diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
index 67d5f958d5..0a4f9d9000 100644
--- a/docs/formatdomain.rst
+++ b/docs/formatdomain.rst
@@ -8443,6 +8443,19 @@ Example: usage of the memory devices
The ``node`` subelement configures the guest NUMA node to attach the memory
to. The element shall be used only if the guest has NUMA nodes configured.
+ For ``virtio-mem`` optional attribute ``dynamicMemslots`` can be specified
+ (accepted values "yes"/"no") which allows hypervisor to spread memory into
+ multiple memory slots (allocate them dynamically based on the amount of
+ memory exposed to the guest), resulting in smaller memory footprint. But be
+ aware this may affect vhost-user devices. When enabled, older vhost-user
+ device implementations (such as virtiofs) may refuse to initialize resulting
+ in failed domain startup or device hotplug. When only modern vhost-user
+ based devices will be used or when no vhost-user devices are expected to be
+ used it's beneficial to enable this feature. The current default is
+ hypervisor dependant (for QEMU is "no"). If the default changes and you are
+ having difficulties with vhost-user devices, try toggling this to "no".
+ :since:`Since 10.1.0 and QEMU 8.2.0`
+
The following optional elements may be used:
``label``
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 59d51c4c52..fb5a5cc351 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -13558,6 +13558,10 @@ virDomainMemoryTargetDefParseXML(xmlNodePtr node,
&def->target.virtio_mem.requestedsize, false, false) < 0)
return -1;
+ if (virXMLPropTristateBool(node, "dynamicMemslots", VIR_XML_PROP_NONE,
+ &def->target.virtio_mem.dynamicMemslots) < 0)
+ return -1;
+
addrNode = virXPathNode("./address", ctxt);
addr = &def->target.virtio_mem.address;
break;
@@ -21232,6 +21236,12 @@ virDomainMemoryDefCheckABIStability(virDomainMemoryDef *src,
src->target.virtio_mem.address);
return false;
}
+
+ if (src->target.virtio_mem.dynamicMemslots != dst->target.virtio_mem.dynamicMemslots) {
+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+ _("Target memory device 'dynamicMemslots' property doesn't match source memory device"));
+ return false;
+ }
break;
case VIR_DOMAIN_MEMORY_MODEL_DIMM:
@@ -25448,6 +25458,7 @@ virDomainMemoryTargetDefFormat(virBuffer *buf,
unsigned int flags)
{
g_auto(virBuffer) childBuf = VIR_BUFFER_INIT_CHILD(buf);
+ g_auto(virBuffer) attrBuf = VIR_BUFFER_INITIALIZER;
virBufferAsprintf(&childBuf, "%llu\n", def->size);
if (def->targetNode >= 0)
@@ -25487,6 +25498,11 @@ virDomainMemoryTargetDefFormat(virBuffer *buf,
if (def->target.virtio_mem.address)
virBufferAsprintf(&childBuf, "\n",
def->target.virtio_mem.address);
+
+ if (def->target.virtio_mem.dynamicMemslots) {
+ virBufferAsprintf(&attrBuf, " dynamicMemslots='%s'",
+ virTristateBoolTypeToString(def->target.virtio_mem.dynamicMemslots));
+ }
break;
case VIR_DOMAIN_MEMORY_MODEL_SGX_EPC:
@@ -25496,7 +25512,7 @@ virDomainMemoryTargetDefFormat(virBuffer *buf,
break;
}
- virXMLFormatElement(buf, "target", NULL, &childBuf);
+ virXMLFormatElement(buf, "target", &attrBuf, &childBuf);
}
static int
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index d176bda5f8..bd283d42df 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -2676,6 +2676,7 @@ struct _virDomainMemoryDef {
unsigned long long currentsize; /* kibibytes, valid for an active
domain only and parsed */
unsigned long long address; /* address where memory is mapped */
+ virTristateBool dynamicMemslots;
} virtio_mem;
struct {
} sgx_epc;
diff --git a/src/conf/schemas/domaincommon.rng b/src/conf/schemas/domaincommon.rng
index a34427c330..df44cd9857 100644
--- a/src/conf/schemas/domaincommon.rng
+++ b/src/conf/schemas/domaincommon.rng
@@ -7268,6 +7268,11 @@
+
+
+