[PATCH 2/3] conf: Add page_per_vq for driver element

[Jonathon Jongsma]

On Mon, Sep 6, 2021 at 9:07 AM Han Han <hhan at redhat.com> wrote:
>
> Signed-off-by: Han Han <hhan at redhat.com>
> ---
>  docs/formatdomain.rst         |  9 +++++++++
>  docs/schemas/domaincommon.rng |  5 +++++
>  src/conf/domain_conf.c        | 16 ++++++++++++++++
>  src/conf/domain_conf.h        |  1 +
>  src/conf/domain_validate.c    |  7 +++++++
>  5 files changed, 38 insertions(+)
>
> diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
> index 479a3acfbb..961676ac6b 100644
> --- a/docs/formatdomain.rst
> +++ b/docs/formatdomain.rst
> @@ -3546,6 +3546,15 @@ virtqueues are actually used depends on the feature negotiation between QEMU,
>  vhost backends and guest drivers. Possible values are ``on`` or ``off``.
>  :since:`Since 6.3.0 (QEMU and KVM only)`
>
> +This optional attribute ``page_per_vq`` controls the layout of the notification

Minor quibble: "This optional attribute" should be "The optional
attribute"

> +capabilities exposed to the guest. When enabled, each virtio queue will have a
> +dedicated page on the device BAR exposed to the guest. It is recommended to be
> +used when vDPA is enabled on the hypervisor, as it enables mapping the
> +notification area to the physical device, which is only supported in page
> +granularity. The default is determined by QEMU. :since:`Since 7.8.0`
> +Note: In general you should leave this option alone, unless you are very certain
> +you know what you are doing.
> +
>  :anchor:`<a id="elementsVirtioTransitional"/>`
>
>  Virtio transitional devices
> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
> index 11fa24f398..fb97364e15 100644
> --- a/docs/schemas/domaincommon.rng
> +++ b/docs/schemas/domaincommon.rng
> @@ -6789,6 +6789,11 @@
>          <ref name="virOnOff"/>
>        </attribute>
>      </optional>
> +    <optional>
> +      <attribute name="page_per_vq">
> +        <ref name="virOnOff"/>
> +      </attribute>
> +    </optional>
>    </define>
>
>    <define name="usbmaster">
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index 6127513117..1abfe29dd9 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -1629,6 +1629,10 @@ virDomainVirtioOptionsParseXML(xmlNodePtr driver,
>                                   &(*virtio)->packed) < 0)
>          return -1;
>
> +    if (virXMLPropTristateSwitch(driver, "page_per_vq", VIR_XML_PROP_NONE,
> +                                 &(*virtio)->page_per_vq) < 0)
> +        return -1;
> +
>      return 0;
>  }
>
> @@ -6311,6 +6315,10 @@ virDomainVirtioOptionsFormat(virBuffer *buf,
>          virBufferAsprintf(buf, " packed='%s'",
>                            virTristateSwitchTypeToString(virtio->packed));
>      }
> +    if (virtio->page_per_vq != VIR_TRISTATE_SWITCH_ABSENT) {
> +        virBufferAsprintf(buf, " page_per_vq='%s'",
> +                          virTristateSwitchTypeToString(virtio->page_per_vq));
> +    }
>  }
>
>
> @@ -20699,6 +20707,14 @@ virDomainVirtioOptionsCheckABIStability(virDomainVirtioOptions *src,
>                         virTristateSwitchTypeToString(src->packed));
>          return false;
>      }
> +    if (src->page_per_vq != dst->page_per_vq) {
> +        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                       _("Target device page_per_vq option '%s' does not "
> +                         "match source '%s'"),
> +                       virTristateSwitchTypeToString(dst->page_per_vq),
> +                       virTristateSwitchTypeToString(src->page_per_vq));
> +        return false;
> +    }
>      return true;
>  }
>
> diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
> index c7e6df7981..e21683a71f 100644
> --- a/src/conf/domain_conf.h
> +++ b/src/conf/domain_conf.h
> @@ -2725,6 +2725,7 @@ struct _virDomainVirtioOptions {
>      virTristateSwitch iommu;
>      virTristateSwitch ats;
>      virTristateSwitch packed;
> +    virTristateSwitch page_per_vq;
>  };
>
>
> diff --git a/src/conf/domain_validate.c b/src/conf/domain_validate.c
> index 60f7ccdddd..f22f952464 100644
> --- a/src/conf/domain_validate.c
> +++ b/src/conf/domain_validate.c
> @@ -134,6 +134,13 @@ virDomainCheckVirtioOptionsAreAbsent(virDomainVirtioOptions *virtio)
>                           "for virtio devices"));
>          return -1;
>      }
> +
> +    if (virtio->page_per_vq != VIR_TRISTATE_SWITCH_ABSENT) {
> +        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> +                       _("page_per_vq option is only supported "
> +                         "for virtio devices"));
> +        return -1;
> +    }
>      return 0;
>  }
>
> --
> 2.31.1
>