0000:87:00.0: irq 140 for MSI/MSI-X
> > > [  725.761623] vfio-pci 0000:04:00.0: irq 140 for MSI/MSI-X
> > >
> > > i started two vm , one use 87 and another use 04,  dmesg shows that
> they
> > > share the same irq 140 . is this normal ?
> > >
> > > i also saw the iommu groups, each gpu stays in a separate group， and
> with
> > > no other device in group. so this means ACS works correctly ?
> > >
> > > hope to get your helps !
> > >
>
>
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