Re: [libvirt] [PATCH v2 7/8] Move the detach of PCI device to the beginnging of live hotplug

On May 20, 2016 12:36 AM, "Laine Stump" <laine(a)laine.org&gt; wrote: from their host driver, even if you're only assigning one or another of them to the guest? deal with (currently you can assign a single device from an iommu group with many devices, but managed='yes' won't work for it. That would require some other sort of managed mode, like "managed='group'" or something, but more elaborate managed modes have already been NACKed on the list (I posted an RFC patch for "managed='detach'" at the request of someone else - it would detach the device from the host driver before assignment, but not reattach it afterwards. This was deemed inappropriate and unnecessary.) devices without any clue to do so in the config - it's because you can't expect the user to know which devices are in the same iommu group as the one you want to assign, and you don't want to just automatically/silent detach one that is essential for continued operation of the host. assigned to the guest. other card functions is necessary. detach all the devices that are going to be assigned, then assign them all, with the one going to function 0 being last. saying different SRIOV functions(all with function zero) be hotplugged as need to do that. particular, just saying that the way multifunction device assignment is done in qemu is to assign all the non-0 functions, then assign function 0. But that was just an incidental part of the conversation. The important part is that you first detach from the host all devices to be assigned, then you assign them all. The SRIOV devices are single function and they dont have the dependency of "other" function to be detached before the device_add. So, they can be detached in qemuDomainAttachNetDevice() itself. The case I am talking about is, should we be supporting the devices belonging to different iommu groups be hotplugged as a singled card into guest? Say 5 SRIOV functions hotplugged as a single Card. I am not sure we should allow that. Unlike I mentioned, in such case too we can detach in qemuDomainAttachNetDevice() itself and expect it to work.