Introduces hot plug/unplug support for the vfio-ap device.
To hot plug a vfio-ap device using the QEMU device_add command:
(qemu) device_add vfio-ap,sysfsdev=$path-to-mdev
Where $path-to-mdev is the absolute path to the mediated matrix device
to which AP resources to be used by the guest have been assigned.
A vfio-ap device can be hot plugged only if:
1. A vfio-ap device has not been attached to the virtual machine's ap-bus
via the QEMU command line or a prior hot plug action.
2. The guest was started with the CPU model feature for AP enabled
(e.g., -cpu host,ap=on)
To hot unplug a vfio-ap device using the QEMU device_del command:
(qemu) device_del vfio-ap,sysfsdev=$path-to-mdev
Where $path-to-mdev is the absolute path to the mediated matrix device
specified when the vfio-ap device was attached to the virtual machine's
ap-bus.
A vfio-ap device can be hot unplugged only if:
1. A vfio-ap device has been attached to the virtual machine's ap-bus
via the QEMU command line or a prior hot plug action.
2. The guest was started with the CPU model feature for AP enabled
(e.g., -cpu host,ap=on)
Please note that a hot plug handler is not necessary for the vfio-ap device
because the AP matrix configuration for the guest is performed by the
kernel device driver when the vfio-ap device is realized. The vfio-ap device
represents a VFIO mediated device created in the host sysfs for use by a guest.
The mdev device is configured with an AP matrix (i.e., adapters and domains) via
its sysfs attribute interfaces prior to starting the guest or plugging a vfio-ap
device in. When the device is realized, a file descriptor is opened on the mdev
device which results in a callback to the vfio_ap kernel device driver. The
device driver then configures the AP matrix in the guest's SIE state description
from the AP matrix assigned via the mdev device's sysfs interfaces. The AP
devices will be created for the guest when the AP bus running on the guest
subsequently performs its periodic scan for AP devices.
The qdev_simple_device_unplug_cb() callback function is used for the same
reaons; namely, the vfio_ap kernel device driver will perform the AP resource
de-configuration for the guest when the vfio-ap device is unplugged. When the
vfio-ap device is unrealized, the mdev device file descriptor is closed which
results in a callback to the vfio_ap kernel device driver. The device driver
then clears the AP matrix configuration in the guest's SIE state description
and resets all of the affected queues. The AP devices created for the guest
will be removed when the AP bus running on the guest subsequently performs
its periodic scan and finds there are no longer any AP resources assigned to the
guest.
Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Tested-by: Pierre Morel <pmorel@linux.ibm.com>
Message-Id: <1550519397-25359-2-git-send-email-akrowiak@linux.ibm.com>
[CH: adapt to changed qbus_set_hotplug_handler() signature]
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
QEMU README
===========
QEMU is a generic and open source machine & userspace emulator and
virtualizer.
QEMU is capable of emulating a complete machine in software without any
need for hardware virtualization support. By using dynamic translation,
it achieves very good performance. QEMU can also integrate with the Xen
and KVM hypervisors to provide emulated hardware while allowing the
hypervisor to manage the CPU. With hypervisor support, QEMU can achieve
near native performance for CPUs. When QEMU emulates CPUs directly it is
capable of running operating systems made for one machine (e.g. an ARMv7
board) on a different machine (e.g. an x86_64 PC board).
QEMU is also capable of providing userspace API virtualization for Linux
and BSD kernel interfaces. This allows binaries compiled against one
architecture ABI (e.g. the Linux PPC64 ABI) to be run on a host using a
different architecture ABI (e.g. the Linux x86_64 ABI). This does not
involve any hardware emulation, simply CPU and syscall emulation.
QEMU aims to fit into a variety of use cases. It can be invoked directly
by users wishing to have full control over its behaviour and settings.
It also aims to facilitate integration into higher level management
layers, by providing a stable command line interface and monitor API.
It is commonly invoked indirectly via the libvirt library when using
open source applications such as oVirt, OpenStack and virt-manager.
QEMU as a whole is released under the GNU General Public License,
version 2. For full licensing details, consult the LICENSE file.
Building
========
QEMU is multi-platform software intended to be buildable on all modern
Linux platforms, OS-X, Win32 (via the Mingw64 toolchain) and a variety
of other UNIX targets. The simple steps to build QEMU are:
mkdir build
cd build
../configure
make
Additional information can also be found online via the QEMU website:
https://qemu.org/Hosts/Linux
https://qemu.org/Hosts/Mac
https://qemu.org/Hosts/W32
Submitting patches
==================
The QEMU source code is maintained under the GIT version control system.
git clone https://git.qemu.org/git/qemu.git
When submitting patches, one common approach is to use 'git
format-patch' and/or 'git send-email' to format & send the mail to the
qemu-devel@nongnu.org mailing list. All patches submitted must contain
a 'Signed-off-by' line from the author. Patches should follow the
guidelines set out in the HACKING and CODING_STYLE files.
Additional information on submitting patches can be found online via
the QEMU website
https://qemu.org/Contribute/SubmitAPatch
https://qemu.org/Contribute/TrivialPatches
The QEMU website is also maintained under source control.
git clone https://git.qemu.org/git/qemu-web.git
https://www.qemu.org/2017/02/04/the-new-qemu-website-is-up/
A 'git-publish' utility was created to make above process less
cumbersome, and is highly recommended for making regular contributions,
or even just for sending consecutive patch series revisions. It also
requires a working 'git send-email' setup, and by default doesn't
automate everything, so you may want to go through the above steps
manually for once.
For installation instructions, please go to
https://github.com/stefanha/git-publish
The workflow with 'git-publish' is:
$ git checkout master -b my-feature
$ # work on new commits, add your 'Signed-off-by' lines to each
$ git publish
Your patch series will be sent and tagged as my-feature-v1 if you need to refer
back to it in the future.
Sending v2:
$ git checkout my-feature # same topic branch
$ # making changes to the commits (using 'git rebase', for example)
$ git publish
Your patch series will be sent with 'v2' tag in the subject and the git tip
will be tagged as my-feature-v2.
Bug reporting
=============
The QEMU project uses Launchpad as its primary upstream bug tracker. Bugs
found when running code built from QEMU git or upstream released sources
should be reported via:
https://bugs.launchpad.net/qemu/
If using QEMU via an operating system vendor pre-built binary package, it
is preferable to report bugs to the vendor's own bug tracker first. If
the bug is also known to affect latest upstream code, it can also be
reported via launchpad.
For additional information on bug reporting consult:
https://qemu.org/Contribute/ReportABug
Contact
=======
The QEMU community can be contacted in a number of ways, with the two
main methods being email and IRC
- qemu-devel@nongnu.org
https://lists.nongnu.org/mailman/listinfo/qemu-devel
- #qemu on irc.oftc.net
Information on additional methods of contacting the community can be
found online via the QEMU website:
https://qemu.org/Contribute/StartHere
-- End