> From: Jason Gunthorpe <jgg@xxxxxxxxxx> > Sent: Thursday, June 3, 2021 7:18 AM > > On Wed, Jun 02, 2021 at 08:40:51AM -0700, Dave Jiang wrote: > > > > On 5/23/2021 4:22 PM, Jason Gunthorpe wrote: > > > On Fri, May 21, 2021 at 05:19:05PM -0700, Dave Jiang wrote: > > > > Introducing mdev types “1dwq-v1” type. This mdev type allows > > > > allocation of a single dedicated wq from available dedicated wqs. After > > > > a workqueue (wq) is enabled, the user will generate an uuid. On mdev > > > > creation, the mdev driver code will find a dwq depending on the mdev > > > > type. When the create operation is successful, the user generated uuid > > > > can be passed to qemu. When the guest boots up, it should discover a > > > > DSA device when doing PCI discovery. > > > > > > > > For example of “1dwq-v1” type: > > > > 1. Enable wq with “mdev” wq type > > > > 2. A user generated uuid. > > > > 3. The uuid is written to the mdev class sysfs path: > > > > echo $UUID > > /sys/class/mdev_bus/0000\:00\:0a.0/mdev_supported_types/idxd-1dwq- > v1/create > > > > 4. Pass the following parameter to qemu: > > > > "-device vfio-pci,sysfsdev=/sys/bus/pci/devices/0000:00:0a.0/$UUID" > > > So the idxd core driver knows to create a "vfio" wq with its own much > > > machinery but you still want to involve the horrible mdev guid stuff? > > > > > > Why?? > > > > Are you referring to calling mdev_device_create() directly in the mdev > > idxd_driver probe? > > No, just call vfio_register_group_dev and forget about mdev. > > > I think this would work with our dedicated wq where a single mdev > > can be assigned to a wq. > > Ok, sounds great > > > However, later on when we need to support shared wq where we can > > create multiple mdev per wq, we'll need an entry point to do so. In > > the name of making things consistent from user perspective, going > > through sysfs seems the way to do it. > > Why not use your already very complicated idxd sysfs to do this? > Jason, can you clarify your attitude on mdev guid stuff? Are you completely against it or case-by-case? If the former, this is a big decision thus it's better to have consensus with Alex/Kirti. If the latter, would like to hear your criteria for when it can be used and when not... Thanks Kevin
