March 2012 - Devel - libvirt List Archives

Re: [libvirt] Constantly changing USB product ID
by Avi Kivity 28 Mar '12

28 Mar '12

On 03/28/2012 02:41 PM, Avi Kivity wrote: > On 03/27/2012 05:48 PM, Jaap Winius wrote: > > Hi folks, > > > > Recently I learned how to configure KVM with USB pass-though > > functionality. In my case I configured my guest domain with this block > > of code: > > > > <hostdev mode='subsystem' type='usb' managed='yes'> > > <source> > > <vendor id='0x0c93'/> > > <product id='0x1772'/> > > <address bus='1' device='4'/> > > </source> > > </hostdev> > > > > At first this worked fine, but then later the guest domain refused to > > start because the USB device was absent. When I checked, I found that > > its product ID had mysteriously changed to 1771. Later it was back at > > 1772. Now it appears that the USB device I am dealing with has a > > product ID that changes back and forth between 1771 and 1772 at random. > > > > Apparently, the Windows program running on the guest domain is > > designed to deal with this nonsense, but the question is, Can KVM be > > configured to deal with it? Something like <product id='0x177*'/> > > would be useful, but that doesn't work. > > > > Any ideas would be much appreciated. > > > > This is really strange. What kind of device is this? > > I've filed an RFE [1] for virt-manager for assigning USB host devices > opportunistically, that is if they're plugged they're assigned, and if > not the guest starts without them. If it were implemented, you could > assign both 0x1771 and 0x1772 and whichever ID the device is today would > get assigned. > > > [1] https://bugzilla.redhat.com/show_bug.cgi?id=804432 > btw, the correct place for this discussion is likely the libvirt mailing list, or maybe the virt-manager list if it exists. -- error compiling committee.c: too many arguments to function

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[libvirt] Modern CPU models cannot be used with libvirt
by Jiri Denemark 28 Mar '12

28 Mar '12

Hi, Recently I realized that all modern CPU models defined in /etc/qemu/target-x86_64.conf are useless when qemu is used through libvirt. That's because we start qemu with -nodefconfig which results in qemu ignoring that file with CPU model definitions. We have a very good reason for using -nodefconfig because we need to control the ABI presented to a guest OS and we don't want any configuration file that can contain lots of things including device definitions to be read by qemu. However, we would really like the new CPU models to be understood by qemu even if used through libvirt. What would be the best way to solve this? I suspect this could have been already discussed in the past but obviously a workable solution was either not found or just not implemented. Jirka

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[libvirt] RFC: storage migration via pre-copy and streaming mirrors
by Eric Blake 28 Mar '12

