From: Cornelia Huck <cohuck@redhat.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>, Christoph Hellwig <hch@lst.de>,
Max Gurtovoy <mgurtovoy@nvidia.com>,
Alexey Kardashevskiy <aik@ozlabs.ru>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
liranl@nvidia.com, oren@nvidia.com, tzahio@nvidia.com,
leonro@nvidia.com, yarong@nvidia.com, aviadye@nvidia.com,
shahafs@nvidia.com, artemp@nvidia.com, kwankhede@nvidia.com,
ACurrid@nvidia.com, cjia@nvidia.com, yishaih@nvidia.com,
mjrosato@linux.ibm.com
Subject: Re: [PATCH 8/9] vfio/pci: export nvlink2 support into vendor vfio_pci drivers
Date: Thu, 1 Apr 2021 15:04:45 +0200 [thread overview]
Message-ID: <20210401150445.70dc025f.cohuck@redhat.com> (raw)
In-Reply-To: <20210329171053.7a2ebce3@omen.home.shazbot.org>
On Mon, 29 Mar 2021 17:10:53 -0600
Alex Williamson <alex.williamson@redhat.com> wrote:
> On Tue, 23 Mar 2021 16:32:13 -0300
> Jason Gunthorpe <jgg@nvidia.com> wrote:
>
> > On Mon, Mar 22, 2021 at 10:40:16AM -0600, Alex Williamson wrote:
> > > So unless you want to do some bitkeeper archaeology, we've always
> > > allowed driver probes to fail and fall through to the next one, not
> > > even complaining with -ENODEV. In practice it hasn't been an issue
> > > because how many drivers do you expect to have that would even try to
> > > claim a device.
> >
> > Do you know of anything using this ability? It might be helpful
>
> I don't.
I've been trying to remember why I added that patch to ignore all
errors (rather than only -ENODEV), but I suspect it might have been
related to the concurrent probing stuff I tried to implement back then.
The one instance of drivers matching to the same id I recall (s390
ctc/lcs) is actually not handled on the individual device level, but in
the meta ccwgroup driver; I don't remember anything else in the s390
case.
>
> > > Ordering is only important when there's a catch-all so we need to
> > > figure out how to make that last among a class of drivers that will
> > > attempt to claim a device. The softdep is a bit of a hack to do
> > > that, I'll admit, but I don't see how the alternate driver flavor
> > > universe solves having a catch-all either.
> >
> > Haven't entirely got there yet, but I think the catch all probably has
> > to be handled by userspace udev/kmod in some way, as it is the only
> > thing that knows if there is a more specific module to load. This is
> > the biggest problem..
> >
> > And again, I feel this is all a big tangent, especially now that HCH
> > wants to delete the nvlink stuff we should just leave igd alone.
>
> Determining which things stay in vfio-pci-core and which things are
> split to variant drivers and how those variant drivers can match the
> devices they intend to support seems very inline with this series. If
> igd stays as part of vfio-pci-core then I think we're drawing a
> parallel to z-pci support, where a significant part of that support is
> a set of extra data structures exposed through capabilities to support
> userspace use of the device. Therefore extra regions or data
> structures through capabilities, where we're not changing device
> access, except as required for the platform (not the device) seem to be
> things that fit within the core, right? Thanks,
>
> Alex
As we are only talking about extra data governed by a capability, I
don't really see a problem with keeping it in the vfio core.
For those devices that need more specialized treatment, maybe we need
some kind of priority-based matching? I.e., if we match a device with
drivers, start with the one with highest priority (the specialized
one), and have the generic driver at the lowest priority. A
higher-priority driver added later one should not affect already bound
devices (and would need manual intervention again.)
