[libvirt] [PATCH v1 4/4] qemu: monitor: implement query-cpu-model-comparison

Daniel Henrique Barboza danielhb413 at gmail.com
Wed Apr 17 20:19:06 UTC 2019



On 4/15/19 5:59 PM, Collin Walling wrote:
> Interfaces with QEMU to compare CPU models. The command takes two
> CPU models, A and B, that are given a model name and an optional list
> of CPU features. Through the query-cpu-model-comparison command issued
> via QMP, a result is produced that contains the comparison evaluation
> string (identical, superset, subset [s390x specific], incompatible)
> as well as a list of properties (aka CPU features) responsible for
> the subset or superset result.
>
> Though the "responsible properties" are captured, they are not
> reported by libvirt.
>
> This command is hooked into the virsh hypervisor-cpu-compare command.
> As such, the CPU model XML provided to the command will be compared
> to the hypervisor CPU contained in the QEMU capabilities file for the
> appropriate QEMU binary (for s390x, this CPU definition can be observed
> via virsh domcapabilities).
>
> s390x can report that the first model (A) is a subset of the second
> (B). If A is the hypervisor CPU and a subset of B (the CPU contained
> in the XML), then B would not be able to run on this machine and thus
> we will report that CPU model B is incompatible.
>
> Signed-off-by: Collin Walling <walling at linux.ibm.com>
> ---
>   src/qemu/qemu_capabilities.c | 47 +++++++++++++++++++
>   src/qemu/qemu_capabilities.h |  9 ++++
>   src/qemu/qemu_driver.c       | 10 ++++
>   src/qemu/qemu_monitor.c      | 22 +++++++++
>   src/qemu/qemu_monitor.h      | 10 ++++
>   src/qemu/qemu_monitor_json.c | 89 ++++++++++++++++++++++++++++++++++++
>   src/qemu/qemu_monitor_json.h | 11 +++++
>   7 files changed, 198 insertions(+)
>
> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
> index 6163fd5399..1e4b05d535 100644
> --- a/src/qemu/qemu_capabilities.c
> +++ b/src/qemu/qemu_capabilities.c
> @@ -5400,3 +5400,50 @@ virQEMUCapsStripMachineAliases(virQEMUCapsPtr qemuCaps)
>       for (i = 0; i < qemuCaps->nmachineTypes; i++)
>           VIR_FREE(qemuCaps->machineTypes[i].alias);
>   }
> +
> +virCPUCompareResult
> +virQEMUCapsCPUModelComparison(virQEMUCapsPtr qemuCaps,
> +                              const char *libDir,
> +                              uid_t runUid,
> +                              gid_t runGid,
> +                              virCPUDefPtr cpu_a,
> +                              virCPUDefPtr cpu_b,
> +                              bool failIncompatible)
> +{
> +    qemuProcessQMPPtr proc = NULL;
> +    qemuMonitorCPUModelInfoPtr result;
> +    int ret = -1;
> +
> +    if (!(proc = qemuProcessQMPNew(qemuCaps->binary, libDir,
> +                                   runUid, runGid, false)))
> +        goto cleanup;
> +
> +    if (qemuProcessQMPStart(proc) < 0)
> +        goto cleanup;
> +
> +    if (qemuMonitorGetCPUModelComparison(proc->mon, cpu_a->model,
> +                                         cpu_a->nfeatures, cpu_a->features,
> +                                         cpu_b->model, cpu_b->nfeatures,
> +                                         cpu_b->features, &result) < 0)
> +        goto cleanup;
> +
> +    if (STREQ(result->name, "incompatible") ||
> +        STREQ(result->name, "subset"))
> +        ret = VIR_CPU_COMPARE_INCOMPATIBLE;
> +    else if (STREQ(result->name, "identical"))
> +        ret = VIR_CPU_COMPARE_IDENTICAL;
> +    else if (STREQ(result->name, "superset"))
> +        ret = VIR_CPU_COMPARE_SUPERSET;
> +
> +    if (failIncompatible && ret == VIR_CPU_COMPARE_INCOMPATIBLE) {
> +        ret = VIR_CPU_COMPARE_ERROR;
> +        virReportError(VIR_ERR_CPU_INCOMPATIBLE, NULL);
> +    }
> +
> + cleanup:
> +    if (ret < 0)
> +        virQEMUCapsLogProbeFailure(qemuCaps->binary);
> +
> +    qemuProcessQMPFree(proc);

Don't you need to free 'result' here as well? This pointer is being passed
down to 'qemuMonitorJSONGetCPUModelComparison', receiving the
value of 'compare', which is VIR_ALLOC'd inside that function.