28 Mar '12

This is the counter-proposal to my earlier RFC for storage migration via snapshot mirrors[1], resulting from a NACK on the code review for that earlier proposal[2]. In particular, this proposal fleshes out some of Paolo's design overview on the qemu wiki[3]. [1] https://www.redhat.com/archives/libvir-list/2012-March/msg00578.html [2] https://www.redhat.com/archives/libvir-list/2012-March/msg01033.html [3] http://wiki.qemu.org/Features/SnapshotsMultipleDevices My plan is to have everything in this RFC coded up in the next couple of days (hopefully no later than Thursday); this has missed the feature freeze for 0.9.11, so it should not be applied upstream until after the weekend release, as one of the first patches for 0.9.12. Backport-wise, the new flags can be backported as far back as the 0.9.10 .so API, but the new virDomainBlockCopy() API cannot be exported when doing a backport without breaking .so versions (although it's implemenation can be used internally). Additions ========= The following new error code will be added: VIR_ERR_BLOCK_COPY_IN_PROGRESS The following new API will be added: int virDomainBlockCopy(virDomainPtr dom, const char *disk, const char *base, const char *dest, const char *format, unsigned long bandwidth, unsigned int flags); The following new named values will be added: enum virDomainBlockJobType (used in virDomainBlockJobInfo): VIR_DOMAIN_BLOCK_JOB_TYPE_COPY = 2 The following new flags will be added: for virDomainBlockRebase: VIR_DOMAIN_BLOCK_REBASE_SHALLOW = 1 << 0 VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT = 1 << 1 VIR_DOMAIN_BLOCK_REBASE_COPY = 1 << 2 for virDomainBlockCopy: VIR_DOMAIN_BLOCK_COPY_SHALLOW = 1 << 0 VIR_DOMAIN_BLOCK_COPY_REUSE_EXT = 1 << 1 for virDomainBlockJobAbort: VIR_DOMAIN_BLOCK_JOB_ABORT_PIVOT Add some XML: Under //domain/drivers/disk, next to <source file='...'/>, add <mirror file='...'/> Semantics ========= virDomainBlockCopy sets up a BLOCK_JOB_TYPE_COPY job. 'disk' names the disk to be copied (can be 'vda' or '/path/to/source', as with other block commands) and must not be NULL. 'base' names the path to the backing file in the chain of the source that will be the new backing file of the destination; if this parameter is NULL, then the destination file defaults to a complete block pull, but the COPY_SHALLOW flag instead requests a pull of just the top file in the source backing chain. 'dest' names the copy being created and must not be NULL; normally, this file is created by the hypervisor/libvirt, but the COPY_REUSE_EXT flag lets an application pass in a pre-created file (allowing metadata to include a relative instead of absolute backing file name). 'format' gives the format of the copy, or NULL to either probe the format of a COPY_REUSE_EXT dest or to reuse the same format as the source. flags cannot contain COPY_SHALLOW unless 'base' is NULL. Once a block copy job is started, calls to virDomainGetBlockJobInfo() for the same 'disk' will report an info with VIR_DOMAIN_BLOCK_JOB_TYPE_COPY as the type. This job never completes on its own, but must be stopped by the user (this enables mirroring to continue until the user informs libvirt that any backing files, perhaps located at different locations as specified by relative path names using REUSE_EXT, have been externally copied into place). There are two phases to a TYPE_COPY job. In the first phase, cur < end when querying progress, calls to virDomainBlockJobAbort(dom, disk, 0) will cancel the operation and revert to the source, and calls to virDomainBlockJobAbort(dom, disk, VIR_DOMAIN_BLOCK_JOB_ABORT_PIVOT) will fail with VIR_ERR_BLOCK_COPY_IN_PROGRESS. In the second phase, cur == end when querying progress, calls to virDomainBlockJobAbort(dom, disk, 0) will break the mirroring and revert to the source, while calls to virDomainBlockJobAbort(dom, disk, VIR_DOMAIN_BLOCK_JOB_ABORT_PIVOT) will break the mirroring and pivot to the destination. Use of VIR_DOMAIN_BLOCK_JOB_ABORT_PIVOT on a non-copy block job will fail with VIR_ERR_INVALID_ARG. virDomainBlockRebase(dom, disk, dest, bandwidth, VIR_DOMAIN_BLOCK_REBASE_COPY | (flags & 3)) is shorthand for virDomainBlockCopy(dom, disk, NULL, dest, NULL, bandwidth, (flags & 3)) - that is, use of the REBASE_COPY flag treats the BlockRebase 'base' argument as the BlockCopy 