From a73dc19ce9a528f18c02f39e62c831ad7d60955c Mon Sep 17 00:00:00 2001
From: James Shubin <james@shubin.ca>
Date: Sat, 13 Sep 2025 23:33:51 -0400
Subject: [PATCH] engine: resources: Fix virt hotplug

At some point, this seems to have rotted, since I assume upstream
started requiring this updated XML spec. Fix it now.
---
 engine/resources/virt.go        | 3 ++-
 modules/virtualization/main.mcl | 8 ++++----
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/engine/resources/virt.go b/engine/resources/virt.go
index 4f1ad7c7..c7cf34e5 100644
--- a/engine/resources/virt.go
+++ b/engine/resources/virt.go
@@ -939,7 +939,8 @@ func (obj *VirtRes) getDomainXML() string {
 			if i < obj.CPUs {
 				enabled = "yes"
 			}
-			b += fmt.Sprintf("<vcpu id='%d' enabled='%s' hotpluggable='yes'/>", i, enabled)
+			// all vcpus must have either set or unset order
+			b += fmt.Sprintf("<vcpu id='%d' enabled='%s' hotpluggable='yes' order='%d'/>", i, enabled, i+1)
 		}
 		b += fmt.Sprintf("</vcpus>")
 	} else {
diff --git a/modules/virtualization/main.mcl b/modules/virtualization/main.mcl
index 64254aa6..a1759cfd 100644
--- a/modules/virtualization/main.mcl
+++ b/modules/virtualization/main.mcl
@@ -138,11 +138,11 @@ class vm($name, $config) {
 	$mac_6 = strings.substr($hex, 2, 3) + strings.substr($hex, 3, 4) # TODO: support $hex[2] or $hex[2:2] ?
 	$mac_tail = "01:" + $mac_5 + ":" + $mac_6
 
-	# XXX: with hotcpus => true AND cpus => 2 I get:
-	# domainCreate failed: virError(Code=67, Domain=10, Message='unsupported configuration: all vcpus must have either set or unset order')
+	$cpus = $config->cpus || 2
+
 	virt "${name}" {
 		uri => "qemu:///session",
-		cpus => 2,
+		cpus => $cpus,
 		maxcpus => 8,
 		memory => 1024*1024*16, # 16G of RAM
 		state => "running",
@@ -170,7 +170,7 @@ class vm($name, $config) {
 			username => "",
 			password => "",
 		},
-		hotcpus => false, # no fun today!
+		hotcpus => true, # "that's hot!"
 		restartondiverge => "",
 		restartonrefresh => false,