incusd/instance/qemu: rtc base localtime for windows

Closes #1752

Signed-off-by: JUN JIE NAN <[email protected]>

Author: nanjj

internal/server/instance/drivers/driver_qemu.go

@@ -1500,6 +1500,11 @@ func (d *qemu) start(stateful bool, op *operationlock.InstanceOperation) error {
 		}
 	}
 
+	rtcBase := "base=utc"
+	if d.windowsOS() {
+		rtcBase = "base=localtime"
+	}
+
 	cpuType := "host"
 
 	// Handle CPU flags.
@@ -1586,6 +1591,7 @@ func (d *qemu) start(stateful bool, op *operationlock.InstanceOperation) error {
 		"-name", d.Name(),
 		"-uuid", instUUID,
 		"-daemonize",
+		"-rtc", rtcBase,
 		"-cpu", cpuType,
 		"-nographic",
 		"-serial", "chardev:console",
@@ -3340,11 +3346,16 @@ func (d *qemu) deviceBootPriorities(base int) (map[string]int, error) {
 	return sortedDevs, nil
 }
 
+// windowsOS return whether the image is windows OS.
+func (d *qemu) windowsOS() bool {
+	return strings.Contains(strings.ToLower(d.expandedConfig["image.os"]), "windows")
+}
+
 // generateQemuConfig generates the QEMU configuration.
 func (d *qemu) generateQemuConfig(cpuInfo *cpuTopology, mountInfo *storagePools.MountInfo, busName string, vsockFD int, devConfs []*deviceConfig.RunConfig, fdFiles *[]*os.File) ([]monitorHook, error) {
 	var monHooks []monitorHook
 
-	isWindows := strings.Contains(strings.ToLower(d.expandedConfig["image.os"]), "windows")
+	isWindows := d.windowsOS()
 	conf := qemuBase(&qemuBaseOpts{d.Architecture(), util.IsTrue(d.expandedConfig["security.iommu"])})
 
 	err := d.addCPUMemoryConfig(&conf, cpuInfo)