Messages in this thread | | | Subject | Re: [PATCH v6 00/20] Add VFIO mediated device support and DEV-MSI support for the idxd driver | From | Dave Jiang <> | Date | Tue, 8 Jun 2021 09:02:58 -0700 |
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On 6/7/2021 12:11 PM, Jason Gunthorpe wrote: > On Mon, Jun 07, 2021 at 11:13:04AM -0700, Dave Jiang wrote: > >> So in step 1, we 'tag' the wq to be dedicated to guest usage and put the >> hardware wq into enable state. For a dedicated mode wq, we can definitely >> just register directly and skip the mdev step. For a shared wq mode, we can >> have multiple mdev running on top of a single wq. So we need some way to >> create more mdevs. We can either go with the existing established creation >> path by mdev, or invent something custom for the driver as Jason suggested >> to accomodate additional virtual devices for guests. We implemented the mdev >> path originally with consideration of mdev is established and has a known >> interface already. > It sounds like you could just as easially have a 'create new vfio' > file under the idxd sysfs.. Especially since you already have a bus > and dynamic vfio specific things being created on this bus.
Will explore this and using of 'struct vfio_device' without mdev.
> > Have you gone over this with Dan? > >> I think things become more complicated when we go from a dedicated wq to >> shared wq where the relationship of wq : mdev is 1 : 1 goes to 1 : N. Also >> needing to keep a consistent user config experience is desired, especially >> we already have such behavior since kernel 5.6 for host usages. So we really >> need try to avoid doing wq configuration differently just for "mdev" wqs. In >> the case suggested above, we basically just flipped the configuration steps. >> Mdev is first created through mdev sysfs interface. And then the device >> paramters are configured. Where for us, we configure the device parameter >> first, and then create the mdev. But in the end, it's still the hybrid mdev >> setup right? > So you don't even use mdev to configure anything? Yuk. > > Jason
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