'dest' argument, creates the destination with the same file format as the source (or probes the backing file format if REBASE_REUSE_EXT is used), and passes the COPY_SHALLOW and COPY_REUSE_EXT flags through (note that the similarly named flags were conveniently chosen to be the same values). Attempts to use REBASE_SHALLOW or REBASE_REUSE_EXT without also using REBASE_COPY will fail with VIR_ERR_INVALID_ARG. While a copy operation is in place, virDomainGetXMLDesc (dumpxml) will show the <mirror> element for that <disk>. Initial Implementation ====================== When virDomainBlockCopy is called (perhaps via the virDomainBlockRebase alias), it first sets up a mirror using the 'drive-mirror' monitor command and the destination file name. The mirror is opened with the 'existing' mode if _REUSE_EXT is present; otherwise it is opened with the 'absolute-paths' mode if _SHALLOW is present or 'no-backing-file' mode if no flags are present. Next, the function calls the 'block_stream' monitor command to start the streaming. The streaming command uses 'base' as its starting point, except that when _SHALLOW was specified, libvirt will use the backing file of the source disk, rather than NULL (this can be obtained by the 'query-block' monitor command; although someday libvirt should start tracking this information in <domain> XML rather than relying on qemu). At this point, control returns to the user, and the stream proceeds in the background; virDomainBlockJobSetSpeed can tune the speed of the block streaming. At least in the initial implementation, as long as the block job is active, libvirt will prevent 'virDomainMigrate', 'virDomainSave', 'virDomainSnapshotCreateXML' in general, and 'virDomainDetachDevice' of the disk being mirrored, all with the new VIR_ERR_BLOCK_COPY_IN_PROGRESS error. This is because I don't have an easy way to resume mirroring when restarting a new qemu process; preventing these actions until the user first cancels the ongoing mirroring will result in fewer corner cases that libvirt has to worry about. This also implies that the initial implementation will fail for persistent domains, and only be useful for transient domains. Attempts to define a domain with a <mirror> element are rejected, leaving <mirror> as output-only XML useful in restoring state when restarting libvirtd. It may be possible to add persistent support in the future, once we determine how to make qemu resume a mirrored block device; at that point, it would be possible to specify <mirror> in domain xml during domain creation or during device hotplug. When the block stream finishes, qemu will send an event to libvirt (libvirt will also have to manually check for completion on a libvirtd restart, based on whether cur == end in the block job info). I'm not yet sure whether to expose this event to the user so that they do not have to poll the block job info, or whether to consume it internally. At any rate, before this event occurs, the BLOCK_JOB_ABORT_PIVOT flag is rejected, and virDomainBlockJobAbort without flags uses the 'block_job_cancel' monitor command to stop the streaming early, then the 'drive-reopen' monitor command to break the mirroring back to the source; it is feasible that there is a race where a 'block_job_cancel' can be called after the pull is complete but before the completion event has been processed, so the code must proceed on to the 'drive-reopen' even if the job cancel fails. After the event occurs, virDomainBlockJobAbort only needs to use the 'drive-reopen' monitor command, with either the source or the destination file depending on the BLOCK_JOB_ABORT_PIVOT flag. Until 'drive-reopen' is made atomic in qemu (by adding code to support it inside 'transaction'), the user risks a block job abort rendering the disk unusable, because the source was closed before the destination was opened; hopefully this situation is rare, in part because libvirt will do stat() checks and SELinux labeling on destination files before starting qemu monitor commands, as a sanity check that qemu will be able to use the specified files. If qemu ever adds atomic 'drive-reopen' support, we can add a new flag BLOCK_JOB_ABORT_ATOMIC that fails on older qemu, and ensures the use of 'transaction' on the newer qemu that supports an atomic reopen. If a block mirror is aborted (whether