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From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	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 17:35:15 -0300	[thread overview]
Message-ID: <20210615203515.GW1002214@nvidia.com> (raw)
In-Reply-To: <20210615133549.362e5a9e.alex.williamson@redhat.com>

On Tue, Jun 15, 2021 at 01:35:49PM -0600, Alex Williamson wrote:
> 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.

I have those updates in the patch that removes the old way, do you
want to move them forward to here?

> Also, if we're preserving compatibility with the "legacy"
> mdev_parent_ops callbacks without deprecating them,

I view this as breaking up the work into manageable steps and patch
series. This is already at 10 patches just to provide the
infrastructure. The next steps will be to move the driver conversions
ahead.

> does it really make sense to convert every one of the sample drivers
> to this new direct registration?  

Yes, the rest of the drivers will get converted eventually too. There
is no reason to hold things back. Depending on timelines we might be
able to get AP into this cycle too...

Jason

WARNING: multiple messages have this Message-ID
From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>
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>,
	Christoph Hellwig <hch@lst.de>,
	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>,
	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 17:35:15 -0300	[thread overview]
Message-ID: <20210615203515.GW1002214@nvidia.com> (raw)
In-Reply-To: <20210615133549.362e5a9e.alex.williamson@redhat.com>

On Tue, Jun 15, 2021 at 01:35:49PM -0600, Alex Williamson wrote:
> 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.

I have those updates in the patch that removes the old way, do you
want to move them forward to here?

> Also, if we're preserving compatibility with the "legacy"
> mdev_parent_ops callbacks without deprecating them,

I view this as breaking up the work into manageable steps and patch
series. This is already at 10 patches just to provide the
infrastructure. The next steps will be to move the driver conversions
ahead.

> does it really make sense to convert every one of the sample drivers
> to this new direct registration?  

Yes, the rest of the drivers will get converted eventually too. There
is no reason to hold things back. Depending on timelines we might be
able to get AP into this cycle too...

Jason

WARNING: multiple messages have this Message-ID
From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>
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>,
	Christoph Hellwig <hch@lst.de>,
	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>,
	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 17:35:15 -0300	[thread overview]
Message-ID: <20210615203515.GW1002214@nvidia.com> (raw)
In-Reply-To: <20210615133549.362e5a9e.alex.williamson@redhat.com>

On Tue, Jun 15, 2021 at 01:35:49PM -0600, Alex Williamson wrote:
> 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.

I have those updates in the patch that removes the old way, do you
want to move them forward to here?

> Also, if we're preserving compatibility with the "legacy"
> mdev_parent_ops callbacks without deprecating them,

I view this as breaking up the work into manageable steps and patch
series. This is already at 10 patches just to provide the
infrastructure. The next steps will be to move the driver conversions
ahead.

> does it really make sense to convert every one of the sample drivers
> to this new direct registration?  

Yes, the rest of the drivers will get converted eventually too. There
is no reason to hold things back. Depending on timelines we might be
able to get AP into this cycle too...

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

  reply	other threads:[~2021-06-15 20:35 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 ` Allow mdev drivers to directly create the vfio_device (v3) Alex Williamson
2021-06-15 19:35   ` [Intel-gfx] " Alex Williamson
2021-06-15 19:35   ` Alex Williamson
2021-06-15 20:35   ` Jason Gunthorpe [this message]
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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