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

[Alex Williamson]

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 !
> >