I just wanted to clarify the hotplug VFIO is not the problem, as I can see it, but the unplug. When attaching a device the current VFIO code will be used, but there is no code for doing the IOMMU unmapping when unplugging.
On Wed, Feb 8, 2017 at 3:43 PM, Alejandro Lucero < alejandro.luc...@netronome.com> wrote: > Hi Eelco, > > On Wed, Feb 8, 2017 at 9:41 AM, Eelco Chaudron <echaud...@redhat.com> > wrote: > >> Hi Anatoly, >> >> This will be great... If you want I can do some testing on (early) >> patches if required. >> >> Also do you know why it is currently not supported, i.e. what are the >> limitations? >> >> Thanks, >> > > I assume your reply was to my previous email and not to Anatoly's one. My > apologies if this assumption is wrong. > By the way, you did not reply to the list, but I'm doing to do so because > this could be interesting to other people. Also, I'm CCing hotplug UIO > developer, Tetsuya Mukawa, since there is no a specific maintainer for this > functionality. > > I think the main problem for supporting VFIO hotplug is to deal with what > VFIO does, this is IOMMU mappings. > There is no code for doing so, and although the implementation would use > most of the code already there for UIO hotplug, which is basically related > to unmapping PCI resources, and the interrupt part will be likely quite > similar, the IOMMU unmapping requires more work. > > I dare to say this is the main reason for not having VFIO hotplug support > right now. Maybe Tetsuya can confirm this or give us other reasons. > > >> >> Eelco >> >> >> >> On 07/02/17 10:29, Alejandro Lucero wrote: >> >> It seems none is working on this VFIO support. >> >> I will work on this if there is no reply to this thread saying the >> opposite the next days. >> >> On Thu, Feb 2, 2017 at 12:58 PM, Eelco Chaudron <echaud...@redhat.com> >> wrote: >> >>> On 02/02/17 13:05, Burakov, Anatoly wrote: >>> >>>> Hi Eelco, >>>> >>>> Please forgive me my ignorance on this matter, but doesn't it work at >>>> the moment? I would assume that if regular PCI hotplug works (with >>>> igb_uio), then so would hotplug with VFIO, as it basically utilizes the >>>> same PCI infrastructure igb_uio does. That said, I'm not aware of any >>>> patches submitted that had to do with VFIO and hotplug, so I guess the >>>> answer is, not at the moment. >>>> >>>> Thanks, >>>> Anatoly >>>> >>> I was asking as the documentation explicitly mentions its not supported. >>> http://dpdk.org/doc/guides/prog_guide/port_hotplug_framework >>> .html#hotplug >>> >>> - "To detach a port, the port should be backed by a device that igb_uio >>> manages. VFIO is not supported." >>> >>> I could not find any specific reason why it's not supported, so if some >>> one can explain this it would help also... >>> >>> Cheers, >>> >>> Eelco >>> >>> >>> >> >> >