[I think this has come up in other places in the past as well, but I
don't have any concrete pointers handy.]
next prev parent reply other threads:[~2021-04-01 18:12 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-09 8:33 [PATCH v3 0/9] Introduce vfio-pci-core subsystem Max Gurtovoy
2021-03-09 8:33 ` [PATCH 1/9] vfio-pci: rename vfio_pci.c to vfio_pci_core.c Max Gurtovoy
2021-03-09 8:33 ` [PATCH 2/9] vfio-pci: rename vfio_pci_private.h to vfio_pci_core.h Max Gurtovoy
2021-03-09 8:33 ` [PATCH 3/9] vfio-pci: rename vfio_pci_device to vfio_pci_core_device Max Gurtovoy
2021-03-09 8:33 ` [PATCH 4/9] vfio-pci: introduce vfio_pci_core subsystem driver Max Gurtovoy
2021-03-09 8:33 ` [PATCH 5/9] vfio/pci: introduce vfio_pci_device structure Max Gurtovoy
2021-03-09 8:33 ` [PATCH 6/9] vfio-pci-core: export vfio_pci_register_dev_region function Max Gurtovoy
2021-03-09 8:33 ` [PATCH 7/9] vfio/pci_core: split nvlink2 to nvlink2gpu and npu2 Max Gurtovoy
2021-03-10 8:08 ` Christoph Hellwig
2021-03-09 8:33 ` [PATCH 8/9] vfio/pci: export nvlink2 support into vendor vfio_pci drivers Max Gurtovoy
2021-03-10 6:39 ` Alexey Kardashevskiy
2021-03-10 12:57 ` Max Gurtovoy
2021-03-10 13:02 ` Jason Gunthorpe
2021-03-10 14:24 ` Alexey Kardashevskiy
2021-03-10 19:40 ` Jason Gunthorpe
2021-03-11 1:20 ` Alexey Kardashevskiy
2021-03-11 1:34 ` Jason Gunthorpe
2021-03-11 1:42 ` Alexey Kardashevskiy
2021-03-11 2:00 ` Jason Gunthorpe
2021-03-11 7:54 ` Alexey Kardashevskiy
2021-03-11 9:44 ` Max Gurtovoy
2021-03-11 16:51 ` Jason Gunthorpe
2021-03-11 17:01 ` Jason Gunthorpe
2021-03-10 14:19 ` Alexey Kardashevskiy
2021-03-11 1:10 ` Max Gurtovoy
2021-03-19 15:23 ` Alex Williamson
2021-03-19 16:17 ` Jason Gunthorpe
2021-03-19 16:20 ` Christoph Hellwig
2021-03-19 16:28 ` Jason Gunthorpe
2021-03-19 16:34 ` Christoph Hellwig
2021-03-19 17:36 ` Alex Williamson
2021-03-19 20:07 ` Jason Gunthorpe
2021-03-19 21:08 ` Alex Williamson
2021-03-19 22:59 ` Jason Gunthorpe
2021-03-20 4:40 ` Alex Williamson
2021-03-21 12:58 ` Jason Gunthorpe
2021-03-22 16:40 ` Alex Williamson
2021-03-23 19:32 ` Jason Gunthorpe
2021-03-24 2:39 ` Alexey Kardashevskiy
2021-03-29 23:10 ` Alex Williamson
2021-04-01 13:04 ` Cornelia Huck [this message]
2021-04-01 13:12 ` Jason Gunthorpe
2021-04-01 21:49 ` Alex Williamson
2021-03-22 15:11 ` Christoph Hellwig
2021-03-22 16:44 ` Jason Gunthorpe
2021-03-23 13:17 ` Christoph Hellwig
2021-03-23 13:42 ` Jason Gunthorpe
2021-03-09 8:33 ` [PATCH 9/9] vfio/pci: export igd support into vendor vfio_pci driver Max Gurtovoy
2021-03-10 8:15 ` Christoph Hellwig
2021-03-10 12:31 ` Jason Gunthorpe
2021-03-11 11:37 ` Christoph Hellwig
2021-03-11 12:09 ` Max Gurtovoy
2021-03-11 15:43 ` Jason Gunthorpe
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