Re: [libvirt] [REPOSTv2 PATCH v3 1/6] conf: Add VM Generation ID parse/format support

On 05/17/2018 02:42 PM, John Ferlan wrote: > The VM Generation ID is a mechanism to provide a unique 128-bit, > cryptographically random, and integer value identifier known as > the GUID (Globally Unique Identifier) to the guest OS. The value > is used to help notify the guest operating system when the virtual > machine is executed with a different configuration. > > This patch adds support for a new "genid" XML element similar to > the "uuid" element. The "genid" element can have two forms "<genid/>" > or "<genid>$GUID</genid>". If the $GUID is not provided, libvirt > will generate one and save it in the XML. > > Since adding support for a generated GUID (or UUID like) value to > be displayed modifying the xml2xml test to include virrandommock.so > is necessary since it will generate a "known" value. > > Signed-off-by: John Ferlan <jferlan(a)redhat.com&gt; > --- > docs/formatdomain.html.in | 27 ++++++++++++ > docs/schemas/domaincommon.rng | 8 ++++ > src/conf/domain_conf.c | 54 ++++++++++++++++++++++++ > src/conf/domain_conf.h | 5 +++ > tests/qemuxml2argvdata/genid-auto.xml | 32 ++++++++++++++ > tests/qemuxml2argvdata/genid.xml | 32 ++++++++++++++ > tests/qemuxml2xmloutdata/genid-active.xml | 32 ++++++++++++++ > tests/qemuxml2xmloutdata/genid-auto-active.xml | 32 ++++++++++++++ > tests/qemuxml2xmloutdata/genid-auto-inactive.xml | 32 ++++++++++++++ > tests/qemuxml2xmloutdata/genid-inactive.xml | 32 ++++++++++++++ > tests/qemuxml2xmltest.c | 5 ++- > 11 files changed, 290 insertions(+), 1 deletion(-) > create mode 100644 tests/qemuxml2argvdata/genid-auto.xml > create mode 100644 tests/qemuxml2argvdata/genid.xml > create mode 100644 tests/qemuxml2xmloutdata/genid-active.xml > create mode 100644 tests/qemuxml2xmloutdata/genid-auto-active.xml > create mode 100644 tests/qemuxml2xmloutdata/genid-auto-inactive.xml > create mode 100644 tests/qemuxml2xmloutdata/genid-inactive.xml > > diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in > index 0d0fd3b9f3..72a55ff075 100644 > --- a/docs/formatdomain.html.in > +++ b/docs/formatdomain.html.in > @@ -34,6 +34,7 @@ > &lt;domain type='kvm' id='1'&gt; > &lt;name&gt;MyGuest&lt;/name&gt; > &lt;uuid&gt;4dea22b3-1d52-d8f3-2516-782e98ab3fa0&lt;/uuid&gt; > + &lt;genid&gt;43dc0cf8-809b-4adb-9bea-a9abb5f3d90e&lt;/genid&gt; > &lt;title&gt;A short description - title - of the domain&lt;/title&gt; > &lt;description&gt;Some human readable description&lt;/description&gt; > &lt;metadata&gt; > @@ -61,6 +62,32 @@ > specification. <span class="since">Since 0.0.1, sysinfo > since 0.8.7</span></dd> > > + <dt><code>genid</code></dt> > + <dd><span class="since">Since 4.4.0</span>, the <code>genid</code> > + element can be used to add a Virtual Machine Generation ID which > + exposes a 128-bit, cryptographically random, integer value identifier, > + referred to as a Globally Unique Identifier (GUID) using the same > + format as the <code>uuid</code>. The value is used to help notify > + the guest operating system when the virtual machine is re-executing > + something that has already executed before, such as: > + > + <ul> > + <li>VM starts executing a snapshot</li> > + <li>VM is recovered from backup</li> > + <li>VM is failover in a disaster recovery environment</li> > + <li>VM is imported, copied, or cloned</li> > + </ul> > + > + The guest operating system notices the change and is then able to > + react as appropriate by marking its copies of distributed databases > + as dirty, re-initializing its random number generator, etc. > + > + <p> > + The libvirt XML parser will accept both a provided GUID value > + or just &lt;genid/&gt; in which case a GUID will be generated > + and saved in the XML. For the transitions such as above, libvirt > + will change the GUID before re-executing.</p></dd> > + > <dt><code>title</code></dt> > <dd>The optional element <code>title</code> provides space for a > short description of the domain. The title should not contain > diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng > index 71ac3d079c..1fba108927 100644 > --- a/docs/schemas/domaincommon.rng > +++ b/docs/schemas/domaincommon.rng > @@ -502,6 +502,14 @@ > <ref name="UUID"/> > </element> > </optional> > + <optional> > + <element name="genid"> > + <choice> > + <ref name="UUID"/> > + <empty/> > + </choice> > + </element> > + </optional> > </interleave> > </define> > <define name="idmap"> > diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c > index 3689ac0a82..4d5f3c6740 100644 > --- a/src/conf/domain_conf.c > +++ b/src/conf/domain_conf.c > @@ -18919,6 +18919,34 @@ virDomainDefParseXML(xmlDocPtr xml, > VIR_FREE(tmp); > } > > + /* Extract domain genid - a genid can either be provided or generated */ > + if ((n = virXPathNodeSet("./genid", ctxt, &nodes)) < 0) > + goto error; > + > + if (n > 0) { > + if (n != 1) { > + virReportError(VIR_ERR_XML_ERROR, "%s", > + _("element 'genid' can only appear once")); This _() seems misaligned.

> + goto error; > + } > + def->genidRequested = true; > + if (!(tmp = virXPathString("string(./genid[1])", ctxt))) { Since you check that there's only onde <genid/> above, this [1] seems redundant.

> + if (virUUIDGenerate(def->genid) < 0) { > + virReportError(VIR_ERR_INTERNAL_ERROR, > + "%s", _("Failed to generate genid")); > + goto error; > + } > + def->genidGenerated = true; > + } else { > + if (virUUIDParse(tmp, def->genid) < 0) { > + virReportError(VIR_ERR_INTERNAL_ERROR, > + "%s", _("malformed genid element")); > + goto error; > + } > + } > + } > + VIR_FREE(nodes); > + Michal