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From: Alex Williamson <alex.williamson@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Kirti Wankhede <kwankhede@nvidia.com>,
	David Airlie <airlied@linux.ie>,
	Tony Krowiak <akrowiak@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>, Daniel Vetter <daniel@ffwll.ch>,
	dri-devel@lists.freedesktop.org,
	Vasily Gorbik <gor@linux.ibm.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	intel-gfx@lists.freedesktop.org,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Jason Herne <jjherne@linux.ibm.com>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	kvm@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-s390@vger.kernel.org, Halil Pasic <pasic@linux.ibm.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>
Subject: Re: Allow mdev drivers to directly create the vfio_device (v3)
Date: Tue, 15 Jun 2021 13:35:49 -0600	[thread overview]
Message-ID: <20210615133549.362e5a9e.alex.williamson@redhat.com> (raw)
In-Reply-To: <20210615133519.754763-1-hch@lst.de>

On Tue, 15 Jun 2021 15:35:09 +0200
Christoph Hellwig <hch@lst.de> wrote:

> This is my alternative take on this series from Jason:
> 
> https://lore.kernel.org/dri-devel/87czsszi9i.fsf@redhat.com/T/
> 
> The mdev/vfio parts are exactly the same, but this solves the driver core
> changes for the direct probing without the in/out flag that Greg hated,
> which cause a little more work, but probably make the result better.
> 
> Original decription from Jason below:
> 
> The mdev bus's core part for managing the lifecycle of devices is mostly
> as one would expect for a driver core bus subsystem.
> 
> However instead of having a normal 'struct device_driver' and binding the
> actual mdev drivers through the standard driver core mechanisms it open
> codes this with the struct mdev_parent_ops and provides a single driver
> that shims between the VFIO core's struct vfio_device and the actual
> device driver.
> 
> Instead, allow mdev drivers implement an actual struct mdev_driver and
> directly call vfio_register_group_dev() in the probe() function for the
> mdev. Arrange to bind the created mdev_device to the mdev_driver that is
> provided by the end driver.
> 
> The actual execution flow doesn't change much, eg what was
> parent_ops->create is now device_driver->probe and it is called at almost
> the exact same time - except under the normal control of the driver core.
> 
> Ultimately converting all the drivers unlocks a fair number of additional
> VFIO simplifications and cleanups.

Looks like we need an update to
Documentation/driver-api/vfio-mediated-device.rst to go along with
this.

Also, if we're preserving compatibility with the "legacy"
mdev_parent_ops callbacks without deprecating them, does it really make
sense to convert every one of the sample drivers to this new direct
registration?  Thanks,

Alex


WARNING: multiple messages have this Message-ID
From: Alex Williamson <alex.williamson@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: kvm@vger.kernel.org, linux-doc@vger.kernel.org,
	David Airlie <airlied@linux.ie>,
	dri-devel@lists.freedesktop.org,
	Kirti Wankhede <kwankhede@nvidia.com>,
	linux-s390@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Halil Pasic <pasic@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Jason Gunthorpe <jgg@nvidia.com>,
	intel-gfx@lists.freedesktop.org,
	Jason Herne <jjherne@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	Tony Krowiak <akrowiak@linux.ibm.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Cornelia Huck <cohuck@redhat.com>
Subject: Re: Allow mdev drivers to directly create the vfio_device (v3)
Date: Tue, 15 Jun 2021 13:35:49 -0600	[thread overview]
Message-ID: <20210615133549.362e5a9e.alex.williamson@redhat.com> (raw)
In-Reply-To: <20210615133519.754763-1-hch@lst.de>

On Tue, 15 Jun 2021 15:35:09 +0200
Christoph Hellwig <hch@lst.de> wrote:

> This is my alternative take on this series from Jason:
> 
> https://lore.kernel.org/dri-devel/87czsszi9i.fsf@redhat.com/T/
> 
> The mdev/vfio parts are exactly the same, but this solves the driver core
> changes for the direct probing without the in/out flag that Greg hated,
> which cause a little more work, but probably make the result better.
> 
> Original decription from Jason below:
> 
> The mdev bus's core part for managing the lifecycle of devices is mostly
> as one would expect for a driver core bus subsystem.
> 
> However instead of having a normal 'struct device_driver' and binding the
> actual mdev drivers through the standard driver core mechanisms it open
> codes this with the struct mdev_parent_ops and provides a single driver
> that shims between the VFIO core's struct vfio_device and the actual
> device driver.
> 
> Instead, allow mdev drivers implement an actual struct mdev_driver and
> directly call vfio_register_group_dev() in the probe() function for the
> mdev. Arrange to bind the created mdev_device to the mdev_driver that is
> provided by the end driver.
> 
> The actual execution flow doesn't change much, eg what was
> parent_ops->create is now device_driver->probe and it is called at almost
> the exact same time - except under the normal control of the driver core.
> 
> Ultimately converting all the drivers unlocks a fair number of additional
> VFIO simplifications and cleanups.

Looks like we need an update to
Documentation/driver-api/vfio-mediated-device.rst to go along with
this.

