[PATCH v2 2/3] conf: Add page_per_vq for driver element

[Han Han]

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    |  6 ++++++
 5 files changed, 37 insertions(+)

diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
index a02802a954..289e7bf5f1 100644
--- a/docs/formatdomain.rst
+++ b/docs/formatdomain.rst
@@ -3548,6 +3548,15 @@ 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
+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 ec5bd91740..f71e375a33 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -6810,6 +6810,11 @@
         <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 b8370f6950..04bdd110b6 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -1630,6 +1630,10 @@ 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;
 }
 
@@ -6314,6 +6318,10 @@ 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));
+    }
 }
 
 
@@ -20784,6 +20792,14 @@ 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 c23c233184..d6bc3dd0d2 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -2733,6 +2733,7 @@ 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 f023d22f23..80401cf8c7 100644
--- a/src/conf/domain_validate.c
+++ b/src/conf/domain_validate.c
@@ -135,6 +135,12 @@ 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