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From: Alex Williamson <alex.williamson@redhat.com>
To: Cornelia Huck <cohuck@redhat.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: Fri, 24 May 2019 08:43:22 -0600
Message-ID: <20190524084322.3e52f1ca@x1.home> (raw)
In-Reply-To: <20190524121106.16e08562.cohuck@redhat.com>

On Fri, 24 May 2019 12:11:06 +0200
Cornelia Huck <cohuck@redhat.com> wrote:

> On Thu, 23 May 2019 17:20:01 -0600
> Alex Williamson <alex.williamson@redhat.com> wrote:
> 
> > Hi,
> > 
> > Currently mediated device management, much like SR-IOV VF management,
> > is largely left as an exercise for the user.  This is an attempt to
> > provide something and see where it goes.  I doubt we'll solve
> > everyone's needs on the first pass, but maybe we'll solve enough and
> > provide helpers for the rest.  Without further ado, I'll point to what
> > I have so far:
> > 
> > https://github.com/awilliam/mdevctl
> > 
> > This is inspired by driverctl, which is also a bash utility.  mdevctl
> > uses udev and systemd to record and recreate mdev devices for
> > persistence and provides a command line utility for querying, listing,
> > starting, stopping, adding, and removing mdev devices.  Currently, for
> > better or worse, it considers anything created to be persistent.  I can
> > imagine a global configuration option that might disable this and
> > perhaps an autostart flag per mdev device, such that mdevctl might
> > simply "know" about some mdevs but not attempt to create them
> > automatically.  Clearly command line usage help, man pages, and
> > packaging are lacking as well, release early, release often, plus this
> > is a discussion starter to see if perhaps this is sufficient to meet
> > some needs.
> > 
> > Originally I thought about making a utility to manage both mdev and
> > SR-IOV VFs all in one, but it seemed more natural to start here
> > (besides, I couldn't think of a good name for the combined utility).
> > If this seems useful, maybe I'll start on a vfctl for SR-IOV and we'll
> > see whether they have enough synergy to become one.
> > 
> > It would be really useful if s390 folks could help me understand
> > whether it's possible to glean all the information necessary to
> > recreate a ccw or ap mdev device from sysfs.  I expect the file where
> > we currently only store the mdev_type to evolve into something that
> > includes more information to facilitate more complicated devices.  For
> > now I make no claims to maintaining compatibility of recorded mdev
> > devices, it will absolutely change, but I didn't want to get bogged
> > down in making sure I don't accidentally source a root kit hidden in an
> > mdev config file.  
> 
> I played a bit with it on my LPAR, and it is at least not obviously
> broken with vfio-ccw :) I don't have any ap devices to play with,
> though.

Awesome, that's a good start.  Thanks for testing!


> > I'm also curious how or if libvirt or openstack might use this.  If
> > nothing else, it makes libvirt hook scripts easier to write, especially
> > if we add an option not to autostart mdevs, or if users don't mind
> > persistent mdevs, maybe there's nothing more to do.
> > 
> > BTW, feel free to clean up by bash, I'm a brute force and ignorance
> > shell coder ;)    
> 
> Not that I'm a good shell coder, but I sent you a pull req at least
> adding a basic help text ;)
> 
> I have not yet looked at most of the code, though.

Pulled, thanks again!  I'll continue to try to fill in some of the
gaps.  I also forgot to mention that the integration with systemd means
that mdevs that mdevctl knows about can be started and stopped with
systemctl, ie:

# systemctl {start|stop} mdev@$UUID.service

You'll see that sbin/mdevctl start/stop-mdev is effectively just an
alias to this.  Thanks,

Alex

  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 [this message]
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
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

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