Also, if we're preserving compatibility with the "legacy"
mdev_parent_ops callbacks without deprecating them, does it really make
sense to convert every one of the sample drivers to this new direct
registration?  Thanks,

Alex


WARNING: multiple messages have this Message-ID
From: Alex Williamson <alex.williamson@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: kvm@vger.kernel.org, linux-doc@vger.kernel.org,
	David Airlie <airlied@linux.ie>,
	dri-devel@lists.freedesktop.org,
	Kirti Wankhede <kwankhede@nvidia.com>,
	linux-s390@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Halil Pasic <pasic@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Jason Gunthorpe <jgg@nvidia.com>,
	intel-gfx@lists.freedesktop.org,
	Jason Herne <jjherne@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	Tony Krowiak <akrowiak@linux.ibm.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Cornelia Huck <cohuck@redhat.com>
Subject: Re: [Intel-gfx] Allow mdev drivers to directly create the vfio_device (v3)
Date: Tue, 15 Jun 2021 13:35:49 -0600	[thread overview]
Message-ID: <20210615133549.362e5a9e.alex.williamson@redhat.com> (raw)
In-Reply-To: <20210615133519.754763-1-hch@lst.de>

On Tue, 15 Jun 2021 15:35:09 +0200
Christoph Hellwig <hch@lst.de> wrote:

> This is my alternative take on this series from Jason:
> 
> https://lore.kernel.org/dri-devel/87czsszi9i.fsf@redhat.com/T/
> 
> The mdev/vfio parts are exactly the same, but this solves the driver core
> changes for the direct probing without the in/out flag that Greg hated,
> which cause a little more work, but probably make the result better.
> 
> Original decription from Jason below:
> 
> The mdev bus's core part for managing the lifecycle of devices is mostly
> as one would expect for a driver core bus subsystem.
> 
> However instead of having a normal 'struct device_driver' and binding the
> actual mdev drivers through the standard driver core mechanisms it open
> codes this with the struct mdev_parent_ops and provides a single driver
> that shims between the VFIO core's struct vfio_device and the actual
> device driver.
> 
> Instead, allow mdev drivers implement an actual struct mdev_driver and
> directly call vfio_register_group_dev() in the probe() function for the
> mdev. Arrange to bind the created mdev_device to the mdev_driver that is
> provided by the end driver.
> 
> The actual execution flow doesn't change much, eg what was
> parent_ops->create is now device_driver->probe and it is called at almost
> the exact same time - except under the normal control of the driver core.
> 
> Ultimately converting all the drivers unlocks a fair number of additional
> VFIO simplifications and cleanups.

Looks like we need an update to
Documentation/driver-api/vfio-mediated-device.rst to go along with
this.

Also, if we're preserving compatibility with the "legacy"
mdev_parent_ops callbacks without deprecating them, does it really make
sense to convert every one of the sample drivers to this new direct
registration?  Thanks,

Alex

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

  parent reply	other threads:[~2021-06-15 19:35 UTC|newest]

