[libvirt PATCH v3 4/6] conf: add support for 'blob' in virtio video device

[Han Han]

On Wed, May 11, 2022 at 12:26 AM Jonathon Jongsma <jjongsma at redhat.com>
wrote:

> Add the ability to enable blob resources for the virtio video device.
> This will accelerate the display path due to less or no copying of pixel
> data.
>
> Blob resource support can be enabled with e.g.:
>
>     <video>
>       <model type='virtio' blob='on'/>
>     </video>
>
> Some additional background information about blob resources:
> https://lists.freedesktop.org/archives/dri-devel/2020-August/275972.html
> https://www.kraxel.org/blog/2021/05/virtio-gpu-qemu-graphics-update/
>
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2032406
>
> Signed-off-by: Jonathon Jongsma <jjongsma at redhat.com>
> ---
>  docs/formatdomain.rst             |  6 ++++++
>  src/conf/domain_conf.c            |  6 ++++++
>  src/conf/domain_conf.h            |  1 +
>  src/conf/domain_validate.c        | 13 ++++++++++---
>  src/conf/schemas/domaincommon.rng |  5 +++++
>  5 files changed, 28 insertions(+), 3 deletions(-)
>
> diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
> index 993c65e50b..2161cc7e30 100644
> --- a/docs/formatdomain.rst
> +++ b/docs/formatdomain.rst
> @@ -6198,6 +6198,12 @@ A video device.
>     :since:`since 1.3.3` ) extends secondary bar and makes it addressable
> as
>     64bit memory.
>
> +   :since:`Since 8.2.0`, devices with type "virtio" have an optional
> ``blob``
>
Since 8.4.0 for libvirt.
And please mention the QEMU version 6.1.0

> +   attribute that can be set to "on" or "off". Setting ``blob`` to "on"
> will
> +   enable the use of blob resources in the device. This can accelerate the
> +   display path by reducing or eliminating copying of pixel data between
> the
> +   guest and host.
> +
>     :since:`Since 5.9.0` , the ``model`` element may also have an optional
>     ``resolution`` sub-element. The ``resolution`` element has attributes
> ``x``
>     and ``y`` to set the minimum resolution for the video device. This
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index 60c27ddd34..ae86f455bd 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -14154,6 +14154,9 @@ virDomainVideoModelDefParseXML(virDomainVideoDef
> *def,
>      else if (rc == 0)
>          def->heads = 1;
>
> +    if (virXMLPropTristateSwitch(node, "blob", VIR_XML_PROP_NONE,
> &def->blob) < 0)
> +        return -1;
> +
>      return 0;
>  }
>
> @@ -26075,6 +26078,9 @@ virDomainVideoDefFormat(virBuffer *buf,
>          virBufferAsprintf(buf, " heads='%u'", def->heads);
>      if (def->primary)
>          virBufferAddLit(buf, " primary='yes'");
> +    if (def->blob != VIR_TRISTATE_SWITCH_ABSENT)
> +        virBufferAsprintf(buf, " blob='%s'",
> +                          virTristateSwitchTypeToString(def->blob));
>      if (def->accel || def->res) {
>          virBufferAddLit(buf, ">\n");
>          virBufferAdjustIndent(buf, 2);
> diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
> index acd0588e9b..afa6db2403 100644
> --- a/src/conf/domain_conf.h
> +++ b/src/conf/domain_conf.h
> @@ -1763,6 +1763,7 @@ struct _virDomainVideoDef {
>      bool primary;
>      virDomainVideoAccelDef *accel;
>      virDomainVideoResolutionDef *res;
> +    virTristateSwitch blob;
>      virDomainVideoDriverDef *driver;
>      virDomainDeviceInfo info;
>      virDomainVirtioOptions *virtio;
> diff --git a/src/conf/domain_validate.c b/src/conf/domain_validate.c
> index 18eb8d697d..da0ff06570 100644
> --- a/src/conf/domain_validate.c
> +++ b/src/conf/domain_validate.c
> @@ -226,9 +226,16 @@ virDomainVideoDefValidate(const virDomainVideoDef
> *video,
>          }
>      }
>
> -    if (video->type != VIR_DOMAIN_VIDEO_TYPE_VIRTIO &&
> -        (virDomainCheckVirtioOptionsAreAbsent(video->virtio) < 0))
> -        return -1;
> +    if (video->type != VIR_DOMAIN_VIDEO_TYPE_VIRTIO) {
> +        if (virDomainCheckVirtioOptionsAreAbsent(video->virtio) < 0)
> +            return -1;
> +        if (video->blob != VIR_TRISTATE_SWITCH_ABSENT) {
> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                           _("video type '%s' does not support blob
> resources"),
> +                           virDomainVideoTypeToString(video->type));
> +            return -1;
> +        }
> +    }
>
>      return 0;
>  }
> diff --git a/src/conf/schemas/domaincommon.rng
> b/src/conf/schemas/domaincommon.rng
> index 2544864eb4..16b3fd9c53 100644
> --- a/src/conf/schemas/domaincommon.rng
> +++ b/src/conf/schemas/domaincommon.rng
> @@ -4251,6 +4251,11 @@
>                  <ref name="virYesNo"/>
>                </attribute>
>              </optional>
> +            <optional>
> +              <attribute name="blob">
> +                <ref name="virOnOff"/>
> +              </attribute>
> +            </optional>
>              <optional>
>                <element name="acceleration">
>                  <optional>
> --
> 2.35.1
>
>
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