[lkml]   [2020]   [Feb]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRE: [RFC PATCH 0/7] vfio/pci: SR-IOV support
Hi Alex,

Silly questions on the background:

> From: Alex Williamson <>
> Sent: Wednesday, February 5, 2020 7:06 AM
> Subject: [RFC PATCH 0/7] vfio/pci: SR-IOV support
> There seems to be an ongoing desire to use userspace, vfio-based
> drivers for both SR-IOV PF and VF devices.

Is this series to make PF be bound-able to vfio-pci even SR-IOV is
enabled on such PFs? If yes, is it allowed to assign PF to a VM? or
it can only be used by userspace applications like DPDK?

> The fundamental issue
> with this concept is that the VF is not fully independent of the PF
> driver. Minimally the PF driver might be able to deny service to the
> VF, VF data paths might be dependent on the state of the PF device,
> or the PF my have some degree of ability to inspect or manipulate the
> VF data. It therefore would seem irresponsible to unleash VFs onto
> the system, managed by a user owned PF.
> We address this in a few ways in this series. First, we can use a bus
> notifier and the driver_override facility to make sure VFs are bound
> to the vfio-pci driver by default. This should eliminate the chance
> that a VF is accidentally bound and used by host drivers. We don't
> however remove the ability for a host admin to change this override.
> The next issue we need to address is how we let userspace drivers
> opt-in to this participation with the PF driver. We do not want an
> admin to be able to unwittingly assign one of these VFs to a tenant
> that isn't working in collaboration with the PF driver. We could use
> IOMMU grouping, but this seems to push too far towards tightly coupled
> PF and VF drivers. This series introduces a "VF token", implemented
> as a UUID, as a shared secret between PF and VF drivers. The token
> needs to be set by the PF driver and used as part of the device
> matching by the VF driver. Provisions in the code also account for
> restarting the PF driver with active VF drivers, requiring the PF to
> use the current token to re-gain access to the PF.

How about the scenario in which PF driver is vfio-based userspace
driver but VF drivers are mixed. This means not all VFs are bound
to vfio-based userspace driver. Is it also supported here? :-)

Yi Liu
 \ /
  Last update: 2020-02-05 08:58    [W:0.137 / U:0.352 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site