On Wed, Feb 08, 2023 at 04:25:58AM +0000, Tian, Kevin wrote:
From: Jason Gunthorpe jgg@nvidia.com Sent: Tuesday, February 7, 2023 8:23 PM
On Tue, Feb 07, 2023 at 12:32:50AM +0000, Tian, Kevin wrote:
From: Jason Gunthorpe jgg@nvidia.com Sent: Monday, February 6, 2023 9:25 PM
On Mon, Feb 06, 2023 at 06:57:35AM +0000, Tian, Kevin wrote:
From: Jason Gunthorpe jgg@nvidia.com Sent: Friday, February 3, 2023 11:03 PM
On Fri, Feb 03, 2023 at 08:26:44AM +0000, Tian, Kevin wrote: > > From: Nicolin Chen nicolinc@nvidia.com > > Sent: Thursday, February 2, 2023 3:05 PM > > > > All drivers are already required to support changing between
active
> > UNMANAGED domains when using their attach_dev ops. > > All drivers which don't have *broken* UNMANAGED domain?
No, all drivers.. It has always been used by VFIO.
existing iommu_attach_group() doesn't support changing between two UNMANAGED domains. only from default->unmanaged or blocking->unmanaged.
Yes, but before we added the blocking domains VFIO was changing between unmanaged domains. Blocking domains are so new that no
driver
could have suddenly started to depend on this.
In legacy VFIO unmanaged domain was 1:1 associated with vfio container. I didn't say how a group can switch between two containers w/o going through transition to/from the default domain, i.e. detach from 1st container and then attach to the 2nd.
Yes, in the past we went through the default domain which is basically another unmanaged domain type. So unmanaged -> unmanaged is OK.
it's right in concept but confusing in current context whether DMA domain still has its own type. That's why I replied earlier the statement makes more sense after your patch which cleans up the domain type is merged.
We are just reasoning about why the existing drivers are safe with this - and my draft patch to remove DMA simply demonstrates that DMA == UNMANAGED, and the above reasoning about VFIO in the past demonstrates that this has historically be expected of drivers.
So I'm not so worried about patch order as long as things do work
Jason