July 2010 - 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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[libvirt] [PATCH 0/4] Multiple problems with saving to block devices
by Daniel P. Berrange 24 Mar '13

24 Mar '13

This patch series makes it possible to save to a block device, instead of a plain file. There were multiple problems - WHen save failed, we might de-reference a NULL pointer - When save failed, we unlinked the device node !! - The approach of using >> to append, doesn't work with block devices - CGroups was blocking QEMU access to the block device when enabled One remaining problem is not in libvirt, but rather QEMU. The QEMU exec: based migration often fails to detect failure of the command and will thus hang forever attempting a migration that'll never succeed! Fortunately you can now work around this in libvirt using the virsh domjobabort command

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[libvirt] libvirt(-java): virDomainMigrateSetMaxDowntime
by Thomas Treutner 15 Sep '11

15 Sep '11

Hi, I'm facing some troubles with virDomainMigrate & virDomainMigrateSetMaxDowntime. The core problem is that KVM's default value for the maximum allowed downtime is 30ms (max_downtime in migration.c, it's nanoseconds there; 0.12.3) which is too low for my VMs when they're busy (~50% CPU util and above). Migrations then take literally forever, I had to abort them after 15 minutes or so. I'm using GBit Ethernet, so plenty bandwidth should be available. Increasing the allowed downtime to 50ms seems to help, but I have not tested situations where the VM is completely utilized. Anyways, the default value is too low for me, so I tried virDomainMigrateSetMaxDowntime resp. the Java wrapper function. Here I'm facing a problem I can overcome only with a quite crude hack: org.libvirt.Domain.migrate(..) blocks until the migration is done, which is of course reasonable. So I tried calling migrateSetMaxDowntime(..) before migrating, causing an error: "Requested operation is not valid: domain is not being migrated" This tells me that calling migrateSetMaxDowntime is only allowed during migrations. As I'm migrating VMs automatically and without any user intervention I'd need to create some glue code that runs in an extra thread, waiting "some time" hoping that the migration was kicked off in the main thread yet and then calling migrateSetMaxDowntime. I'd like to avoid such quirks in the long run, if possible. So my question: Would it be possible to extend the migrate() method resp. virDomainMigrate() function with an optional maxDowntime parameter that is passed down as QEMU_JOB_SIGNAL_MIGRATE_DOWNTIME so that qemuDomainWaitForMigrationComplete would set the value? Or are there easier ways? Thanks and regards, -t

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[libvirt] (how much) support for kqemu domain
by John Lumby 06 Jun '11

06 Jun '11

I am wondering about the extent to which "old" qemu-0.11.1 and kqemu-1.4.0 are supported by virt-manager. I see I can specify --virt-type=kqemu on virt-install and it remembers domain type='kqemu', and does things such as refusing to start the vm if the kqemu kernel mod not loaded, but it seems it does not tack on the -enable-kqemu -kernel-kqemu options on to the qemu command line. There is really not much point in trying to start a qemu-based vm with neither hardware kvm nor kqemu ... I can work around it with an override script to intercept the qemu command, but does anyone think virt-manager ought to do this for me? John Lumby _________________________________________________________________

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[libvirt] xen:/// vs. xen://FQDN/ vs xen+unix:/// discrepancy
by Philipp Hahn 18 Mar '11

18 Mar '11

Hello, I regularly observe the problem, that depending on the libvirt-URL I get different information: root@xen4# virsh -c xen://xen4.domain.name/ list Id Name State ---------------------------------- root@xen4# virsh -c xen:/// list Id Name State ---------------------------------- 0 Domain-0 running 1 dos4 idle root@xen4# virsh -c xen+unix:/// list Id Name State ---------------------------------- root@xen4# xm li Name ID Mem VCPUs State Time(s) Domain-0 0 2044 2 r----- 419.7 dos4 1 4 1 -b---- 33.4 Has somebody observed the same problem and/or can give me any advise on where to look for the problem? I'm running a Debian-Lenny based OS with libvirt-0.8.2 on Xen-3.4.3 with a 2.6.32 kernel. Sincerely Philipp Hahn -- Philipp Hahn Open Source Software Engineer hahn(a)univention.de Univention GmbH Linux for Your Business fon: +49 421 22 232- 0 Mary-Somerville-Str.1 28359 Bremen fax: +49 421 22 232-99 http://www.univention.de

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[libvirt] website: API reference for virterror contains libvirt API also
by Matthias Bolte 17 Jan '11

17 Jan '11

The API reference website [1] for virterror contains the API reference for virterror as expected. But the complete libvirt API reference, that is already found at [2], is appended too. I looked into the XSLT process that generates those two HTML files from the libvirt-api.xml to understand why this happens, but I couldn't locate the problem. [1] http://www.libvirt.org/html/libvirt-virterror.html [2] http://www.libvirt.org/html/libvirt-libvirt.html Matthias

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[libvirt] [PATCH v2] Support for qemu aio drive option
by Matthias Dahl 04 Jan '11

