KVM Archive on lore.kernel.org
 help / color / Atom feed
From: Cornelia Huck <cohuck@redhat.com>
To: Eric Farman <farman@linux.ibm.com>, Halil Pasic <pasic@linux.ibm.com>
Cc: linux-s390@vger.kernel.org, kvm@vger.kernel.org,
	Cornelia Huck <cohuck@redhat.com>
Subject: [PATCH RFC 0/1] s390dbf logging for vfio-ccw
Date: Fri, 16 Aug 2019 17:15:04 +0200
Message-ID: <20190816151505.9853-1-cohuck@redhat.com> (raw)

The current discussions around uuids and mdev devices got me thinking,
and I realized that the uuid is an interesting information for
debugging devices.

Currently, vfio-ccw does not really log any debug data (there's just
a lone trace event). The common I/O layer has logged interesting
information into the s390dbf for a long time; this has been very
useful in the past, as the logged information can be accessed in a
crash dump (e.g. by the crash tool). We cannot log directly into
the common I/O layer debug features, though, as vfio-ccw may be a
module.

Another limitation is that for the sprintf-type debug feature, any
string logged via '%s' must outlive the debug feature (as it is not
copied for performance reasons). That means that logging the device
name is right out, as devices may go away (the current common I/O
layer code logs the numerical values of ssid/subchannel number instead);
logging the uuid of an mdev device via %pU just works fine, though.

My patch just logs some basics right now, we can certainly add more
events. We should also think about adding more trace events: they
may serve a similar purpose, especially if we should enhance the vfio
code with trace events in the future (so that we can correlate those
trace events with the vfio-ccw trace events, just as we can correlate
the s390dbf events with the common I/O layer dbf events to get a more
complete picture.)

Cornelia Huck (1):
  vfio-ccw: add some logging

 drivers/s390/cio/vfio_ccw_drv.c     | 50 ++++++++++++++++++++++++++--
 drivers/s390/cio/vfio_ccw_fsm.c     | 51 ++++++++++++++++++++++++++++-
 drivers/s390/cio/vfio_ccw_ops.c     | 10 ++++++
 drivers/s390/cio/vfio_ccw_private.h | 17 ++++++++++
 4 files changed, 124 insertions(+), 4 deletions(-)

-- 
2.20.1


             reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-16 15:15 Cornelia Huck [this message]
2019-08-16 15:15 ` [PATCH RFC 1/1] vfio-ccw: add some logging Cornelia Huck
2019-08-21 15:54   ` Eric Farman
2019-08-23 10:44     ` Cornelia Huck
2019-08-23 11:48   ` 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=20190816151505.9853-1-cohuck@redhat.com \
    --to=cohuck@redhat.com \
    --cc=farman@linux.ibm.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-s390@vger.kernel.org \
    --cc=pasic@linux.ibm.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