by the user calling virDomainBlockJobAbort with no flag, or by the qemu process ending due to things like a guest-initiated shutdown), then the mirror can be safely discarded, and restarting the domain will be unmirrored where the virDomainBlockRebase can be called again from scratch. Examples ======== For some examples, starting with base <- snap1 <- snap2 <- snap3 as the backing chain for disk 'vda', virDomainBlockCopy(dom, "vda", NULL, "/path/to/copy", NULL, 0) would set up a job that results in /path/to/copy being the same file format as snap3, but containing the entire chain virDomainBlockCopy(dom, "vda", "/path/to/snap1", "/path/to/copy", "qed", 0) would set up a job that results in base <- snap1 <- copy as the mirrored backing chain, and ensuring that copy is formatted as qed regardless of the format of snap3 virDomainBlockCopy(dom, "vda", NULL, "/path/to/copy", NULL, VIR_DOMAIN_BLOCK_COPY_SHALLOW) is shorthand for virDomainBlockCopy(dom, "vda", "/path/to/snap2", "/path/to/copy", NULL, 0) and results in base <- snap1 <- snap2 <- copy creates copy using the same format as snap3 virDomainBlockCopy(dom, "vda", "/path/to/snap2", "/path/to/copy", NULL, VIR_DOMAIN_BLOCK_COPY_REUSE_EXT) requires /path/to/copy to already exist, probes it for existing format (which might be different from snap3), and proceeds to mirror everything so that snap2 is the base of copy (and the user is at fault if the pre-existing file doesn't call out a backing file that happens to be identical in content to snap2) oVirt will probably use the sequence: - use qemu-img to create an empty qcow2 file with relative backing name to the destination storage - call virDomainBlockRebase(dom, disk, "/path/to/copy", VIR_DOMAIN_BLOCK_REBASE_COPY | VIR_DOMAIN_BLOCK_REBASE_SHALLOW | VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT) - copy the base files from source to destination storage (this can be done in parallel, either before or after the virDomainBlockRebase call) - wait for the block pull to finish (either by waiting for an event if I propagate the event, or by polling virDomainBlockJobInfo, or even by polling virDomainBlockJobAbort(VIR_DOMAIN_BLOCK_JOB_ABORT_PIVOT) and checking for VIR_ERR_BLOCK_COPY_IN_PROGRESS - once both the base files are in place and the block pull half of the copy job is complete (and without regard to whether the block stream or the external base file copying completed first), call virDomainBlockJobAbort(,VIR_DOMAIN_BLOCK_JOB_ABORT_PIVOT) to reopen to the new storage domain chain Comparison to first RFC ======================= This proposal exposes only one disk at a time, while the earlier virDomainSnapshotCreateXML <mirror> approach could atomically set up mirroring on multiple disks. However, the nature of block jobs being a background process means that parallel jobs can be run on independent disks, so the user can do the overall block migration with the time cost of the slowest disk, rather than having to do things serially with the time cost of all disks added together. This proposal avoids having to create an intermediate snapshot, so the pull is more efficient and the source chain does not get longer, no matter how many times the process is aborted and restarted. This proposal can expose the no-backing-file mode, while the snapshot approach did not. To survive across libvirtd restarts, the snapshot approach was using <domainsnapshot> to store the mirroring status in a user-visible location; this approach has to modify the internal live xml (alongside other internal data, such as the qemu pid). Or perhaps I can add a <mirror> subelement to <disk> of a domain and make it user-visible after all, and treat that as an output-only parameter for now. Both approaches face the dilemma of how to start a new qemu process with mirroring intact, and my solution in both patch series will be to prevent any action that would force libvirt to save domain state until after the user has first canceled all current mirroring jobs. This limitation is not permanent - if future qemu provides better ways to restart mirroring, and as libvirt is taught to store the full backing chain in <domain> xml instead of probing it on the fly, we can relax this restriction in the future. -- Eric Blake eblake(a)redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org

