Re: [PATCH RFC 07/19] iommufd/vfio-compat: Dirty tracking IOCTLs compatibility

Jason Gunthorpe
2022-04-29T14:37:29Z

On Fri, Apr 29, 2022 at 03:27:00PM +0100, Joao Martins wrote:

> > We've made a qemu patch to allow qemu to be happy if dirty tracking is
> > not supported in the vfio container for migration, which is part of
> > the v2 enablement series. That seems like the better direction.
> >
> So in my auditing/testing, the listener callbacks are called but the dirty ioctls
> return an error at start, and bails out early on sync. I suppose migration
> won't really work, as no pages aren't set and what not but it could
> cope with no-dirty-tracking support. So by 'making qemu happy' is this mainly
> cleaning out the constant error messages you get and not even attempt
> migration by introducing a migration blocker early on ... should it fetch
> no migration capability?

It really just means pre-copy doesn't work and we can skip it, though
I'm not sure exactly what the qemu patch ended up doing.. I think it
will be posted by Monday

Jason