04 Jan '11

Revised patch against libvirt 0.7.6 to support qemu's aio option. qemu allows the user to choose what io storage api should be used, either the default (threads) or native (linux aio) which in the latter case can result in better performance. This patch exposes this functionality through libvirt. Thanks a lot to Eric Blake and Matthias Bolte for their comments. --- docs/formatdomain.html.in | 4 +++- docs/schemas/domain.rng | 13 +++++++++++-- src/conf/domain_conf.c | 23 +++++++++++++++++++++++ src/conf/domain_conf.h | 10 ++++++++++ src/qemu/qemu_conf.c | 14 ++++++++++++++ src/qemu/qemu_conf.h | 2 ++ 6 files changed, 63 insertions(+), 3 deletions(-) diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index ce49f7d..ec85ef3 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -478,7 +478,9 @@ attribute is the primary backend driver name, while the optional <code>type</code> attribute provides the sub-type. The optional <code>cache</code> attribute controls the cache mechanism, possible values are "default", "none", - "writethrough" and "writeback". <span class="since">Since 0.1.8</span> + "writethrough" and "writeback". Specific to KVM guests is the optional <code>aio</code> + attribute which controls what storage api is used for io operations, its possible + values are "threads" and "native". <span class="since">Since 0.1.8; "aio" attribute since 0.7.7</span> </dd> <dt><code>encryption</code></dt> <dd>If present, specifies how the volume is encrypted. See diff --git a/docs/schemas/domain.rng b/docs/schemas/domain.rng index bb6d00d..5d2dafe 100644 --- a/docs/schemas/domain.rng +++ b/docs/schemas/domain.rng @@ -499,8 +499,9 @@ <ref name="driverCache"/> </group> </choice> - <empty/> - </element> + <optional> + <ref name="driverAIO"/> + </optional> </define> <define name="driverFormat"> <attribute name="name"> @@ -521,6 +522,14 @@ </choice> </attribute> </define> + <define name="driverAIO"> + <attribute name="aio"> + <choice> + <value>threads</value> + <value>native</value> + </choice> + </attribute> + </define> <define name="controller"> <element name="controller"> <optional> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index 766993c..8bee7b8 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -120,6 +120,11 @@ VIR_ENUM_IMPL(virDomainDiskCache, VIR_DOMAIN_DISK_CACHE_LAST, "writethrough", "writeback") +VIR_ENUM_IMPL(virDomainDiskAIO, VIR_DOMAIN_DISK_AIO_LAST, + "default", + "native", + "threads") + VIR_ENUM_IMPL(virDomainController, VIR_DOMAIN_CONTROLLER_TYPE_LAST, "ide", "fdc", @@ -1228,6 +1233,7 @@ virDomainDiskDefParseXML(virConnectPtr conn, char *target = NULL; char *bus = NULL; char *cachetag = NULL; + char *aiotag = NULL; char *devaddr = NULL; virStorageEncryptionPtr encryption = NULL; char *serial = NULL; @@ -1293,6 +1299,7 @@ virDomainDiskDefParseXML(virConnectPtr conn, driverName = virXMLPropString(cur, "name"); driverType = virXMLPropString(cur, "type"); cachetag = virXMLPropString(cur, "cache"); + aiotag = virXMLPropString(cur, "aio"); } else if (xmlStrEqual(cur->name, BAD_CAST "readonly")) { def->readonly = 1; } else if (xmlStrEqual(cur->name, BAD_CAST "shareable")) { @@ -1409,6 +1416,13 @@ virDomainDiskDefParseXML(virConnectPtr conn, goto error; } + if (aiotag && + (def->aiomode = virDomainDiskAIOTypeFromString(aiotag)) < 0) { + virDomainReportError(conn, VIR_ERR_INTERNAL_ERROR, + _("unknown disk aio mode '%s'"), aiotag); + goto error; + } + if (devaddr) { if (sscanf(devaddr, "%x:%x:%x", &def->info.addr.pci.domain, @@ -1450,6 +1464,7 @@ cleanup: VIR_FREE(driverType); VIR_FREE(driverName); VIR_FREE(cachetag); + VIR_FREE(aiotag); VIR_FREE(devaddr); VIR_FREE(serial); virStorageEncryptionFree(encryption); @@ -4565,6 +4580,7 @@ virDomainDiskDefFormat(virConnectPtr conn, const char *device = virDomainDiskDeviceTypeToString(def->device); const char *bus = virDomainDiskBusTypeToString(def->bus); const char *cachemode = virDomainDiskCacheTypeToString(def->cachemode); + const char *aiomode = virDomainDiskAIOTypeToString(def->aiomode); if (!type) { virDomainReportError(conn, VIR_ERR_INTERNAL_ERROR, @@ -4586,6 +4602,11 @@ virDomainDiskDefFormat(virConnectPtr conn, _("unexpected disk cache