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[libvirt] libvirt starts QEMU with bad CPU based on its XML
by Doug Goldstein 28 Mar '12

28 Mar '12

My XML configs for my VM machines have it set to AMD Opteron G3s, but libvirt is creating QEMU with a core2duo. This is not correct at all. I've included the setup and config of one machine that does this. But another machine that does this matches danpb's AMD Quad Core Dual NUMA system he posted on the mailing list recently. That machine is using a stock qemu-0.15.1 from upstream's git and libvirt git a few commits shy of the 0.9.11 rc1. The machine below is using libvirt 0.9.10 and qemu-kvm-1.0. Here's the setup: The host is: processor : 63 vendor_id : AuthenticAMD cpu family : 21 model : 1 model name : AMD Opteron(TM) Processor 6272 stepping : 2 microcode : 0x6000613 cpu MHz : 2099.875 cache size : 2048 KB physical id : 2 siblings : 16 core id : 7 cpu cores : 8 apicid : 79 initial apicid : 79 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc extd_apicid amd_dcm aperfmperf pni pclmulqdq monitor ssse3 cx16 sse4_1 sse4_2 popcnt aes xsave avx lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs xop skinit wdt lwp fma4 nodeid_msr topoext perfctr_core arat cpb npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold bogomips : 4200.08 TLB size : 1536 4K pages clflush size : 64 cache_alignment : 64 address sizes : 48 bits physical, 48 bits virtual power management: ts ttp tm 100mhzsteps hwpstate [9] The guest is: processor : 1 vendor_id : AuthenticAMD cpu family : 6 model : 15 model name : Intel(R) Core(TM)2 Duo CPU T7700 @ 2.40GHz stepping : 11 cpu MHz : 2100.397 cache size : 512 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 10 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext fxsr_opt pdpe1gb lm pni cx16 popcnt lahf_lm cmp_legacy svm cr8legacy abm sse4a misalignsse 3dnowprefetch bogomips : 4200.01 The QEMU command line contains the following: -cpu core2duo,+wdt,+skinit,+osvw,+3dnowprefetch,+misalignsse,+sse4a,+abm,+cr8legacy,+extapic,+svm,+cmp_legacy,+lahf_lm,+rdtscp,+pdpe1gb,+fxsr_opt,+mmxext,+aes,+popcnt,+sse4.2,+sse4.1,+cx16,+ht While libvirt's XML contains: <cpu match='exact'> <model>Opteron_G3</model> <vendor>AMD</vendor> <feature policy='require' name='aes'/> <feature policy='require' name='skinit'/> <feature policy='require' name='vme'/> <feature policy='require' name='mmxext'/> <feature policy='require' name='fxsr_opt'/> <feature policy='require' name='cr8legacy'/> <feature policy='require' name='ht'/> <feature policy='require' name='3dnowprefetch'/> <feature policy='require' name='ssse3'/> <feature policy='require' name='wdt'/> <feature policy='require' name='extapic'/> <feature policy='require' name='pdpe1gb'/> <feature policy='require' name='osvw'/> <feature policy='require' name='sse4.1'/> <feature policy='require' name='cmp_legacy'/> <feature policy='require' name='sse4.2'/> </cpu> -- Doug Goldstein

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[libvirt] [PATCH] virsh: plug memory leaks on failure path
by Alex Jia 28 Mar '12

28 Mar '12

Leaks are introduced in commit 1cf0e3d and fe383bb. * tools/virsh.c (cmdSnapshotList): fix memory leaks. * How to reproduce? % virsh snapshot-list foo --parent --roots error: --parent and --roots are mutually exclusive error: Failed to disconnect from the hypervisor, 1 leaked reference(s) % virsh snapshot-list foo --parent --tree error: --parent and --tree are mutually exclusive error: Failed to disconnect from the hypervisor, 1 leaked reference(s) % virsh snapshot-list foo --roots --tree error: --roots and --tree are mutually exclusive error: Failed to disconnect from the hypervisor, 1 leaked reference(s) ...... Signed-off-by: Alex Jia <ajia(a)redhat.com> --- tools/virsh.c | 5 +++++ 1 files changed, 5 insertions(+), 0 deletions(-) diff --git a/tools/virsh.c b/tools/virsh.c index 5009b6b..f5c3b60 100644 --- a/tools/virsh.c +++ b/tools/virsh.c @@ -16357,11 +16357,13 @@ cmdSnapshotList(vshControl *ctl, const vshCmd *cmd) if (vshCommandOptBool(cmd, "roots")) { vshError(ctl, "%s", _("--parent and --roots are mutually exclusive")); + virDomainFree(dom); return false; } if (tree) { vshError(ctl, "%s", _("--parent and --tree are mutually exclusive")); + virDomainFree(dom); return false; } parent_filter = 1; @@ -16369,11 +16371,13 @@ cmdSnapshotList(vshControl *ctl, const vshCmd *cmd) if (tree) { vshError(ctl, "%s", _("--roots and --tree are mutually exclusive")); + virDomainFree(dom); return false; } if (from) { vshError(ctl, "%s", _("--roots and --from are mutually exclusive")); + virDomainFree(dom); } flags |= VIR_DOMAIN_SNAPSHOT_LIST_ROOTS; } @@ -16381,6 +16385,7 @@ cmdSnapshotList(vshControl *ctl, const vshCmd *cmd) if (tree) { vshError(ctl, "%s", _("--leaves and --tree are mutually exclusive")); + virDomainFree(dom); return false; } flags |= VIR_DOMAIN_SNAPSHOT_LIST_LEAVES; -- 1.7.1

