March 2016 - Devel - libvirt List Archives

[libvirt] [PATCH] Fix python error reporting for some storage operations
by Cole Robinson 07 Mar '25

07 Mar '25

In the python bindings, all vir* classes expect to be passed a virConnect object when instantiated. Before the storage stuff, these classes were only instantiated in virConnect methods, so the generator is hardcoded to pass 'self' as the connection instance to these classes. Problem is there are some methods that return pool or vol instances which aren't called from virConnect: you can lookup a storage volume's associated pool, and can lookup volumes from a pool. In these cases passing 'self' doesn't give the vir* instance a connection, so when it comes time to raise an exception crap hits the fan. Rather than rework the generator to accomodate this edge case, I just fixed the init functions for virStorage* to pull the associated connection out of the passed value if it's not a virConnect instance. Thanks, Cole diff --git a/python/generator.py b/python/generator.py index 01a17da..c706b19 100755 --- a/python/generator.py +++ b/python/generator.py @@ -962,8 +962,12 @@ def buildWrappers(): list = reference_keepers[classname] for ref in list: classes.write(" self.%s = None\n" % ref[1]) - if classname in [ "virDomain", "virNetwork", "virStoragePool", "virStorageVol" ]: + if classname in [ "virDomain", "virNetwork" ]: classes.write(" self._conn = conn\n") + elif classname in [ "virStorageVol", "virStoragePool" ]: + classes.write(" self._conn = conn\n" + \ + " if not isinstance(conn, virConnect):\n" + \ + " self._conn = conn._conn\n") classes.write(" if _obj != None:self._o = _obj;return\n") classes.write(" self._o = None\n\n"); destruct=None

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[libvirt] [PATCH] web docs -- macvtap mode explanation
by Stefan Berger 27 Oct '23

27 Oct '23

This adds more information about the different macvtap device modes. Regards, Stefan

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[libvirt] Supporting vhost-net and macvtap in libvirt for QEMU
by Anthony Liguori 27 Oct '23

27 Oct '23

Disclaimer: I am neither an SR-IOV nor a vhost-net expert, but I've CC'd people that are who can throw tomatoes at me for getting bits wrong :-) I wanted to start a discussion about supporting vhost-net in libvirt. vhost-net has not yet been merged into qemu but I expect it will be soon so it's a good time to start this discussion. There are two modes worth supporting for vhost-net in libvirt. The first mode is where vhost-net backs to a tun/tap device. This is behaves in very much the same way that -net tap behaves in qemu today. Basically, the difference is that the virtio backend is in the kernel instead of in qemu so there should be some performance improvement. Current, libvirt invokes qemu with -net tap,fd=X where X is an already open fd to a tun/tap device. I suspect that after we merge vhost-net, libvirt could support vhost-net in this mode by just doing -net vhost,fd=X. I think the only real question for libvirt is whether to provide a user visible switch to use vhost or to just always use vhost when it's available and it makes sense. Personally, I think the later makes sense. The more interesting invocation of vhost-net though is one where the vhost-net device backs directly to a physical network card. In this mode, vhost should get considerably better performance than the current implementation. I don't know the syntax yet, but I think it's reasonable to assume that it will look something like -net tap,dev=eth0. The effect will be that eth0 is dedicated to the guest. On most modern systems, there is a small number of network devices so this model is not all that useful except when dealing with SR-IOV adapters. In that case, each physical device can be exposed as many virtual devices (VFs). There are a few restrictions here though. The biggest is that currently, you can only change the number of VFs by reloading a kernel module so it's really a parameter that must be set at startup time. I think there are a few ways libvirt could support vhost-net in this second mode. The simplest would be to introduce a new tag similar to <source network='br0'>. In fact, if you probed the device type for the network parameter, you could probably do something like <source network='eth0'> and have it Just Work. Another model would be to have libvirt see an SR-IOV adapter as a network pool whereas it handled all of the VF management. Considering how inflexible SR-IOV is today, I'm not sure whether this is the best model. Has anyone put any more thought into this problem or how this should be modeled in libvirt? Michael, could you share your current thinking for -net syntax? -- Regards, Anthony Liguori

