Re: [RFC] qemu: Check for changes in qemu modules directory

Hi All, Any comments on this RFC patch? Is this something we would like to see in the 6.7.0 release?

On 8/20/20 5:03 PM, Jim Fehlig wrote: > Add a configuration option for specifying location of the qemu modules > directory, defaulting to /usr/lib64/qemu. Then use this location to > check for changes in the directory, indicating that a qemu module has > changed and capabilities need to be reprobed. > > Signed-off-by: Jim Fehlig <jfehlig(a)suse.com&gt; > --- > > This is a mildly tested impl of the idea discussed here (and elsewhere > in the thread) > > https://www.redhat.com/archives/libvir-list/2020-August/msg00684.html > > I've checked that both system and session caches are updated when a > qemu modules package is updated. I'll do some more testing but wanted > to send the patch for early comments. Testing in other environments > would be much appreciated. Thanks! I've tried some more configurations and haven't noticed any problems with the patch thus far. The request for additional eyeballs and testing still valid though :-). Regards, Jim > > meson.build | 6 ++++++ > meson_options.txt | 1 + > src/qemu/qemu_capabilities.c | 35 +++++++++++++++++++++++++++++++++++ > 3 files changed, 42 insertions(+) > > diff --git a/meson.build b/meson.build > index a72d0c0e85..16928482aa 100644 > --- a/meson.build > +++ b/meson.build > @@ -1745,6 +1745,12 @@ if not get_option('driver_qemu').disabled() > if use_qemu > conf.set('WITH_QEMU', 1) > + qemu_moddir = get_option('qemu_moddir') > + if qemu_moddir == '' > + qemu_moddir = '/usr/lib64/qemu' > + endif > + conf.set_quoted('QEMU_MODDIR', qemu_moddir) > + > if host_machine.system() in ['freebsd', 'darwin'] > default_qemu_user = 'root' > default_qemu_group = 'wheel' > diff --git a/meson_options.txt b/meson_options.txt > index c538d323c1..cedbd79491 100644 > --- a/meson_options.txt > +++ b/meson_options.txt > @@ -59,6 +59,7 @@ option('driver_openvz', type: 'feature', value: 'auto', description: 'OpenVZ dri > option('driver_qemu', type: 'feature', value: 'auto', description: 'QEMU/KVM driver') > option('qemu_user', type: 'string', value: '', description: 'username to run QEMU system instance as') > option('qemu_group', type: 'string', value: '', description: 'groupname to run QEMU system instance as') > +option('qemu_moddir', type: 'string', value: '', description: 'set the directory where QEMU modules are located') > option('driver_remote', type: 'feature', value: 'enabled', description: 'remote driver') > option('remote_default_mode', type: 'combo', choices: ['legacy', 'direct'], value: 'legacy', description: 'remote driver default mode') > option('driver_secrets', type: 'feature', value: 'auto', description: 'local secrets management driver') > diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c > index ff6ba8c9e9..a00853c753 100644 > --- a/src/qemu/qemu_capabilities.c > +++ b/src/qemu/qemu_capabilities.c > @@ -677,6 +677,7 @@ struct _virQEMUCaps { > char *binary; > time_t ctime; > time_t libvirtCtime; > + time_t modDirMtime; > bool invalidation; > virBitmapPtr flags; > @@ -4194,6 +4195,7 @@ virQEMUCapsParseSEVInfo(virQEMUCapsPtr qemuCaps, xmlXPathContextPtr ctxt) > * <qemuCaps> > * <emulator>/some/path</emulator> > * <qemuctime>234235253</qemuctime> > + * <qemumoddirmtime>234235253</qemumoddirmtime> > * <selfctime>234235253</selfctime> > * <selfvers>1002016</selfvers> > * <flag name='foo'/> > @@ -4283,6 +4285,9 @@ virQEMUCapsLoadCache(virArch hostArch, > } > qemuCaps->ctime = (time_t)l; > + if (virXPathLongLong("string(./qemumoddirmtime)", ctxt, &l) == 0) > + qemuCaps->modDirMtime = (time_t)l; > + > if ((n = virXPathNodeSet("./flag", ctxt, &nodes)) < 0) { > virReportError(VIR_ERR_INTERNAL_ERROR, "%s", > _("failed to parse qemu capabilities flags")); > @@ -4615,6 +4620,10 @@ virQEMUCapsFormatCache(virQEMUCapsPtr qemuCaps) > qemuCaps->binary); > virBufferAsprintf(&buf, "<qemuctime>%llu</qemuctime>\n", > (long long)qemuCaps->ctime); > + if (qemuCaps->modDirMtime > 0) { > + virBufferAsprintf(&buf, "<qemumoddirmtime>%llu</qemumoddirmtime>\n", > + (long long)qemuCaps->modDirMtime); > + } > virBufferAsprintf(&buf, "<selfctime>%llu</selfctime>\n", > (long long)qemuCaps->libvirtCtime); > virBufferAsprintf(&buf, "<selfvers>%lu</selfvers>\n", > @@ -4881,6 +4890,23 @@ virQEMUCapsIsValid(void *data, > if (!qemuCaps->binary) > return true; > + if (virFileExists(QEMU_MODDIR)) { > + if (stat(QEMU_MODDIR, &sb) < 0) { > + VIR_DEBUG("Failed to stat QEMU module directory '%s': %s", > + QEMU_MODDIR, > + g_strerror(errno)); > + return false; > + } > + > + if (sb.st_mtime != qemuCaps->modDirMtime) { > + VIR_DEBUG("Outdated capabilities for '%s': QEMU modules " > + "directory '%s' changed (%lld vs %lld)", > + qemuCaps->binary, QEMU_MODDIR, > + (long long)sb.st_mtime, (long long)qemuCaps->modDirMtime); > + return false; > + } > + } > + > if (qemuCaps->libvirtCtime != virGetSelfLastChanged() || > qemuCaps->libvirtVersion != LIBVIR_VERSION_NUMBER) { > VIR_DEBUG("Outdated capabilities for '%s': libvirt changed " > @@ -5463,6 +5489,15 @@ virQEMUCapsNewForBinaryInternal(virArch hostArch, > goto error; > } > + if (virFileExists(QEMU_MODDIR)) { > + if (stat(QEMU_MODDIR, &sb) < 0) { > + virReportSystemError(errno, _("Cannot check QEMU module directory %s"), > + QEMU_MODDIR); > + goto error; > + } > + qemuCaps->modDirMtime = sb.st_mtime; > + } > + > if (virQEMUCapsInitQMP(qemuCaps, libDir, runUid, runGid) < 0) > goto error; >