> +    return ret;
> +}
> diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h
> index 0cc3d4d512..aa27b18d32 100644
> --- a/src/qemu/qemu_capabilities.h
> +++ b/src/qemu/qemu_capabilities.h
> @@ -647,4 +647,13 @@ virQEMUCapsGetSEVCapabilities(virQEMUCapsPtr qemuCaps);
>   virArch virQEMUCapsArchFromString(const char *arch);
>   const char *virQEMUCapsArchToString(virArch arch);
>   
> +virCPUCompareResult
> +virQEMUCapsCPUModelComparison(virQEMUCapsPtr qemuCaps,
> +                              const char *libDir,
> +                              uid_t runUid,
> +                              gid_t runGid,
> +                              virCPUDefPtr cpu_a,
> +                              virCPUDefPtr cpu_b,
> +                              bool failIncompatible);
> +
>   #endif /* LIBVIRT_QEMU_CAPABILITIES_H */
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 4510b0ce60..2084da1b9d 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -13463,9 +13463,11 @@ qemuConnectCompareHypervisorCPU(virConnectPtr conn,
>   {
>       int ret = VIR_CPU_COMPARE_ERROR;
>       virQEMUDriverPtr driver = conn->privateData;
> +    virQEMUDriverConfigPtr config = driver->config;
>       virQEMUCapsPtr qemuCaps = NULL;
>       bool failIncompatible;
>       virCPUDefPtr hvCPU;
> +    virCPUDefPtr cpu;
>       virArch arch;
>       virDomainVirtType virttype;
>   
> @@ -13500,6 +13502,14 @@ qemuConnectCompareHypervisorCPU(virConnectPtr conn,
>   
>       if (ARCH_IS_X86(arch)) {
>           ret = virCPUCompareXML(arch, hvCPU, xmlCPU, failIncompatible);
> +    } else if (ARCH_IS_S390(arch) &&
> +               virQEMUCapsGet(qemuCaps, QEMU_CAPS_QUERY_CPU_MODEL_COMPARISON)) {
> +        if (virCPUDefParseXMLHelper(xmlCPU, NULL, VIR_CPU_TYPE_AUTO, &cpu) < 0)
> +            goto cleanup;
> +
> +        ret = virQEMUCapsCPUModelComparison(qemuCaps, config->libDir,
> +                                            config->user, config->group,
> +                                            hvCPU, cpu, failIncompatible);
>       } else {
>           virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
>                          _("comparing with the hypervisor CPU is not supported "
> diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
> index babcbde878..5fd132a268 100644
> --- a/src/qemu/qemu_monitor.c
> +++ b/src/qemu/qemu_monitor.c
> @@ -3684,6 +3684,28 @@ qemuMonitorGetCPUModelExpansion(qemuMonitorPtr mon,
>   }
>   
>   
> +int
> +qemuMonitorGetCPUModelComparison(qemuMonitorPtr mon,
> +                                 const char *model_a_name,
> +                                 int model_a_nprops,
> +                                 virCPUFeatureDefPtr model_a_props,
> +                                 const char *model_b_name,
> +                                 int model_b_nprops,
> +                                 virCPUFeatureDefPtr model_b_props,
> +                                 qemuMonitorCPUModelInfoPtr *model_result)
> +{
> +    VIR_DEBUG("model_a_name=%s model_a_nprops=%d model_b_name=%s model_b_nprops=%d",
> +               model_a_name, model_a_nprops, model_b_name, model_b_nprops);
> +
> +    QEMU_CHECK_MONITOR(mon);
> +
> +    return qemuMonitorJSONGetCPUModelComparison(mon, model_a_name, model_a_nprops,
> +                                                model_a_props, model_b_name,
> +                                                model_b_nprops, model_b_props,
> +                                                model_result);
> +}
> +
> +
>   void
>   qemuMonitorCPUModelInfoFree(qemuMonitorCPUModelInfoPtr model_info)
>   {
> diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h
> index caf62af5e2..0a3ee493b1 100644
> --- a/src/qemu/qemu_monitor.h
> +++ b/src/qemu/qemu_monitor.h
> @@ -1066,6 +1066,16 @@ int qemuMonitorGetCPUModelExpansion(qemuMonitorPtr mon,
>   
>   void qemuMonitorCPUModelInfoFree(qemuMonitorCPUModelInfoPtr model_info);
>   
> +int
> +qemuMonitorGetCPUModelComparison(qemuMonitorPtr mon,
> +                                 const char *model_a_name,
> +                                 int model_a_nprops,
> +                                 virCPUFeatureDefPtr model_a_props,
> +                                 const char *model_b_name,
> +                                 int model_b_nprops,
> +                                 virCPUFeatureDefPtr model_b_props,
> +                                 qemuMonitorCPUModelInfoPtr *model_result);
> +
>   qemuMonitorCPUModelInfoPtr
>   qemuMonitorCPUModelInfoCopy(const qemuMonitorCPUModelInfo *orig);
>   
> diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
> index 992cec9efb..97cb7191e1 100644
> --- a/src/qemu/qemu_monitor_json.c
> +++ b/src/qemu/qemu_monitor_json.c