Thread overview: 90+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-15 13:35 Christoph Hellwig
2021-06-15 13:35 ` [Intel-gfx] " Christoph Hellwig
2021-06-15 13:35 ` [PATCH 01/10] driver core: Pull required checks into driver_probe_device() Christoph Hellwig
2021-06-15 13:35   ` [Intel-gfx] " Christoph Hellwig
2021-06-15 13:35 ` [PATCH 02/10] driver core: Better distinguish probe errors in really_probe Christoph Hellwig
2021-06-15 13:35   ` [Intel-gfx] " Christoph Hellwig
2021-06-15 13:53   ` Cornelia Huck
2021-06-15 13:53     ` [Intel-gfx] " Cornelia Huck
2021-06-15 13:53     ` Cornelia Huck
2021-06-15 14:09     ` Greg Kroah-Hartman
2021-06-15 14:09       ` [Intel-gfx] " Greg Kroah-Hartman
2021-06-15 14:09       ` Greg Kroah-Hartman
2021-06-15 14:09   ` Greg Kroah-Hartman
2021-06-15 14:09     ` [Intel-gfx] " Greg Kroah-Hartman
2021-06-15 14:09     ` Greg Kroah-Hartman
2021-06-16 20:20   ` Kirti Wankhede
2021-06-16 20:20     ` [Intel-gfx] " Kirti Wankhede
2021-06-16 20:20     ` Kirti Wankhede
2021-06-15 13:35 ` [PATCH 03/10] driver core: Flow the return code from ->probe() through to sysfs bind Christoph Hellwig
2021-06-15 13:35   ` [Intel-gfx] " Christoph Hellwig
2021-06-15 13:35 ` [PATCH 04/10] driver core: Don't return EPROBE_DEFER to userspace during " Christoph Hellwig
2021-06-15 13:35   ` [Intel-gfx] " Christoph Hellwig
2021-06-15 14:03   ` Cornelia Huck
2021-06-15 14:03     ` [Intel-gfx] " Cornelia Huck
2021-06-15 14:03     ` Cornelia Huck
2021-06-15 19:36   ` Alex Williamson
2021-06-15 19:36     ` [Intel-gfx] " Alex Williamson
2021-06-15 19:36     ` Alex Williamson
2021-06-15 13:35 ` [PATCH 05/10] driver core: Export device_driver_attach() Christoph Hellwig
2021-06-15 13:35   ` [Intel-gfx] " Christoph Hellwig
2021-06-15 14:10   ` Greg Kroah-Hartman
2021-06-15 14:10     ` [Intel-gfx] " Greg Kroah-Hartman
2021-06-15 14:10     ` Greg Kroah-Hartman
2021-06-15 13:35 ` [PATCH 06/10] vfio/mdev: Remove CONFIG_VFIO_MDEV_DEVICE Christoph Hellwig
2021-06-15 13:35   ` [Intel-gfx] " Christoph Hellwig
2021-06-15 14:10   ` Greg Kroah-Hartman
2021-06-15 14:10     ` [Intel-gfx] " Greg Kroah-Hartman
2021-06-15 14:10     ` Greg Kroah-Hartman
2021-06-16 20:20   ` Kirti Wankhede
2021-06-16 20:20     ` [Intel-gfx] " Kirti Wankhede
2021-06-16 20:20     ` Kirti Wankhede
2021-06-15 13:35 ` [PATCH 07/10] vfio/mdev: Allow the mdev_parent_ops to specify the device driver to bind Christoph Hellwig
2021-06-15 13:35   ` [Intel-gfx] " Christoph Hellwig
2021-06-15 14:06   ` Cornelia Huck
2021-06-15 14:06     ` [Intel-gfx] " Cornelia Huck
2021-06-15 14:06     ` Cornelia Huck
2021-06-15 14:11   ` Greg Kroah-Hartman
2021-06-15 14:11     ` [Intel-gfx] " Greg Kroah-Hartman
2021-06-15 14:11     ` Greg Kroah-Hartman
2021-06-16  0:00     ` Jason Gunthorpe
2021-06-16  0:00       ` [Intel-gfx] " Jason Gunthorpe
2021-06-16  0:00       ` Jason Gunthorpe
2021-06-16  6:39       ` Greg Kroah-Hartman
2021-06-16  6:39         ` [Intel-gfx] " Greg Kroah-Hartman
2021-06-16  6:39         ` Greg Kroah-Hartman
2021-06-16 20:20   ` Kirti Wankhede
2021-06-16 20:20     ` [Intel-gfx] " Kirti Wankhede
2021-06-16 20:20     ` Kirti Wankhede
2021-06-15 13:35 ` [PATCH 08/10] vfio/mtty: Convert to use vfio_register_group_dev() Christoph Hellwig
2021-06-15 13:35   ` [Intel-gfx] " Christoph Hellwig
2021-06-15 14:11   ` Greg Kroah-Hartman
2021-06-15 14:11     ` [Intel-gfx] " Greg Kroah-Hartman
2021-06-15 14:11     ` Greg Kroah-Hartman
2021-06-16 20:20   ` Kirti Wankhede
2021-06-16 20:20     ` [Intel-gfx] " Kirti Wankhede
2021-06-16 20:20     ` Kirti Wankhede
2021-06-15 13:35 ` [PATCH 09/10] vfio/mdpy: " Christoph Hellwig
2021-06-15 13:35   ` [Intel-gfx] " Christoph Hellwig
2021-06-15 14:12   ` Greg Kroah-Hartman
2021-06-15 14:12     ` [Intel-gfx] " Greg Kroah-Hartman
2021-06-15 14:12     ` Greg Kroah-Hartman
2021-06-15 13:35 ` [PATCH 10/10] vfio/mbochs: " Christoph Hellwig
2021-06-15 13:35   ` [Intel-gfx] " Christoph Hellwig
2021-06-15 14:12   ` Greg Kroah-Hartman
2021-06-15 14:12     ` [Intel-gfx] " Greg Kroah-Hartman
2021-06-15 14:12     ` Greg Kroah-Hartman
2021-06-15 14:11 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for series starting with [01/10] driver core: Pull required checks into driver_probe_device() Patchwork
2021-06-15 14:15 ` [Intel-gfx] ✗ Fi.CI.SPARSE: " Patchwork
2021-06-15 14:40 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2021-06-15 19:35 ` Alex Williamson [this message]
2021-06-15 19:35   ` [Intel-gfx] Allow mdev drivers to directly create the vfio_device (v3) Alex Williamson
2021-06-15 19:35   ` Alex Williamson
2021-06-15 20:35   ` Jason Gunthorpe
2021-06-15 20:35     ` [Intel-gfx] " Jason Gunthorpe
2021-06-15 20:35     ` Jason Gunthorpe
2021-06-16  3:13     ` Christoph Hellwig
2021-06-16  3:13       ` [Intel-gfx] " Christoph Hellwig
2021-06-16 14:03       ` Jason Gunthorpe
2021-06-16 14:03         ` Jason Gunthorpe
2021-06-15 21:59 ` [Intel-gfx] ✓ Fi.CI.IGT: success for series starting with [01/10] driver core: Pull required checks into driver_probe_device() Patchwork

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