[libvirt PATCH] nodedev: handle mdevs from multiple parents

[Jonathon Jongsma]

ping

On Thu, Jun 10, 2021 at 1:18 PM Jonathon Jongsma <jjongsma at redhat.com> wrote:
>
> Due to a rather unfortunate misunderstanding, we were parsing the list
> of defined devices from mdevctl incorrectly. Since my primary
> development machine only has a single device capable of mdevs, I
> apparently neglected to test multiple parent devices and made some
> assumptions based on reading the mdevctl code. These assumptions turned
> out to be incorrect, so the parsing failed when devices from more than
> one parent device were returned.
>
> The details: mdevctl returns an array of objects representing the
> defined devices. But instead of an array of multiple objects (with each
> object representing a parent device), the array always contains only a
> single object. That object has a separate property for each parent
> device.
>
> Signed-off-by: Jonathon Jongsma <jjongsma at redhat.com>
> ---
>  src/node_device/node_device_driver.c          | 41 ++++++++++---------
>  .../mdevctl-list-multiple.json                |  4 +-
>  2 files changed, 23 insertions(+), 22 deletions(-)
>
> diff --git a/src/node_device/node_device_driver.c b/src/node_device/node_device_driver.c
> index 8a0a2c3847..cb2c3ceaa4 100644
> --- a/src/node_device/node_device_driver.c
> +++ b/src/node_device/node_device_driver.c
> @@ -1056,6 +1056,7 @@ nodeDeviceParseMdevctlJSON(const char *jsonstring,
>      size_t noutdevs = 0;
>      size_t i;
>      size_t j;
> +    virJSONValue *obj;
>
>      json_devicelist = virJSONValueFromString(jsonstring);
>
> @@ -1065,31 +1066,33 @@ nodeDeviceParseMdevctlJSON(const char *jsonstring,
>          goto error;
>      }
>
> -    n = virJSONValueArraySize(json_devicelist);
> +    /* mdevctl list --dumpjson produces an output that is an array that
> +     * contains only a single object which contains a property for each parent
> +     * device */
> +    if (virJSONValueArraySize(json_devicelist) != 1) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                       _("Unexpected format for mdevctl response"));
> +        goto error;
> +    }
> +
> +    obj = virJSONValueArrayGet(json_devicelist, 0);
> +
> +    if (!virJSONValueIsObject(obj)) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                       _("device list is not an object"));
> +        goto error;
> +    }
>
> +    n = virJSONValueObjectKeysNumber(obj);
>      for (i = 0; i < n; i++) {
> -        virJSONValue *obj = virJSONValueArrayGet(json_devicelist, i);
>          const char *parent;
>          virJSONValue *child_array;
>          int nchildren;
>
> -        if (!virJSONValueIsObject(obj)) {
> -            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> -                           _("Parent device is not an object"));
> -            goto error;
> -        }
> -
> -        /* mdevctl returns an array of objects.  Each object is a parent device
> -         * object containing a single key-value pair which maps from the name
> -         * of the parent device to an array of child devices */
> -        if (virJSONValueObjectKeysNumber(obj) != 1) {
> -            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> -                           _("Unexpected format for parent device object"));
> -            goto error;
> -        }
> -
> -        parent = virJSONValueObjectGetKey(obj, 0);
> -        child_array = virJSONValueObjectGetValue(obj, 0);
> +        /* The key of each object property is the name of a parent device
> +         * which maps to an array of child devices */
> +        parent = virJSONValueObjectGetKey(obj, i);
> +        child_array = virJSONValueObjectGetValue(obj, i);
>
>          if (!virJSONValueIsArray(child_array)) {
>              virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> diff --git a/tests/nodedevmdevctldata/mdevctl-list-multiple.json b/tests/nodedevmdevctldata/mdevctl-list-multiple.json
> index eefcd90c62..ca1918d00a 100644
> --- a/tests/nodedevmdevctldata/mdevctl-list-multiple.json
> +++ b/tests/nodedevmdevctldata/mdevctl-list-multiple.json
> @@ -24,9 +24,7 @@
>            ]
>          }
>        }
> -    ]
> -  },
> -  {
> +    ],
>      "matrix": [
>        { "783e6dbb-ea0e-411f-94e2-717eaad438bf": {
>          "mdev_type": "vfio_ap-passthrough",
> --
> 2.31.1
>