[libvirt] [PATCH v2 03/16] domain: add rendernode attribute on <accel>

[Cole Robinson]

On 8/23/19 12:21 PM, Cole Robinson wrote:
> From: Marc-André Lureau <marcandre.lureau at redhat.com>
> 
> vhost-user-gpu helper may accept --render-node option to specify on
> which GPU should the renderning be done.
> 

What does it do if the user doesn't pass one? Pick one itself, or just
not use one somehow?

If it picks one, then we may need to treat this like we treat other
rendernode instances and autoallocate one if the user doesn't specify,
otherwise we won't be able to add the path to the cgroup for example, or
selinux label it if necessary. I'm not sure if that actually applies in
this case, but it's worth considering.

> (by comparison <graphics> rendernode is the target/display rendering)
> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau at redhat.com>
> Signed-off-by: Cole Robinson <crobinso at redhat.com>

Also I see now that I accidentally signed off all these patches, that
was not intentional. Please strip those from v3

> ---
>  docs/formatdomain.html.in     |  5 +++++
>  docs/schemas/domaincommon.rng |  5 +++++
>  src/conf/domain_conf.c        | 18 +++++++++++++++++-
>  src/conf/domain_conf.h        |  1 +
>  4 files changed, 28 insertions(+), 1 deletion(-)
> 
> diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
> index ec650fbe17..5a4807d937 100644
> --- a/docs/formatdomain.html.in
> +++ b/docs/formatdomain.html.in
> @@ -7059,6 +7059,11 @@ qemu-kvm -net nic,model=? /dev/null
>          <dd>Enable 3D acceleration (for vbox driver
>          <span class="since">since 0.7.1</span>, qemu driver
>          <span class="since">since 1.3.0</span>)</dd>
> +
> +        <dt><code>rendernode</code></dt>
> +        <dd>Absolute path to a host's DRI device to be used for
> +        rendering (for vhost-user driver only, <span
> +        class="since">since 5.5.0</span>)</dd>
>          </dl>
>        </dd>
>  
> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
> index bac566855d..6e91fe6cef 100644
> --- a/docs/schemas/domaincommon.rng
> +++ b/docs/schemas/domaincommon.rng
> @@ -3644,6 +3644,11 @@
>                    <ref name="virYesNo"/>
>                  </attribute>
>                </optional>
> +              <optional>
> +                <attribute name="rendernode">
> +                  <ref name="absFilePath"/>
> +                </attribute>
> +              </optional>
>              </element>
>            </optional>
>          </element>
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index f51575d57d..2cc055491d 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -2832,6 +2832,8 @@ virDomainVideoDefClear(virDomainVideoDefPtr def)
>  
>      virDomainDeviceInfoClear(&def->info);
>  
> +    if (def->accel)
> +        VIR_FREE(def->accel->rendernode);
>      VIR_FREE(def->accel);
>      VIR_FREE(def->virtio);
>      VIR_FREE(def->driver);
> @@ -15270,6 +15272,7 @@ virDomainVideoAccelDefParseXML(xmlNodePtr node)
>      int val;
>      VIR_AUTOFREE(char *) accel2d = NULL;
>      VIR_AUTOFREE(char *) accel3d = NULL;
> +    VIR_AUTOFREE(char *) rendernode = NULL;
>  
>      cur = node->children;
>      while (cur != NULL) {
> @@ -15278,12 +15281,13 @@ virDomainVideoAccelDefParseXML(xmlNodePtr node)
>                  virXMLNodeNameEqual(cur, "acceleration")) {
>                  accel3d = virXMLPropString(cur, "accel3d");
>                  accel2d = virXMLPropString(cur, "accel2d");
> +                rendernode = virXMLPropString(cur, "rendernode");
>              }
>          }
>          cur = cur->next;
>      }
>  
> -    if (!accel3d && !accel2d)
> +    if (!accel3d && !accel2d && !rendernode)
>          return NULL;
>  
>      if (VIR_ALLOC(def) < 0)
> @@ -15307,6 +15311,9 @@ virDomainVideoAccelDefParseXML(xmlNodePtr node)
>          def->accel2d = val;
>      }
>  
> +    if (VIR_STRDUP(def->rendernode, rendernode) < 0)
> +        goto cleanup;
> +

Huh, this function has no error reporting? A bogus accel2d/accel3d value
will raise an error but it never triggers the error path in the calling
function. Not your fault of course :)

>   cleanup:
>      return def;
>  }
> @@ -15474,6 +15481,11 @@ virDomainVideoDefParseXML(virDomainXMLOptionPtr xmlopt,
>              goto error;
>          }
>      }
> +    if (!def->vhostuser && def->accel && def->accel->rendernode) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                       _("unsupported rendernode accel attribute without 'vhost-user'"));
> +        goto error;
> +    }
>  

This function doesn't represent best practices, but this style of check
should be moved to virDomainVideoDefValidate IMO

Thanks,
Cole