Libvirt provides a portable, long term stable C API for managing the virtualization technologies provided by many operating systems. It includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER Hypervisor.
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Erik Skultety 49cb59778a hostdev: mdev: Lookup mdevs by sysfs path rather than mdev struct
The lookup didn't do anything apart from comparing the sysfs paths
anyway since that's what makes each mdev unique.
The most ridiculous usage of the old logic was in
virHostdevReAttachMediatedDevices where in order to drop an mdev
hostdev from the list of active devices we first had to create a new
mdev and use it in the lookup call. Why couldn't we have used the
hostdev directly? Because the hostdev and mdev structures are
incompatible.

The way mdevs are currently removed is via a write to a specific sysfs
attribute. If you do it while the machine which has the mdev assigned
is running, the write call may block (with a new enough kernel, with
older kernels it would return a write error!) until the device
is no longer in use which is when the QEMU process exits.

The interesting part here comes afterwards when we're cleaning up and
call virHostdevReAttachMediatedDevices. The domain doesn't exist
anymore, so the list of active hostdevs needs to be updated and the
respective hostdevs removed from the list, but remember we had to
create an mdev object in the memory in order to find it in the list
first which will fail because the write to sysfs had already removed
the mdev instance from the host system.
And so the next time you try to start the same domain you'll get:

"Requested operation is not valid: mediated device <path> is in use by
driver QEMU, domain <name>"

Fixes: https://gitlab.com/libvirt/libvirt/-/issues/119

Signed-off-by: Erik Skultety <eskultet@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
2021-01-08 08:10:02 +01:00
.ctags.d maint: Add support for .ctags.d 2019-05-31 17:54:28 +02:00
.github github: skip lockdown of old issues/prs 2020-04-07 17:50:54 +01:00
.gitlab/issue_templates gitlab: Add issue template for a feature request 2020-12-02 09:11:27 +01:00
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ci ci: containers: Refresh the Dockerfiles 2020-12-15 09:52:14 +00:00
docs schemas: Allow direct children of <filesystem/> to be interleaved 2021-01-06 13:44:19 +01:00
examples libvirt: support memory failure event 2020-10-23 09:41:52 +02:00
include virsh: nodedev: filter by AP Matrix capability 2020-12-09 14:03:05 +01:00
po Update translation files 2021-01-04 14:53:56 +01:00
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src hostdev: mdev: Lookup mdevs by sysfs path rather than mdev struct 2021-01-08 08:10:02 +01:00
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CONTRIBUTING.rst meson: adjust our documentation to mention meson instead of autoconf 2020-08-03 09:27:09 +02:00
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gitdm.config gitdm: add 'ibm' file 2019-10-18 17:32:52 +02:00
libvirt-admin.pc.in Add libvirt-admin library 2015-06-16 13:46:20 +02:00
libvirt-lxc.pc.in Add pkg-config files for libvirt-qemu & libvirt-lxc 2014-06-23 16:17:27 +01:00
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Libvirt API for virtualization

Libvirt provides a portable, long term stable C API for managing the virtualization technologies provided by many operating systems. It includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER Hypervisor.

For some of these hypervisors, it provides a stateful management daemon which runs on the virtualization host allowing access to the API both by non-privileged local users and remote users.

Layered packages provide bindings of the libvirt C API into other languages including Python, Perl, PHP, Go, Java, OCaml, as well as mappings into object systems such as GObject, CIM and SNMP.

Further information about the libvirt project can be found on the website:

https://libvirt.org

License

The libvirt C API is distributed under the terms of GNU Lesser General Public License, version 2.1 (or later). Some parts of the code that are not part of the C library may have the more restrictive GNU General Public License, version 2.0 (or later). See the files COPYING.LESSER and COPYING for full license terms & conditions.

Installation

Instructions on building and installing libvirt can be found on the website:

https://libvirt.org/compiling.html

Contributing

The libvirt project welcomes contributions in many ways. For most components the best way to contribute is to send patches to the primary development mailing list. Further guidance on this can be found on the website:

https://libvirt.org/contribute.html

Contact

The libvirt project has two primary mailing lists:

Further details on contacting the project are available on the website:

https://libvirt.org/contact.html