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Re: [libvirt] question about rdma migration
by Michael R. Hines 25 Oct '16

25 Oct '16

Hi Roy, On 02/09/2016 03:57 AM, Roy Shterman wrote: > Hi, > > I tried to understand the rdma-migration in qemu code and i have two > questions about it: > > 1. I'm working with qemu-kvm using libvirt and i'm getting > > MEMLOCK max locked-in-memory address space 65536 65536 bytes > > in qemu process so I don't understand how can you use rdma-pin-all > with such low MEMLOCK. > > I found a solution in libvirt to lock all vm memory in advance and to > enlarge MEMLOCK. > It uses memoryBacking locking and memory tuning hard_limit of vm > memory but I couldn't find a usage of this in rdma-migration code. > You're absolutey right, the RDMA migration code itself doesn't set this lock limit explicitly because there are system-wide restrictions in both appArmour, /etc/security, as well as SELINUX that restrict applications from arbitrarily setting their maximum memory lock limits. The other problem is CGROUPS: If someone sets a cgroup control for maximum memory and forgets about that mlock() limits, then there will be a conflict. So, libvirt must have a policy to deal with all of these possibilities, not just handle a special case for RDMA migration. The only way "simple" way (without patching the problems above) to apply a higher lock limit to QEMU is to set the ulimit for libvirt (or for QEMU if starting QEMU manually) in your environment or the command line with $ ulimit # before attempting the migration, then the RDMA subsystem will be able to lock the memory successfully. The other option is to use /etc/security/limits.conf and set the option for a specific libvirt process user and make sure your libvirt/qemu are not running as root. QEMU itself also has a "mlock" option built into the command line, but it also suffers from the same problem --- you have to find a way (currently) to increase the limit before using the option. > 2. Do you have any comparison of IOPS and bandwidth between TCP > migration and rdma migration? > Yes, lots of comparisons. http://wiki.qemu.org/Features/RDMALiveMigration http://www.canturkisci.com/ETC/papers/IBMJRD2011/preprint.pdf > Regards, > Roy > >

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[libvirt] Qemu: create empty cdrom
by Gromak Yuriy 19 Oct '16

19 Oct '16

Hello. Qemu is latest from master branch. Tryingto start a domain, which is connected toa blankcdrom: <disk type='file' device='cdrom'> <driver name='qemu' type='raw'/> <target dev='sdb' bus='scsi'/> <readonly/> <address type='drive' controller='0' target='1' bus='0' unit='0'/> </disk> But I get an error: qemu-system-x86_64: -drive if=none,id=drive-scsi0-0-1-0,readonly=on,format=raw: Can't use 'raw' as a block driver for the protocol level.

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[libvirt] [libvirt-glib/libvirt-gconfig 00/17] Graphics: Introduce the new Remote and Local classes (and also implement a few missing methods).
by Fabiano Fidêncio 06 Sep '16

