Re: [PATCH] virsh: Introduce new hypervisor-cpu-models command

On a Thursday in 2025, Collin Walling wrote: > From: David Judkovics <djudkovi(a)linux.ibm.com> > > Add new virsh command 'hypervisor-cpu-models'. Command pulls from the > existing domcapabilities XML and uses xpath to parse CPU model strings. > By default, only models reported as usable by the hypervisor on the > host system are printed. User may specify "--all" to also print > models which are not supported on the host. > > Signed-off-by: David Judkovics <djudkovi(a)linux.ibm.com&gt; > Signed-off-by: Boris Fiuczynski <fiuczy(a)linux.ibm.com&gt; > Signed-off-by: Collin Walling <walling(a)linux.ibm.com&gt; > --- > > This is a continuation of a previous series found here: > > https://lists.libvirt.org/archives/list/devel@lists.libvirt.org/message/I... > > --- > docs/manpages/virsh.rst | 24 +++++++++++++ > tools/virsh-host.c | 74 +++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 98 insertions(+) > > diff --git a/docs/manpages/virsh.rst b/docs/manpages/virsh.rst > index baced15dec..48b667736d 100644 > --- a/docs/manpages/virsh.rst > +++ b/docs/manpages/virsh.rst > @@ -1034,6 +1034,30 @@ listed in the XML description. If *--migratable* is specified, features that > block migration will not be included in the resulting CPU. > > > +hypervisor-cpu-models > +--------------------- > + > +**Syntax:** > + > +:: > + > + hypervisor-cpu-models [virttype] [emulator] [arch] [machine] [--all] > + The actualy syntax for this (as reported by virsh hypervisor-cpu-models --help) is: hypervisor-cpu-models [--virttype <string>] [--emulator <string>] [--arch <string>] [--machine <string>] [--all] i.e. specifying the option name is mandatory

> +Print the list of CPU models known by the hypervisor for the specified architecture. > +It is not guaranteed that a listed CPU will run on the host. To determine CPU > +model compatibility with the host, see ``virsh hypervisor-cpu-baseline`` and > +``virsh hypervisor-cpu-compare``. > + > +The *virttype* option specifies the virtualization type (usable in the 'type' > +attribute of the <domain> top level element from the domain XML). *emulator* > +specifies the path to the emulator, *arch* specifies the CPU architecture, and > +*machine* specifies the machine type. > + > +By default, only the models that are claimed to be "usable" by the hypervisor > +on the host are reported. The option *--all* will report every CPU model known > +to the hypervisor, including ones that are not supported on the hypervisor (e.g. > +newer generation models). > + > DOMAIN COMMANDS > =============== > > diff --git a/tools/virsh-host.c b/tools/virsh-host.c > index 9e8f542c96..2884067bbb 100644 > --- a/tools/virsh-host.c > +++ b/tools/virsh-host.c > @@ -1766,6 +1766,74 @@ cmdHypervisorCPUBaseline(vshControl *ctl, > } > > > +/* > + * "hypervisor-cpu-models" command > + */ > +static const vshCmdInfo info_hypervisor_cpu_models = { > + .help = N_("Hypervisor reported CPU models"), > + .desc = N_("Get the CPU models reported by the hypervisor."), > +}; > + > +static const vshCmdOptDef opts_hypervisor_cpu_models[] = { > + {.name = "virttype", > + .type = VSH_OT_STRING, > + .completer = virshDomainVirtTypeCompleter, > + .help = N_("virtualization type (/domain/@type)"), > + }, > + {.name = "emulator", > + .type = VSH_OT_STRING, > + .unwanted_positional = true, The use of this option is discouraged, see: commit a67f737ddfc59b0f5b3905bd1c0935ced82de3d0 Author: Peter Krempa <pkrempa(a)redhat.com&gt; AuthorDate: 2024-03-14 17:17:19 +0100 Commit: Peter Krempa <pkrempa(a)redhat.com&gt; CommitDate: 2024-04-02 14:24:30 +0200 virt-admin: Annodate 'unwanted_positional' arguments https://gitlab.com/libvirt/libvirt/-/commit/a67f737ddfc59b0f5b3905bd1c093...

> + .help = N_("path to emulator binary (/domain/devices/emulator)"), > + }, > + {.name = "arch", > + .type = VSH_OT_STRING, > + .completer = virshArchCompleter, > + .help = N_("CPU architecture (/domain/os/type/@arch)"), > + }, > + {.name = "machine", > + .type = VSH_OT_STRING, > + .help = N_("machine type (/domain/os/type/@machine)"), > + }, > + {.name = "all", > + .type = VSH_OT_BOOL, > + .help = N_("include all CPU models known to the hypervisor for the architecture") > + }, > + {.name = NULL} > +}; > + > +static bool > +cmdHypervisorCPUModelNames(vshControl *ctl, > + const vshCmd *cmd) > +{ > + g_autofree char *caps_xml = NULL; > + const char *virttype = NULL; > + const char *emulator = NULL; > + const char *arch = NULL; > + const char *machine = NULL; > + const char *xpath_all = "//cpu//model[@usable]/text()"; > + const char *xpath_usable = "//cpu//model[@usable='yes']/text()"; > + virshControl *priv = ctl->privData; > + if (vshCommandOptBool(cmd, "all")) xpath = "//cpu//model[@usable]/text()"; else xpath = "//cpu//model[@usable='yes']/text()"; gets rid of the ternary operator and groups the command line processing together.

> + if (vshCommandOptString(ctl, cmd, "virttype", &virttype) < 0 || > + vshCommandOptString(ctl, cmd, "emulator", &emulator) < 0 || > + vshCommandOptString(ctl, cmd, "arch", &arch) < 0 || > + vshCommandOptString(ctl, cmd, "machine", &machine) < 0) > + return false; > + > + caps_xml = virConnectGetDomainCapabilities(priv->conn, emulator, arch, > + machine, virttype, 0); > + > + if (!caps_xml) { > + vshError(ctl, "%s", _("failed to get hypervisor CPU model names")); > + return false; > + } > + > + return virshDumpXML(ctl, caps_xml, "domcapabilities", > + vshCommandOptBool(cmd, "all") ? xpath_all : xpath_usable, > + false); > +} > + > + Reviewed-by: Ján Tomko <jtomko(a)redhat.com&gt; Jano