> @@ -5704,6 +5704,95 @@ qemuMonitorJSONGetCPUModelExpansion(qemuMonitorPtr mon,
>   }
>   
>   
> +static int
> +qemuMonitorJSONParseCPUModelPropName(size_t pos ATTRIBUTE_UNUSED,
> +                                     virJSONValuePtr item,
> +                                     void *opaque)
> +{
> +    return qemuMonitorJSONParseCPUModelProperty(virJSONValueGetString(item),
> +                                                item, opaque);
> +}
> +
> +
> +int
> +qemuMonitorJSONGetCPUModelComparison(qemuMonitorPtr mon,
> +                                     const char *model_a_name,
> +                                     int model_a_nprops,
> +                                     virCPUFeatureDefPtr model_a_props,
> +                                     const char *model_b_name,
> +                                     int model_b_nprops,
> +                                     virCPUFeatureDefPtr model_b_props,
> +                                     qemuMonitorCPUModelInfoPtr *model_result)
> +{
> +    int ret = -1;
> +    virJSONValuePtr model_a;
> +    virJSONValuePtr model_b = NULL;
> +    virJSONValuePtr cmd = NULL;
> +    virJSONValuePtr reply = NULL;
> +    virJSONValuePtr data;
> +    const char *result_name;
> +    virJSONValuePtr props;
> +    qemuMonitorCPUModelInfoPtr compare = NULL;
> +
> +    if (!(model_a = qemuMonitorJSONMakeCPUModel(model_a_name, model_a_nprops, model_a_props, true)) ||
> +        !(model_b = qemuMonitorJSONMakeCPUModel(model_b_name, model_b_nprops, model_b_props, true)))
> +        goto cleanup;
> +
> +    if (!(cmd = qemuMonitorJSONMakeCommand("query-cpu-model-comparison",
> +                                           "a:modela", &model_a,
> +                                           "a:modelb", &model_b,
> +                                           NULL)))
> +        goto cleanup;
> +
> +    if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0)
> +        goto cleanup;
> +
> +    if (qemuMonitorJSONCheckError(cmd, reply) < 0)
> +        goto cleanup;
> +
> +    data = virJSONValueObjectGetObject(reply, "return");
> +
> +    if (!(result_name = virJSONValueObjectGetString(data, "result"))) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                       _("query-cpu-model-comparison reply data was missing "
> +                         "'result'"));
> +        goto cleanup;
> +    }
> +
> +    if (!(props = virJSONValueObjectGetArray(data, "responsible-properties"))) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                       _("query-cpu-model-comparison reply data was missing "
> +                         "'responsible-properties'"));
> +        goto cleanup;
> +    }
> +
> +    if (VIR_ALLOC(compare) < 0)
> +        goto cleanup;
> +
> +    if (VIR_STRDUP(compare->name, result_name) < 0)
> +        goto cleanup;
> +
> +    if (VIR_ALLOC_N(compare->props, virJSONValueArraySize(props)) < 0)
> +        goto cleanup;
> +
> +    if (virJSONValueArrayForeachSteal(props,
> +                                      qemuMonitorJSONParseCPUModelPropName,
> +                                      compare) < 0)
> +        goto cleanup;
> +
> +    VIR_STEAL_PTR(*model_result, compare);
> +    ret = 0;
> +
> + cleanup:
> +    qemuMonitorCPUModelInfoFree(compare);
> +    virJSONValueFree(cmd);
> +    virJSONValueFree(reply);
> +    virJSONValueFree(model_a);
> +    virJSONValueFree(model_b);
> +    return ret;
> +}
> +
> +
>   int qemuMonitorJSONGetCommands(qemuMonitorPtr mon,
>                                  char ***commands)
>   {
> diff --git a/src/qemu/qemu_monitor_json.h b/src/qemu/qemu_monitor_json.h
> index c10513da15..e69be46dd5 100644
> --- a/src/qemu/qemu_monitor_json.h
> +++ b/src/qemu/qemu_monitor_json.h
> @@ -367,6 +367,17 @@ int qemuMonitorJSONGetCPUModelExpansion(qemuMonitorPtr mon,
>                                           qemuMonitorCPUModelInfoPtr *model_info)
>       ATTRIBUTE_NONNULL(3) ATTRIBUTE_NONNULL(5);
>   
> +int
> +qemuMonitorJSONGetCPUModelComparison(qemuMonitorPtr mon,
> +                                     const char *model_a_name,
> +                                     int model_a_nprops,
> +                                     virCPUFeatureDefPtr model_a_props,
> +                                     const char *model_b_name,
> +                                     int model_b_nprops,
> +                                     virCPUFeatureDefPtr model_b_props,
> +                                     qemuMonitorCPUModelInfoPtr *model_result)
> +    ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(5) ATTRIBUTE_NONNULL(8);
> +
>   int qemuMonitorJSONGetCommands(qemuMonitorPtr mon,
>                                  char ***commands)
>       ATTRIBUTE_NONNULL(2);




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