Re: Write to srvio_numvfs triggers kernel panic

[Leon Romanovsky <leon@kernel.org>]

On Sat, May 07, 2022 at 10:25:16AM +0000, Volodymyr Babchuk wrote:
> 
> 
> Jason Gunthorpe <jgg@ziepe.ca> writes:
> 
> > On Fri, May 06, 2022 at 03:17:22PM -0500, Bjorn Helgaas wrote:
> >
> >> > Modules linked in: xt_MASQUERADE iptable_nat nf_nat nf_conntrack nf_defrag_ipv6
> >> > nf_defrag_ipv4 libcrc32c iptable_filter crct10dif_ce nvme nvme_core at24
> >> > pci_endpoint_test bridge pdrv_genirq ip_tables x_tables ipv6
> >> >  CPU: 3 PID: 287 Comm: sh Not tainted 5.10.41-lorc+ #233
> >> >  Hardware name: XENVM-4.17 (DT)
> >                 ^^^^^^^^^^^^^^^^^
> >
> >> So this means the VF must have an SR-IOV capability, which sounds a
> >> little dubious.  From PCIe r6.0:
> >
> > Enabling SRIOV from within a VM is "exciting" - I would not be
> > surprised if there was some wonky bugs here.
> 
> Well, yes. But in this case, this VM has direct access to the PCIe
> controller. So it should not cause any troubles. I'll try baremetal
> setup, though. 

If I remember correctly, the VM software that runs on hypervisor needs
to filter PCI capabilities even for pass-through devices.

The vfio kernel module did this for QEMU, so something similar I would
expect from XEN too.

Thanks

> 
> 
> -- 
> Volodymyr Babchuk at EPAM