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[libvirt] [PATCH] virsh: add error return value
by Alex Jia 28 Mar '12

28 Mar '12

* tools/virsh.c (cmdSnapshotList): Avoiding to continue to execute subsequent codes, the programming should return false when meeting a error. For details, please see the following link: RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=807545 Signed-off-by: Alex Jia <ajia(a)redhat.com> --- tools/virsh.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/tools/virsh.c b/tools/virsh.c index 5009b6b..7e74744 100644 --- a/tools/virsh.c +++ b/tools/virsh.c @@ -16374,6 +16374,7 @@ cmdSnapshotList(vshControl *ctl, const vshCmd *cmd) if (from) { vshError(ctl, "%s", _("--roots and --from are mutually exclusive")); + return false; } flags |= VIR_DOMAIN_SNAPSHOT_LIST_ROOTS; } -- 1.7.1

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[libvirt] Coverity automatic detection
by Alex Jia 28 Mar '12

28 Mar '12

This email is automatically generated. The test result is based on the following git commit: 851117b Enable all warnings permanently & default to -Werror for GIT builds Analysis summary report: ------------------------ Files analyzed : 306 Total LoC input to cov-analyze : 362576 Functions analyzed : 8807 Paths analyzed : 1075505 Defect occurrences found : 105 Total 7 ATOMICITY 15 CHECKED_RETURN 14 DEADCODE 1 EVALUATION_ORDER 9 FORWARD_NULL 13 LOCK 3 NEGATIVE_RETURNS 1 NO_EFFECT 3 NULL_RETURNS 1 OVERRUN_STATIC 16 RESOURCE_LEAK 1 RETURN_LOCAL 12 REVERSE_INULL 1 SIZEOF_MISMATCH 6 UNINIT 2 UNUSED_VALUE Exceeded path limit of 5000 paths in 0.55% of functions (normally up to 5% of functions encounter this limitation) For details, please see attachment. Regards, Alex

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[libvirt] [PATCH] snapshot: fix virsh docs
by Eric Blake 28 Mar '12

28 Mar '12

Commit d42a2ff forgot to touch up virsh documentation, and commit 4e9953a mis-spelled the option name. * tools/virsh.pod (snapshot-create, snapshot-create-as): Fix typo and match recent change in flag meaning. --- tools/virsh.pod | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) diff --git a/tools/virsh.pod b/tools/virsh.pod index 390bcec..76d2ea4 100644 --- a/tools/virsh.pod +++ b/tools/virsh.pod @@ -2347,7 +2347,7 @@ metadata again). If I<--reuse-external> is specified, and the snapshot XML requests an external snapshot with a destination of an existing file, then the -existing file is truncated and reused; otherwise, a snapshot is refused +destination must exist, and is reused; otherwise, a snapshot is refused to avoid losing contents of the existing files. If I<--quiesce> is specified, libvirt will try to use guest agent @@ -2367,7 +2367,7 @@ metadata is silently lost when the domain quits running (whether by command such as B<destroy> or by internal guest action). =item B<snapshot-create-as> I<domain> {[I<--print-xml>] -| [I<--no-metadata>] [I<--halt>] [I<--reuse-existing>]} [I<name>] +| [I<--no-metadata>] [I<--halt>] [I<--reuse-external>]} [I<name>] [I<description>] [I<--disk-only> [I<--quiesce>] [I<--atomic>] [[I<--diskspec>] B<diskspec>]...] @@ -2394,7 +2394,7 @@ results in the following XML: If I<--reuse-external> is specified, and the domain XML or I<diskspec> option requests an external snapshot with a destination of an existing -file, then the existing file is truncated and reused; otherwise, a +file, then the destination must exist, and is reused; otherwise, a snapshot is refused to avoid losing contents of the existing files. If I<--quiesce> is specified, libvirt will try to use guest agent -- 1.7.7.6

