Re: [PATCH v2 09/13] vfio/mdev: Remove vfio_mdev.c

From: Jason Gunthorpe <jgg@nvidia.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Christoph Hellwig <hch@lst.de>,
	Alex Williamson <alex.williamson@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>,
	kvm@vger.kernel.org, Kirti Wankhede <kwankhede@nvidia.com>,
	linux-doc@vger.kernel.org, "Raj, Ashok" <ashok.raj@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Daniel Vetter <daniel@ffwll.ch>,
	Leon Romanovsky <leonro@nvidia.com>,
	Max Gurtovoy <mgurtovoy@nvidia.com>,
	Tarun Gupta <targupta@nvidia.com>
Subject: Re: [PATCH v2 09/13] vfio/mdev: Remove vfio_mdev.c
Date: Wed, 28 Apr 2021 09:53:21 -0300	[thread overview]
Message-ID: <20210428125321.GP1370958@nvidia.com> (raw)
In-Reply-To: <YIkCVnTFmTHiX3xn@kroah.com>

On Wed, Apr 28, 2021 at 08:36:06AM +0200, Greg Kroah-Hartman wrote:
> On Wed, Apr 28, 2021 at 08:07:03AM +0200, Christoph Hellwig wrote:
> > On Mon, Apr 26, 2021 at 05:00:11PM -0300, Jason Gunthorpe wrote:
> > > Preserve VFIO's design of allowing mdev drivers to be !GPL by allowing the
> > > three functions that replace this module for !GPL usage. This goes along
> > > with the other 19 symbols that are already marked !GPL in VFIO.
> > 
> > NAK.  This was a sneak by Nvidia to try a GPL condom, and now that we
> > remove that not working condom it does not mean core symbols can be
> > just changed.
> 
> Agreed, these symbols should not be changed.

During the development on this series I got a private email that
people have existing !GPL mdev drivers.

When I checked I saw that VFIO community seems to have decided that
!GPL is OK for mdev. I say this because many essential symbols for
implementing a mdev in vfio.c have been marked !GPL:

drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_info_cap_shift);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_info_add_capability);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_set_irqs_validate_and_prepare);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_pin_pages);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_unpin_pages);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_group_pin_pages);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_group_unpin_pages);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_dma_rw);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_register_notifier);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_unregister_notifier);

Why it is like this, I do not know. IMHO it is not some "condom" if a
chunk of the core vfio.c code is marked !GPL and is called by mdev
drivers.

The Linux standard is one patch one change. It is inapporiate for me
to backdoor sneak revert the VFIO communities past decisions on
licensing inside some unrelated cleanup patch.

If you two want to argue VFIO has err'd and should be using GPL for
its API toward mdev then please send a patch to switch the above
symbols and I'll rebase this series ontop of it.

That way the change can get a proper airing and not be sneakily buried
inside a cleanup patch.

Otherwise this patch changes nothing - what existed today continues to
exist, and nothing new is being allowed.

Jason