mode %d"), def->cachemode); return -1; } + if (!aiomode) { + virDomainReportError(conn, VIR_ERR_INTERNAL_ERROR, + _("unexpected disk aio mode %d"), def->aiomode); + return -1; + } virBufferVSprintf(buf, " <disk type='%s' device='%s'>\n", @@ -4597,6 +4618,8 @@ virDomainDiskDefFormat(virConnectPtr conn, virBufferVSprintf(buf, " type='%s'", def->driverType); if (def->cachemode) virBufferVSprintf(buf, " cache='%s'", cachemode); + if (def->aiomode) + virBufferVSprintf(buf, " aio='%s'", aiomode); virBufferVSprintf(buf, "/>\n"); } diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h index 0b79e88..07805a6 100644 --- a/src/conf/domain_conf.h +++ b/src/conf/domain_conf.h @@ -141,6 +141,14 @@ enum virDomainDiskCache { VIR_DOMAIN_DISK_CACHE_LAST }; +enum virDomainDiskAIO { + VIR_DOMAIN_DISK_AIO_DEFAULT, + VIR_DOMAIN_DISK_AIO_NATIVE, + VIR_DOMAIN_DISK_AIO_THREADS, + + VIR_DOMAIN_DISK_AIO_LAST +}; + /* Stores the virtual disk configuration */ typedef struct _virDomainDiskDef virDomainDiskDef; typedef virDomainDiskDef *virDomainDiskDefPtr; @@ -154,6 +162,7 @@ struct _virDomainDiskDef { char *driverType; char *serial; int cachemode; + int aiomode; unsigned int readonly : 1; unsigned int shared : 1; virDomainDeviceInfo info; @@ -897,6 +906,7 @@ VIR_ENUM_DECL(virDomainDisk) VIR_ENUM_DECL(virDomainDiskDevice) VIR_ENUM_DECL(virDomainDiskBus) VIR_ENUM_DECL(virDomainDiskCache) +VIR_ENUM_DECL(virDomainDiskAIO) VIR_ENUM_DECL(virDomainController) VIR_ENUM_DECL(virDomainFS) VIR_ENUM_DECL(virDomainNet) diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c index 3d83a8f..fd3a670 100644 --- a/src/qemu/qemu_conf.c +++ b/src/qemu/qemu_conf.c @@ -83,6 +83,12 @@ VIR_ENUM_IMPL(qemuDiskCacheV2, VIR_DOMAIN_DISK_CACHE_LAST, "writethrough", "writeback"); +VIR_ENUM_DECL(qemuDiskAIO) +VIR_ENUM_IMPL(qemuDiskAIO, VIR_DOMAIN_DISK_AIO_LAST, + "default", + "native", + "threads"); + VIR_ENUM_DECL(qemuVideo) VIR_ENUM_IMPL(qemuVideo, VIR_DOMAIN_VIDEO_TYPE_LAST, @@ -1137,6 +1143,8 @@ static unsigned int qemudComputeCmdFlags(const char *help, flags |= QEMUD_CMD_FLAG_DRIVE_CACHE_V2; if (strstr(help, "format=")) flags |= QEMUD_CMD_FLAG_DRIVE_FORMAT; + if (strstr(help, "aio=threads|native")) + flags |= QEMUD_CMD_FLAG_DRIVE_AIO; } if (strstr(help, "-vga") && !strstr(help, "-std-vga")) flags |= QEMUD_CMD_FLAG_VGA; @@ -2340,6 +2348,12 @@ qemuBuildDriveStr(virDomainDiskDefPtr disk, virBufferAddLit(&opt, ",cache=off"); } + if (disk->aiomode && (qemuCmdFlags & QEMUD_CMD_FLAG_DRIVE_AIO)) { + const char * mode = qemuDiskAIOTypeToString(disk->aiomode); + + virBufferVSprintf(&opt, ",aio=%s", mode); + } + if (virBufferError(&opt)) { virReportOOMError(NULL); goto error; diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h index 101f187..780ae6e 100644 --- a/src/qemu/qemu_conf.h +++ b/src/qemu/qemu_conf.h @@ -82,6 +82,8 @@ enum qemud_cmd_flags { QEMUD_CMD_FLAG_SDL = (1 << 27), /* Is the new -sdl arg available */ QEMUD_CMD_FLAG_SMP_TOPOLOGY = (1 << 28), /* Is sockets=s,cores=c,threads=t available for -smp? */ QEMUD_CMD_FLAG_NETDEV = (1 << 29), /* The -netdev flag & netdev_add/remove monitor commands */ + + QEMUD_CMD_FLAG_DRIVE_AIO = (1 << 30), /* Is -drive aio= avail */ }; /* Main driver state */ -- 1.7.0.4

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[libvirt] ruby-libvirt issue
by Jaromír Červenka 24 Nov '10

24 Nov '10

Good evening, could anybody explain me this, please? divinus:~ # virsh error: cannot recv data: : Connection reset by peer error: failed to connect to the hypervisor divinus:~ # I am trying to imlement Chris's ruby-libvirt to my Ruby on Rails application. First few connection to libvirt daemon (thru ruby-libvirt API) from my app are ok, but then somethings happend and it's not possible to connect anymore until I restart libvirt daemon manually by init.d script or until I restart apache (or WEBrick). And it's not possible connect to virsh from shell also! See messages above. When I try ruby-libvirt from bare Ruby script, everythig is fine - doesn't matter how many times I connect. It's strange. Does anybody have experience with ruby-libvirt in RoR application? Thank you. Jaromir.

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