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[libvirt] Turning off libvirtd mdns by default
by Stef Walter 27 Mar '12

27 Mar '12

In the GNOME UI we'd like to make use of Avahi discovery and name resolution "out of the box". A typical use case is for discovery of printers that are advertised using MDNS. This should work even on potentially 'hostile' networks such as a wireless access point in a print shop or airport. It should work without user configuration. https://fedoraproject.org/wiki/Desktop/Whiteboards/AvahiDefault In order to turn on Avahi by default, and make it work by default, we'd like to make it possible to use Avahi without advertising any information to the network by default. Advertising information to the network (even the host name) without the user's configuration or consent is a privacy issue. libvirtd advertises itself via MDNS on the network by default. I understand that MDNS discovery of libvirtd is really handy in many cases. However since one has to configure network access in libvirtd anyway -- none of the access methods work "out of the box" to my understanding -- I'd like to suggest turning off libvirtd's MDNS publishing by default. As part of setting up libvirtd for network access, the user would turn on mdns_adv. I hope that makes sense. Let me know if I've gotten something wrong. Would you accept a patch to do this? Or would you suggest that we try and do this downstream in the Fedora/RHEL packages instead? Cheers, Stef

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[libvirt] [PATCH] qemu: Make migration fail when port profile association fails on the dst host
by Christian Benvenuti (benve) 27 Mar '12

27 Mar '12

In the current V3 migration protocol, Libvirt does not check the result of the function qemuMigrationVPAssociatePortProfiles This means that it is possible for a migration to complete successfully even when the VM loses network connectivity on the destination host. With this change libvirt aborts the migration (during the "finish" step) when the above function fails, that is to say when at least one of the port profile associations fails. Signed-off by: Christian Benvenuti <benve(a)cisco.com> --- src/qemu/qemu_migration.c | 24 ++++++++++++++++++++---- 1 files changed, 16 insertions(+), 4 deletions(-) diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c index 802785f..38fbf83 100644 --- a/src/qemu/qemu_migration.c +++ b/src/qemu/qemu_migration.c @@ -2716,7 +2716,7 @@ qemuMigrationPerform(struct qemud_driver *driver, } } -static void +static int qemuMigrationVPAssociatePortProfiles(virDomainDefPtr def) { int i; int last_good_net = -1; @@ -2731,13 +2731,17 @@ qemuMigrationVPAssociatePortProfiles(virDomainDefPtr def) { virDomainNetGetActualDirectDev(net), -1, def->uuid, - VIR_NETDEV_VPORT_PROFILE_OP_MIGRATE_IN_FINISH, false) < 0) + VIR_NETDEV_VPORT_PROFILE_OP_MIGRATE_IN_FINISH, + false) < 0) { + VIR_ERROR("Port profile Associate failed for %s", net->ifname); goto err_exit; + } + VIR_DEBUG("Port profile Associate succeeded for %s", net->ifname); } last_good_net = i; } - return; + return 0; err_exit: for (i = 0; i < last_good_net; i++) { @@ -2751,6 +2755,7 @@ err_exit: VIR_NETDEV_VPORT_PROFILE_OP_MIGRATE_IN_FINISH)); } } + return -1; } @@ -2805,7 +2810,18 @@ qemuMigrationFinish(struct qemud_driver *driver, goto endjob; } - qemuMigrationVPAssociatePortProfiles(vm->def); + if (qemuMigrationVPAssociatePortProfiles(vm->def) < 0) { + qemuProcessStop(driver, vm, 1, VIR_DOMAIN_SHUTOFF_FAILED); + virDomainAuditStop(vm, "failed"); + event = virDomainEventNewFromObj(vm, + VIR_DOMAIN_EVENT_STOPPED, + VIR_DOMAIN_EVENT_STOPPED_FAILED); + goto endjob; + } if (flags & VIR_MIGRATE_PERSIST_DEST) { virDomainDefPtr vmdef; -- 1.7.1

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