[libvirt] [PATCH 2/2] qemu: Check for presence of device and properities when getting CPUID

[Guido Günther]

On Tue, Nov 12, 2013 at 10:04:33AM +0100, Peter Krempa wrote:
> The QOM path in qemu that contains the CPUID registers of a running VM
> may not be present (introduced in QEMU 1.5).
> 
> Since commit d94b7817719 we have a regression with QEMU that don't
> support reporting of the CPUID register state via the monitor as the
> process startup code expects the path to exist.
> 
> This patch adds code that checks with the monitor if the requested path
> already exists and uses it only in this case.
> ---
>  src/qemu/qemu_monitor_json.c | 50 ++++++++++++++++++++++++++++++++++++++++++--
>  tests/qemumonitorjsontest.c  | 16 ++++++++++++++
>  2 files changed, 64 insertions(+), 2 deletions(-)
> 
> diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
> index 87990e2..e716fb3 100644
> --- a/src/qemu/qemu_monitor_json.c
> +++ b/src/qemu/qemu_monitor_json.c
> @@ -5508,20 +5508,66 @@ qemuMonitorJSONGetCPUx86Data(qemuMonitorPtr mon,
>                               const char *property,
>                               virCPUDataPtr *cpudata)
>  {
> -    virJSONValuePtr cmd;
> +    virJSONValuePtr cmd = NULL;
>      virJSONValuePtr reply = NULL;
>      virJSONValuePtr data;
> +    virJSONValuePtr element;
>      virCPUx86Data *x86Data = NULL;
>      virCPUx86CPUID cpuid;
>      size_t i;
>      int n;
>      int ret = -1;
> 
> +    /* look up if the property exists before asking */
> +    if (!(cmd = qemuMonitorJSONMakeCommand("qom-list",
> +                                           "s:path", QOM_CPU_PATH,
> +                                           NULL)))
> +        goto cleanup;
> +
> +    if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0)
> +        goto cleanup;
> +
> +    /* check if device exists */
> +    if ((data = virJSONValueObjectGet(reply, "error")) &&
> +        STREQ_NULLABLE(virJSONValueObjectGetString(data, "class"),
> +                       "DeviceNotFound")) {
> +        ret = -2;
> +        goto cleanup;
> +    }
> +
> +    if (qemuMonitorJSONCheckError(cmd, reply))
> +        goto cleanup;
> +
> +    data = virJSONValueObjectGet(reply, "return");
> +
> +    if ((n = virJSONValueArraySize(data)) < 0) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR,
> +                       _("%s CPU property did not return an array"),
> +                       property);
> +        goto cleanup;
> +    }
> +
> +    for (i = 0; i < n; i++) {
> +        element = virJSONValueArrayGet(data, i);
> +        if (STREQ_NULLABLE(virJSONValueObjectGetString(element, "name"),
> +                           property))
> +            break;
> +    }
> +
> +    /* "property" was not found */
> +    if (i == n) {
> +        ret = -2;
> +        goto cleanup;
> +    }
> +
> +    virJSONValueFree(cmd);
> +    virJSONValueFree(reply);
> +
>      if (!(cmd = qemuMonitorJSONMakeCommand("qom-get",
>                                             "s:path", QOM_CPU_PATH,
>                                             "s:property", property,
>                                             NULL)))
> -        return -1;
> +        goto cleanup;
> 
>      if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0)
>          goto cleanup;
> diff --git a/tests/qemumonitorjsontest.c b/tests/qemumonitorjsontest.c
> index 5636d95..4cdb938 100644
> --- a/tests/qemumonitorjsontest.c
> +++ b/tests/qemumonitorjsontest.c
> @@ -1994,6 +1994,22 @@ testQemuMonitorJSONGetCPUData(const void *opaque)
>          virtTestLoadFile(dataFile, &expected) < 0)
>          goto cleanup;
> 
> +    if (qemuMonitorTestAddItem(test, "qom-list",
> +                               "{"
> +                               "    \"return\": ["
> +                               "        {"
> +                               "            \"name\": \"filtered-features\","
> +                               "            \"type\": \"X86CPUFeatureWordInfo\""
> +                               "        },"
> +                               "        {"
> +                               "            \"name\": \"feature-words\","
> +                               "            \"type\": \"X86CPUFeatureWordInfo\""
> +                               "        }"
> +                               "    ],"
> +                               "    \"id\": \"libvirt-19\""
> +                               "}") < 0)
> +        goto cleanup;
> +
>      if (qemuMonitorTestAddItem(test, "qom-get", jsonStr) < 0)
>          goto cleanup;

ACK.
 -- Guido

> 
> -- 
> 1.8.4.2
> 
> --
> libvir-list mailing list
> libvir-list at redhat.com
> https://www.redhat.com/mailman/listinfo/libvir-list
>