From: Bjorn Helgaas <helgaas@kernel.org>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Yishai Hadas <yishaih@nvidia.com>,
bhelgaas@google.com, corbet@lwn.net, alex.williamson@redhat.com,
diana.craciun@oss.nxp.com, kwankhede@nvidia.com,
eric.auger@redhat.com, masahiroy@kernel.org,
michal.lkml@markovi.net, linux-pci@vger.kernel.org,
linux-doc@vger.kernel.org, kvm@vger.kernel.org,
linux-s390@vger.kernel.org, linux-kbuild@vger.kernel.org,
mgurtovoy@nvidia.com, maorg@nvidia.com, leonro@nvidia.com
Subject: Re: [PATCH 09/12] PCI: Add a PCI_ID_F_VFIO_DRIVER_OVERRIDE flag to struct pci_device_id
Date: Thu, 12 Aug 2021 15:26:32 -0500 [thread overview]
Message-ID: <20210812202632.GA2504075@bjorn-Precision-5520> (raw)
In-Reply-To: <20210812195126.GA4026@nvidia.com>
On Thu, Aug 12, 2021 at 04:51:26PM -0300, Jason Gunthorpe wrote:
> On Thu, Aug 12, 2021 at 10:57:07AM -0500, Bjorn Helgaas wrote:
> > On Thu, Aug 12, 2021 at 10:27:28AM -0300, Jason Gunthorpe wrote:
> > > On Wed, Aug 11, 2021 at 02:07:37PM -0500, Bjorn Helgaas wrote:
> > > > On Thu, Aug 05, 2021 at 09:23:57PM -0300, Jason Gunthorpe wrote:
> >
> > > > Do the other bus types have a flag analogous to
> > > > PCI_ID_F_VFIO_DRIVER_OVERRIDE? If we're doing something similar to
> > > > other bus types, it'd be nice if the approach were similar.
> > >
> > > They could, this series doesn't attempt it. I expect the approach to
> > > be similar as driver_override was copied from PCI to other
> > > busses. When this is completed I hope to take a look at it.
> >
> > I think this would make more sense as two patches:
> >
> > - Add a "PCI_ID_DRIVER_OVERRIDE" flag. This is not VFIO-specific,
> > since nothing in PCI depends on the VFIO-ness of drivers that use
> > the flag. The only point here is that driver id_table entries
> > with this flag only match when driver_override matches the driver.
>
> This would require using two flags, one to indicate the above to the
> PCI code and another to indicate the vfio_pci string to
> file2alias. This doesn't seem justified at this point, IMHO.
I don't think it requires two flags. do_pci_entry() has:
if (flags & PCI_ID_F_VFIO_DRIVER_OVERRIDE)
strcpy(alias, "vfio_pci:");
I'm just proposing a rename:
s/PCI_ID_F_VFIO_DRIVER_OVERRIDE/PCI_ID_DRIVER_OVERRIDE/
> > - Update file2alias.c to export the flags and the "vfio_pci:" alias.
> > This seems to be the only place where VFIO comes into play, and
> > putting it in a separate patch will make it much smaller and it
> > will be clear how it could be extended for other buses.
>
> Well, I don't want to see a flag called PCI_ID_DRIVER_OVERRIDE mapped
> to the string "vfio_pci", that is just really confusing.
Hahaha, I see, that's fair :) It confused me for a long time why you
wanted "VFIO" in the flag name because from the kernel's point of
view, the flag is not related to any VFIO-ness. It's only related to
a special variety of driver_override, and VFIO happens to be one user
of it.
I think a separate patch that maps the flag to "vfio_pci" would be
less confusing because without the distractions of the PCI core
changes, it will be obvious that "vfio_" is a file2alias thing that's
there for userspace convenience, not for kernel reasons.
Do you envision any other prefixes in the future? I hope we don't
have to clutter pci_match_device() with checking multiple flags.
Maybe the problem is that the modules.alias entry includes "vfio_" --
maybe we need a more generic prefix with just the idea of an
"alternate" driver.
