runtime: Allow and require no initrd for SE

Previously, it was not permitted to have neither an initrd nor an image.
However, this is the exact config to use for Secure Execution, where the
initrd is part of the image to be specified as `-kernel`. Require the
configuration of no initrd for Secure Execution.

Also
- remove redundant code for image/initrd checking -- no need to check in
  `newQemuHypervisorConfig` (calling) when it is also checked in
  `getInitrdAndImage` (called)
- use `QemuCCWVirtio` constant when possible

Fixes: #3922
Signed-off-by: Jakob Naucke <jakob.naucke@ibm.com>

src/runtime/pkg/katautils/config.go

@@ -469,11 +469,13 @@ func (h hypervisor) getInitrdAndImage() (initrd string, image string, err error)
 
 	image, errImage := h.image()
 
-	if image != "" && initrd != "" {
+	if h.ConfidentialGuest && h.MachineType == vc.QemuCCWVirtio {
+		if image != "" || initrd != "" {
+			return "", "", errors.New("Neither the image nor initrd path may be set for Secure Execution")
+		}
+	} else if image != "" && initrd != "" {
 		return "", "", errors.New("having both an image and an initrd defined in the configuration file is not supported")
-	}
-
-	if errInitrd != nil && errImage != nil {
+	} else if errInitrd != nil && errImage != nil {
 		return "", "", fmt.Errorf("Either initrd or image must be set to a valid path (initrd: %v) (image: %v)", errInitrd, errImage)
 	}
 
@@ -605,16 +607,6 @@ func newQemuHypervisorConfig(h hypervisor) (vc.HypervisorConfig, error) {
 		return vc.HypervisorConfig{}, err
 	}
 
-	if image != "" && initrd != "" {
-		return vc.HypervisorConfig{},
-			errors.New("having both an image and an initrd defined in the configuration file is not supported")
-	}
-
-	if image == "" && initrd == "" {
-		return vc.HypervisorConfig{},
-			errors.New("either image or initrd must be defined in the configuration file")
-	}
-
 	firmware, err := h.firmware()
 	if err != nil {
 		return vc.HypervisorConfig{}, err

src/runtime/virtcontainers/hypervisor.go

@@ -527,17 +527,19 @@ func (conf *HypervisorConfig) CheckTemplateConfig() error {
 }
 
 func (conf *HypervisorConfig) Valid() error {
-
 	// Kata specific checks. Should be done outside the hypervisor
 	if conf.KernelPath == "" {
 		return fmt.Errorf("Missing kernel path")
 	}
 
-	if conf.ImagePath == "" && conf.InitrdPath == "" {
+	if conf.ConfidentialGuest && conf.HypervisorMachineType == QemuCCWVirtio {
+		if conf.ImagePath != "" || conf.InitrdPath != "" {
+			fmt.Println("yes, failing")
+			return fmt.Errorf("Neither the image or initrd path may be set for Secure Execution")
+		}
+	} else if conf.ImagePath == "" && conf.InitrdPath == "" {
 		return fmt.Errorf("Missing image and initrd path")
-	}
-
-	if conf.ImagePath != "" && conf.InitrdPath != "" {
+	} else if conf.ImagePath != "" && conf.InitrdPath != "" {
 		return fmt.Errorf("Image and initrd path cannot be both set")
 	}
 
@@ -559,7 +561,7 @@ func (conf *HypervisorConfig) Valid() error {
 
 	if conf.BlockDeviceDriver == "" {
 		conf.BlockDeviceDriver = defaultBlockDriver
-	} else if conf.BlockDeviceDriver == config.VirtioBlock && conf.HypervisorMachineType == "s390-ccw-virtio" {
+	} else if conf.BlockDeviceDriver == config.VirtioBlock && conf.HypervisorMachineType == QemuCCWVirtio {
 		conf.BlockDeviceDriver = config.VirtioBlockCCW
 	}
 

src/runtime/virtcontainers/hypervisor_test.go

@@ -144,6 +144,18 @@ func TestHypervisorConfigBothInitrdAndImage(t *testing.T) {
 	testHypervisorConfigValid(t, hypervisorConfig, false)
 }
 
+func TestHypervisorConfigSecureExecution(t *testing.T) {
+	hypervisorConfig := &HypervisorConfig{
+		KernelPath:            fmt.Sprintf("%s/%s", testDir, testKernel),
+		InitrdPath:            fmt.Sprintf("%s/%s", testDir, testInitrd),
+		ConfidentialGuest:     true,
+		HypervisorMachineType: QemuCCWVirtio,
+	}
+
+	// Secure Execution should only specify a kernel (encrypted image contains all components)
+	testHypervisorConfigValid(t, hypervisorConfig, false)
+}
+
 func TestHypervisorConfigValidTemplateConfig(t *testing.T) {
 	hypervisorConfig := &HypervisorConfig{
 		KernelPath:       fmt.Sprintf("%s/%s", testDir, testKernel),

src/runtime/virtcontainers/qemu.go

@@ -1841,7 +1841,7 @@ func (q *qemu) hotplugAddCPUs(amount uint32) (uint32, error) {
 		threadID := fmt.Sprintf("%d", hc.Properties.Thread)
 
 		// If CPU type is IBM pSeries, Z or arm virt, we do not set socketID and threadID
-		if machine.Type == "pseries" || machine.Type == "s390-ccw-virtio" || machine.Type == "virt" {
+		if machine.Type == "pseries" || machine.Type == QemuCCWVirtio || machine.Type == "virt" {
 			socketID = ""
 			threadID = ""
 			dieID = ""