06 Sep '16

While trying to use libvirt-gobject and libvirt-gconfig for accessing VMs and looking at their config, instead of using libvirt and parsing XML directly, I found out that a few methods have been missing and that libvirt-gconfig is not exactly thought for the "reading their config" use case (see more explanations on the 10th and 14th commits. This series, unfortunately, introduces an ABI breakage. Fabiano Fidêncio (17): gconfig: Implement gvir_config_domain_graphics_vnc_get_autoport() gconfig: Implement gvir_config_domain_graphics_spice_get_autoport() gconfig: Implement gvir_config_domain_graphics_rdp_get_autoport() gconfig: Implement gvir_config_domain_graphics_sdl_get_display() gconfig: Implement gvir_config_domain_graphics_sdl_get_fullscreen() gconfig: Implement gvir_config_domain_graphics_spice_get_tls_port() gconfig: Implement gvir_config_domain_graphics_spice_{get,set}_host() gconfig: Implement gvir_config_domain_graphics_vnc_{get,set}_host() gconfig: Implement gvir_config_domain_graphics_rdp_{get,set}_host() gconfig: Add GVirCofigDomainGraphicsRemote class gconfig: Adapt GVirConfigDomainGraphicsSpice to GVirConfigDomainGraphicsRemote gconfig: Adapt GVirConfigDomainGraphicsRdp to GVirConfigDomainGraphicsRemote gconfig: Adapt GVirConfigDomainGraphicsVnc to GVirConfigDomainGraphicsRemote gconfig: Add GVirCofigDomainGraphicsLocal class gconfig: Adapt GVirConfigDomainGraphicsSdl to GVirConfigDomainGraphicsLocal gconfig: Adapt GVirConfigDomainGraphicsDesktop to GVirConfigDomainGraphicsLocal gconfig,graphics: Avoid crash when gvir_config_object_new_from_xml() returns NULL libvirt-gconfig/Makefile.am | 4 + .../libvirt-gconfig-domain-graphics-desktop.c | 14 ++- .../libvirt-gconfig-domain-graphics-desktop.h | 4 +- .../libvirt-gconfig-domain-graphics-local.c | 97 +++++++++++++++++++ .../libvirt-gconfig-domain-graphics-local.h | 68 ++++++++++++++ .../libvirt-gconfig-domain-graphics-rdp.c | 32 ++++++- .../libvirt-gconfig-domain-graphics-rdp.h | 9 +- .../libvirt-gconfig-domain-graphics-remote.c | 103 +++++++++++++++++++++ .../libvirt-gconfig-domain-graphics-remote.h | 70 ++++++++++++++ .../libvirt-gconfig-domain-graphics-sdl.c | 19 +++- .../libvirt-gconfig-domain-graphics-sdl.h | 6 +- .../libvirt-gconfig-domain-graphics-spice.c | 40 +++++++- .../libvirt-gconfig-domain-graphics-spice.h | 10 +- .../libvirt-gconfig-domain-graphics-vnc.c | 32 ++++++- .../libvirt-gconfig-domain-graphics-vnc.h | 9 +- libvirt-gconfig/libvirt-gconfig.h | 2 + libvirt-gconfig/libvirt-gconfig.sym | 20 ++++ po/POTFILES.in | 2 + 18 files changed, 513 insertions(+), 28 deletions(-) create mode 100644 libvirt-gconfig/libvirt-gconfig-domain-graphics-local.c create mode 100644 libvirt-gconfig/libvirt-gconfig-domain-graphics-local.h create mode 100644 libvirt-gconfig/libvirt-gconfig-domain-graphics-remote.c create mode 100644 libvirt-gconfig/libvirt-gconfig-domain-graphics-remote.h -- 2.5.0

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[libvirt] [RFC PATCH 0/2] nodeinfo: PPC64: Fix topology and siblings info on capabilities and nodeinfo
by Shivaprasad G Bhat 21 Jul '16

21 Jul '16

The nodeinfo output was fixed earlier to reflect the actual cpus available in KVM mode on PPC64. The earlier fixes covered the aspect of not making a host look overcommitted when its not. The current fixes are aimed at helping the users make better decisions on the kind of guest cpu topology that can be supported on the given sucore_per_core setting of KVM host and also hint the way to pin the guest vcpus efficiently. I am planning to add some test cases once the approach is accepted. With respect to Patch 2: The second patch adds a new element to the cpus tag and I need your inputs on if that is okay. Also if there is a better way. I am not sure if the existing clients have RNG checks that might fail with the approach. Or if the checks are not enoforced on the elements but only on the tags. With my approach if the rng checks pass, the new element "capacity" even if ignored by many clients would have no impact except for PPC64. To the extent I looked at code, the siblings changes dont affect existing libvirt functionality. Please do let me know otherwise. --- Shivaprasad G Bhat (2): nodeinfo: Reflect guest usable host topology on PPC64 Introduce capacity to virCapsHostNUMACellCPU to help vcpu pinning decisions src/conf/capabilities.c | 3 + src/conf/capabilities.h | 1 src/nodeinfo.c | 51 ++++++++++++++++++++++-- tests/vircaps2xmldata/vircaps-basic-4-4-2G.xml | 32 ++++++++------- tests/vircaps2xmltest.c | 1 5 files changed, 67 insertions(+), 21 deletions(-) -- Signature