Bjorn
next prev parent reply other threads:[~2021-08-12 20:26 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-21 16:15 [PATCH 00/12] Introduce vfio_pci_core subsystem Yishai Hadas
2021-07-21 16:15 ` [PATCH 01/12] vfio/pci: Rename vfio_pci.c to vfio_pci_core.c Yishai Hadas
2021-07-21 16:15 ` [PATCH 02/12] vfio/pci: Rename vfio_pci_private.h to vfio_pci_core.h Yishai Hadas
2021-07-21 16:16 ` [PATCH 03/12] vfio/pci: Rename vfio_pci_device to vfio_pci_core_device Yishai Hadas
2021-07-21 16:16 ` [PATCH 04/12] vfio/pci: Rename ops functions to fit core namings Yishai Hadas
2021-07-21 16:16 ` [PATCH 05/12] vfio/pci: Include vfio header in vfio_pci_core.h Yishai Hadas
2021-07-21 16:16 ` [PATCH 06/12] vfio/pci: Split the pci_driver code out of vfio_pci_core.c Yishai Hadas
2021-07-21 16:16 ` [PATCH 07/12] vfio/pci: Move igd initialization to vfio_pci.c Yishai Hadas
2021-07-21 16:16 ` [PATCH 08/12] vfio/pci: Move module parameters " Yishai Hadas
2021-07-21 16:16 ` [PATCH 09/12] PCI: Add a PCI_ID_F_VFIO_DRIVER_OVERRIDE flag to struct pci_device_id Yishai Hadas
2021-07-27 16:34 ` Alex Williamson
2021-07-27 17:14 ` Jason Gunthorpe
2021-07-27 23:02 ` Alex Williamson
2021-07-27 23:42 ` Jason Gunthorpe
2021-08-04 20:34 ` Bjorn Helgaas
2021-08-05 16:47 ` Max Gurtovoy
2021-08-06 0:23 ` Jason Gunthorpe
2021-08-11 12:22 ` Max Gurtovoy
2021-08-11 19:07 ` Bjorn Helgaas
2021-08-12 13:27 ` Jason Gunthorpe
2021-08-12 15:57 ` Bjorn Helgaas
2021-08-12 19:51 ` Jason Gunthorpe
2021-08-12 20:26 ` Bjorn Helgaas [this message]
2021-08-12 23:21 ` Max Gurtovoy
2021-08-13 17:44 ` Bjorn Helgaas
2021-08-14 23:27 ` Max Gurtovoy
2021-08-16 17:21 ` Bjorn Helgaas
2021-08-17 13:01 ` Max Gurtovoy
2021-08-17 14:13 ` Bjorn Helgaas
2021-08-17 14:44 ` Max Gurtovoy
2021-08-12 15:42 ` Bjorn Helgaas
2021-07-21 16:16 ` [PATCH 10/12] vfio: Use select for eventfd Yishai Hadas
2021-07-21 16:16 ` [PATCH 11/12] vfio: Use kconfig if XX/endif blocks instead of repeating 'depends on' Yishai Hadas
2021-07-21 16:16 ` [PATCH 12/12] vfio/pci: Introduce vfio_pci_core.ko Yishai Hadas
2021-07-21 17:39 ` Leon Romanovsky
2021-07-22 9:06 ` Yishai Hadas
2021-07-22 9:22 ` Max Gurtovoy
2021-07-23 14:13 ` Leon Romanovsky
2021-07-25 10:45 ` Max Gurtovoy
2021-07-27 21:54 ` Alex Williamson
2021-07-27 23:09 ` Jason Gunthorpe
2021-07-28 4:56 ` Leon Romanovsky
2021-07-28 5:43 ` Christoph Hellwig
2021-07-28 7:04 ` Arnd Bergmann
2021-07-28 7:17 ` Leon Romanovsky
2021-07-28 12:03 ` Jason Gunthorpe
2021-07-28 12:12 ` Arnd Bergmann
2021-07-28 12:29 ` Christoph Hellwig
2021-07-28 12:47 ` Jason Gunthorpe
2021-07-28 12:55 ` Christoph Hellwig
2021-07-28 13:31 ` Jason Gunthorpe
2021-07-28 13:08 ` Arnd Bergmann
2021-07-28 17:26 ` Jason Gunthorpe
2021-08-04 13:41 ` [PATCH 00/12] Introduce vfio_pci_core subsystem Yishai Hadas
2021-08-04 15:27 ` Alex Williamson
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