Attach display adapters to Windows guests

lib/hypervisor/config.go

@@ -18,6 +18,7 @@ type VMConfig struct {
 
 	// Console
 	SerialLogPath string
+	Display       *DisplayConfig
 
 	// Vsock
 	VsockCID    int64
@@ -41,6 +42,12 @@ type VMConfig struct {
 	EnableRosetta bool
 }
 
+// DisplayConfig describes an optional virtual display adapter.
+type DisplayConfig struct {
+	Device     string
+	SocketPath string
+}
+
 // GuestMemoryConfig contains hypervisor-agnostic guest memory feature toggles.
 type GuestMemoryConfig struct {
 	EnableBalloon     bool

lib/hypervisor/qemu/config.go

@@ -151,8 +151,14 @@ func buildArgs(cfg hypervisor.VMConfig, machine MachineType) []string {
 		args = append(args, "-serial", "stdio")
 	}
 
-	// No graphics
-	args = append(args, "-nographic")
+	if cfg.Display != nil {
+		args = append(args, "-device", cfg.Display.Device, "-display", "none")
+		if cfg.Display.SocketPath != "" {
+			args = append(args, "-vnc", "unix:"+cfg.Display.SocketPath)
+		}
+	} else {
+		args = append(args, "-nographic")
+	}
 
 	// Disable default devices we don't need
 	args = append(args, "-nodefaults")

lib/hypervisor/qemu/config_test.go

@@ -49,6 +49,25 @@ func TestBuildArgs_Basic(t *testing.T) {
 	assert.Contains(t, args, "-nographic")
 }
 
+func TestBuildArgs_Display(t *testing.T) {
+	cfg := hypervisor.VMConfig{
+		VCPUs:       2,
+		MemoryBytes: 1024 * 1024 * 1024,
+		Display: &hypervisor.DisplayConfig{
+			Device:     "VGA",
+			SocketPath: "/instance/display.sock",
+		},
+	}
+
+	args := BuildArgs(cfg)
+	assert.Contains(t, args, "VGA")
+	assert.Contains(t, args, "-display")
+	assert.Contains(t, args, "none")
+	assert.Contains(t, args, "-vnc")
+	assert.Contains(t, args, "unix:/instance/display.sock")
+	assert.NotContains(t, args, "-nographic")
+}
+
 func TestBuildArgs_Disks(t *testing.T) {
 	cfg := hypervisor.VMConfig{
 		VCPUs:       1,

lib/instances/windows.go

@@ -218,9 +218,13 @@ func (m *manager) buildWindowsHypervisorConfig(inst *Instance, image *images.Ima
 		Disks:         []hypervisor.DiskConfig{{Path: m.paths.InstanceWindowsDisk(inst.Id), Format: hypervisor.DiskFormatQCOW2, IOBps: ioBps, IOBurstBps: burstBps}},
 		Networks:      networks,
 		SerialLogPath: m.paths.InstanceAppLog(inst.Id),
-		VsockCID:      inst.VsockCID,
-		VsockSocket:   inst.VsockSocket,
-		BootMode:      hypervisor.BootModeUEFI,
+		Display: &hypervisor.DisplayConfig{
+			Device:     "VGA",
+			SocketPath: m.paths.InstanceSocket(inst.Id, "display.sock"),
+		},
+		VsockCID:    inst.VsockCID,
+		VsockSocket: inst.VsockSocket,
+		BootMode:    hypervisor.BootModeUEFI,
 		Firmware: &hypervisor.FirmwareConfig{
 			CodePath:   m.paths.InstanceOVMFCode(inst.Id),
 			VarsPath:   m.paths.InstanceOVMFVars(inst.Id),

lib/instances/windows_test.go

@@ -127,6 +127,9 @@ func TestBuildWindowsHypervisorConfig(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, hypervisor.BootModeUEFI, config.BootMode)
 	assert.True(t, config.Firmware.SecureBoot)
+	require.NotNil(t, config.Display)
+	assert.Equal(t, "VGA", config.Display.Device)
+	assert.Equal(t, p.InstanceSocket(stored.Id, "display.sock"), config.Display.SocketPath)
 	assert.Equal(t, p.InstanceTPMDir(stored.Id), config.TPM.StateDir)
 	require.Len(t, config.Disks, 1)
 	assert.Equal(t, hypervisor.DiskFormatQCOW2, config.Disks[0].Format)