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

[Jonathon Jongsma]

On 5/11/22 9:56 AM, Han Han wrote:
> 
> 
> On Wed, May 11, 2022 at 12:26 AM Jonathon Jongsma <jjongsma at redhat.com 
> <mailto: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://lists.freedesktop.org/archives/dri-devel/2020-August/275972.html>
>     https://www.kraxel.org/blog/2021/05/virtio-gpu-qemu-graphics-update/
>     <https://www.kraxel.org/blog/2021/05/virtio-gpu-qemu-graphics-update/>
> 
>     Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2032406
>     <https://bugzilla.redhat.com/show_bug.cgi?id=2032406>
> 
>     Signed-off-by: Jonathon Jongsma <jjongsma at redhat.com
>     <mailto: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.

Oops. Didn't catch that in the rebase.

> And please mention the QEMU version 6.1.0

There are a lot of libvirt features that require minimum versions of 
qemu, but it doesn't look like we generally specify these qemu version 
requirements in the libvirt documentation. Not sure if I should add it 
here...

> 
>     +   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
>