KVM Archive on lore.kernel.org
 help / color / Atom feed
From: Cornelia Huck <cohuck@redhat.com>
To: Alex Williamson <alex.williamson@redhat.com>,
	Halil Pasic <pasic@linux.ibm.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"Libvirt Devel" <libvir-list@redhat.com>,
	"Kirti Wankhede" <kwankhede@nvidia.com>,
	"Erik Skultety" <eskultet@redhat.com>,
	"Pavel Hrdina" <phrdina@redhat.com>,
	"Daniel P. Berrangé" <berrange@redhat.com>,
	"Sylvain Bauza" <sbauza@redhat.com>
Subject: Re: mdevctl: A shoestring mediated device management and persistence utility
Date: Wed, 12 Jun 2019 09:14:39 +0200
Message-ID: <20190612091439.3a33f17b.cohuck@redhat.com> (raw)
In-Reply-To: <20190611142822.238ef424@x1.home>

On Tue, 11 Jun 2019 14:28:22 -0600
Alex Williamson <alex.williamson@redhat.com> wrote:

> On Tue, 11 Jun 2019 21:45:08 +0200
> Cornelia Huck <cohuck@redhat.com> wrote:
> 
> > On Fri, 7 Jun 2019 18:06:30 +0200
> > Halil Pasic <pasic@linux.ibm.com> wrote:

> > > I guess for vfio-ccw one needs to make sure that the ccw device is bound
> > > to the vfio-ccw driver first, and only after that can one use  
> > > create-mdev to create the mdev on top of the subchannel.
> > > 
> > > So to make this work persistently (survive a reboot) one would need to
> > > take care of the subchannel getting bound to the right vfio_ccw driver
> > > before mdevctl is called. Right?
> > > 
> > > BTW how does this concurrence situation between the drivers io_subchannel
> > > and vfio_ccw work? Especially if both are build in?    
> > 
> > If you have two drivers that match to the same device type, you'll
> > always have the issue that the driver that is first matched with the
> > device will bind to it and you have to do the unbind/rebind dance to
> > get it bound to the correct device driver. (I guess that this was the
> > basic motivation behind the ap bus default driver infrastructure,
> > right?) I think that in our case the io_subchannel driver will be
> > called first (alphabetical order and the fact that vfio-ccw will often
> > be a module). I'm not sure if it is within the scope of mdevctl to
> > ensure that the device is bound to the correct driver, or if it rather
> > should work with devices already bound to the correct driver only.
> > Maybe a separate udev-rules generator?  
> 
> Getting a device bound to a specific driver is exactly the domain of
> driverctl.  Implement the sysfs interfaces driverctl uses and see if it
> works.  Driverctl defaults to PCI and knows some extra things about
> PCI, but appears to be written to be generally bus agnostic.  Thanks,
> 
> Alex

Ok, looked at driverctl. Extending this one for non-PCI seems like a
reasonable path. However, we would also need to extend any non-PCI
device type we want to support with a driver_override attribute like
you did for PCI in 782a985d7af26db39e86070d28f987cad2 -- so this is
only for newer kernels. Adding that attribute for subchannels looks
feasible at a glance, but I have not tried to actually do it :)

Halil, do you think that would make sense?

[This might also help with the lcs vs. ctc confusion on a certain 3088
cu model if this is added for ccw devices as well; but I'm not sure if
these are still out in the wild at all. Probably not worth the effort
for that.]

  reply index

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-23 23:20 Alex Williamson
2019-05-24 10:11 ` Cornelia Huck
2019-05-24 14:43   ` Alex Williamson
2019-06-07 16:06   ` Halil Pasic
2019-06-11 19:45     ` Cornelia Huck
2019-06-11 20:28       ` Alex Williamson
2019-06-12  7:14         ` Cornelia Huck [this message]
2019-06-12 15:54           ` Halil Pasic
2019-06-13 10:02             ` Cornelia Huck
2019-06-12 15:07       ` Halil Pasic
2019-06-13 16:17 ` Christophe de Dinechin
2019-06-13 16:35   ` Alex Williamson
2019-06-14  9:54     ` [libvirt] " Christophe de Dinechin
2019-06-14 14:23       ` Alex Williamson
2019-06-14 15:06         ` Christophe de Dinechin
2019-06-14 16:04           ` Alex Williamson
2019-06-17 16:03             ` Cornelia Huck
2019-06-17 14:00 ` Daniel P. Berrangé
2019-06-17 14:54   ` Alex Williamson
2019-06-17 15:10     ` Daniel P. Berrangé
2019-06-17 17:05       ` Alex Williamson
2019-06-18  8:44         ` Daniel P. Berrangé
2019-06-18 11:01         ` Cornelia Huck
     [not found]           ` <CALOCmukPWiXiM+mN0hCTvSwfdHy5UdERU8WnvOXiBrMQ9tH3VA@mail.gmail.com>
2019-06-18 22:12             ` Alex Williamson
2019-06-19  7:28               ` Daniel P. Berrangé
2019-06-19  9:46                 ` Cornelia Huck
2019-06-19 18:46                   ` Alex Williamson
2019-06-20  8:24                     ` Daniel P. Berrangé
     [not found]               ` <CALOCmu=6Xmw-_-SVXujCEcgPY2CQiBQKgfUMJ45WnZ_9XORyUw@mail.gmail.com>
2019-06-19  9:57                 ` Cornelia Huck
2019-06-19 19:53                 ` Alex Williamson
2019-06-25 22:52 ` Alex Williamson
2019-06-26  9:58   ` Cornelia Huck
2019-06-26 14:37     ` Alex Williamson
2019-06-27  1:53       ` Alex Williamson
2019-06-27 12:26         ` Cornelia Huck
2019-06-27 15:00           ` Matthew Rosato
2019-06-27 15:38             ` Alex Williamson
2019-06-27 16:13               ` Matthew Rosato
2019-06-27 21:15               ` Alex Williamson
2019-06-28  1:57                 ` Alex Williamson
2019-06-28  9:06                   ` Cornelia Huck
2019-06-28 14:01                     ` Matthew Rosato
2019-06-28 17:05                     ` Alex Williamson
2019-07-01  8:20                       ` Cornelia Huck
2019-07-01 14:40                         ` Alex Williamson
2019-07-01 17:13                           ` Cornelia Huck

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190612091439.3a33f17b.cohuck@redhat.com \
    --to=cohuck@redhat.com \
    --cc=alex.williamson@redhat.com \
    --cc=berrange@redhat.com \
    --cc=eskultet@redhat.com \
    --cc=kvm@vger.kernel.org \
    --cc=kwankhede@nvidia.com \
    --cc=libvir-list@redhat.com \
    --cc=pasic@linux.ibm.com \
    --cc=phrdina@redhat.com \
    --cc=sbauza@redhat.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

KVM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/kvm/0 kvm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kvm kvm/ https://lore.kernel.org/kvm \
		kvm@vger.kernel.org kvm@archiver.kernel.org
	public-inbox-index kvm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.kvm


AGPL code for this site: git clone https://public-inbox.org/ public-inbox