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[libvirt] Bump tar format?
by Andrea Bolognani 15 Jun '16

15 Jun '16

Hi everyone, commit cc3d52e[1] has apparently broken 'make dist' for at least some platforms: Fedora 20 is fine[2], but both Fedora 21 and rawhide[3][4] are currently failing. My laptop is running Fedora 22 and can make dist just fine, which is of course very confusing. The issue is caused by the following tar error: tar: libvirt-1.2.18/tests/nodeinfodata/linux-deconfigured-cpus/ \ node/node0/cpu16/topology/core_siblings_list: \ link name is too long; not dumped There seem to be basically two ways to solve the failure: 1. rename the test case, making it shorter; 2. bump tar format from ustar, which has limitations on the length of file names, to posix/pax, which has no such limitations. I'm not a fan of the former option because short names are usually very opaque, see tests/nodeinfodata/linux-test[0-8] for some perfect examples. On the other hand, I'm not sure whether bumping the tar version would affect portability in a significant way: the automake documentation[5] reports that this format is very young and should probably be restricted to packages that target only very modern platforms but the GNU tar documentation[6], while containing some warnings as well, suggest that this format is going to become the default. Any suggestions on how to proceed? Cheers. [1] https://www.redhat.com/archives/libvir-list/2015-July/msg00662.html [2] https://ci.centos.org/view/libvirt-project/job/libvirt-daemon -rpm/systems=libvirt-fedora-20/327/ [3] https://ci.centos.org/view/libvirt-project/job/libvirt-daemon -rpm/systems=libvirt-fedora-21/327/ [4] https://ci.centos.org/view/libvirt-project/job/libvirt-daemon -rpm/systems=libvirt-fedora-rawhide/327/ [5] https://www.gnu.org/software/automake/manual/html_node/List-of -Automake-options.html [6] http://www.gnu.org/software/tar/manual/html_chapter/tar_8.html -- Andrea Bolognani Software Engineer - Virtualization Team

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[libvirt] Libvirt multi queue support
by Naor Shlomo 14 Jun '16

14 Jun '16

Hello experts, Could anyone please tell me if Multi Queue it fully supported in Libvirt and if so what version contains it? Thanks, Naor

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[libvirt] [PATCH] xen: Also add sub-type for driver=tap2 in xen-xm
by Philipp Hahn 07 Jun '16

07 Jun '16

tap2 only handles 'aio', but not 'raw', which must be explicitly given: | $ virsh domxml-to-native yyy.xml > yyy.xm | $ xm new yyy.xm | Error: tap:/srv/xen/xxx.img not a valid disk type | $ sed -i -e 's/tap2:/&aio:/' yyy.xm | $ xm new yyy.xm Fix reading and writing "xen-xm" format for "tap2" by handling it the same as "tap". --- src/xenconfig/xen_xm.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/src/xenconfig/xen_xm.c b/src/xenconfig/xen_xm.c index e09d97e..6556886 100644 --- a/src/xenconfig/xen_xm.c +++ b/src/xenconfig/xen_xm.c @@ -196,7 +196,8 @@ xenParseXMDisk(virConfPtr conf, virDomainDefPtr def) } /* And the sub-type for tap:XXX: type */ - if (STREQ_NULLABLE(virDomainDiskGetDriver(disk), "tap")) { + if (STREQ_NULLABLE(virDomainDiskGetDriver(disk), "tap") || + STREQ_NULLABLE(virDomainDiskGetDriver(disk), "tap2")) { char *driverType; if (!(tmp = strchr(src, ':'))) @@ -298,7 +299,7 @@ xenFormatXMDisk(virConfValuePtr list, else type = virStorageFileFormatTypeToString(format); virBufferAsprintf(&buf, "%s:", driver); - if (STREQ(driver, "tap")) + if (STREQ(driver, "tap") || STREQ(driver, "tap2")) virBufferAsprintf(&buf, "%s:", type); } else { switch (virDomainDiskGetType(disk)) { -- 2.1.4

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