On Wed, Dec 6, 2017 at 11:28 PM, achiad shochat <achiad.mellanox@xxxxxxxxx> wrote: > On 5 December 2017 at 21:20, Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: >> On Tue, Dec 05, 2017 at 11:59:17AM +0200, achiad shochat wrote: >>> Then we'll have a single solution for both netvsc and virtio (and any >>> other PV device). >>> And we could handle the VF DMA dirt issue agnostically. >> >> For the record, I won't block patches adding this kist to virtio >> on the basis that they must be generic. It's not a lot >> of code, implementation can come first, prettify later. > > It's not a lot of code either way. > So I fail to understand why not to do it right from the beginning. > For the record... What isn't a lot of code? If you are talking about the DMA dirtying then I would have to disagree. The big problem with the DMA is that we have to mark a page as dirty and non-migratable as soon as it is mapped for Rx DMA. It isn't until the driver has either unmapped the page or the device has been disabled that we can then allow the page to be migrated for being dirty. That ends up being the way we have to support this if we don't have the bonding solution. With the bonding solution we could look at doing a lightweight DMA dirtying which would just require flagging pages as dirty after an unmap or sync call is performed. However it requires that we shut down the driver/device before we can complete the migration which means we have to have the paravirtualized fail-over approach. As far as indicating that the interfaces are meant to be enslaved I wonder if we couldn't look at tweaking the PCI layout of the guest and use that to indicate that a given set of interfaces are meant to be bonded. For example the VFs are all meant to work as a part of a multi-function device. What if we were to make virtio-net function 0 of a PCI/PCIe device, and then place any direct assigned VFs that are meant to be a part of the bond in functions 1-7 of the device? Then it isn't too far off from the model we have on the host where if the VF goes away we would expect to see the traffic on the PF that is usually occupying function 0 of a given device. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
