hypervisors: Confidential Guests do not support Device hotplug

Similarly to VCPUs hotplug, Confidential Guests also do not support
Device hotplug.

Let's make it clear in the documentation and guard the code on both QEMU
and Cloud Hypervisor side to ensure we don't advertise Device hotplug as
being supported when running Confidential Guests.

Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>

src/runtime/config/configuration-clh.toml.in

@@ -24,6 +24,7 @@ image = "@IMAGEPATH@"
 # Known limitations:
 # * Does not work by design:
 #   - CPU Hotplug 
+#   - Device Hotplug
 #
 # Default false
 # confidential_guest = true

src/runtime/config/configuration-qemu.toml.in

@@ -25,6 +25,7 @@ machine_type = "@MACHINETYPE@"
 # Known limitations:
 # * Does not work by design:
 #   - CPU Hotplug 
+#   - Device Hotplug
 #
 # Default false
 # confidential_guest = true

src/runtime/virtcontainers/clh.go

@@ -589,6 +589,10 @@ func (clh *cloudHypervisor) HotplugAddDevice(ctx context.Context, devInfo interf
 	span, _ := katatrace.Trace(ctx, clh.Logger(), "HotplugAddDevice", clhTracingTags, map[string]string{"sandbox_id": clh.id})
 	defer span.End()
 
+	if clh.config.ConfidentialGuest {
+		return nil, errors.New("Device hotplug addition is not supported in confidential mode")
+	}
+
 	switch devType {
 	case BlockDev:
 		drive := devInfo.(*config.BlockDrive)
@@ -606,6 +610,10 @@ func (clh *cloudHypervisor) HotplugRemoveDevice(ctx context.Context, devInfo int
 	span, _ := katatrace.Trace(ctx, clh.Logger(), "HotplugRemoveDevice", clhTracingTags, map[string]string{"sandbox_id": clh.id})
 	defer span.End()
 
+	if clh.config.ConfidentialGuest {
+		return nil, errors.New("Device hotplug addition is not supported in confidential mode")
+	}
+
 	var deviceID string
 
 	switch devType {
@@ -860,7 +868,9 @@ func (clh *cloudHypervisor) Capabilities(ctx context.Context) types.Capabilities
 	clh.Logger().WithField("function", "Capabilities").Info("get Capabilities")
 	var caps types.Capabilities
 	caps.SetFsSharingSupport()
+	if !clh.config.ConfidentialGuest {
 		caps.SetBlockDeviceHotplugSupport()
+	}
 	return caps
 }
 

src/runtime/virtcontainers/qemu_amd64.go

@@ -153,8 +153,9 @@ func newQemuArch(config HypervisorConfig) (qemuArch, error) {
 func (q *qemuAmd64) capabilities() types.Capabilities {
 	var caps types.Capabilities
 
-	if q.qemuMachine.Type == QemuQ35 ||
+	if (q.qemuMachine.Type == QemuQ35 ||
-		q.qemuMachine.Type == QemuVirt {
+		q.qemuMachine.Type == QemuVirt) &&
+		q.protection == noneProtection {
 		caps.SetBlockDeviceHotplugSupport()
 	}
 

src/runtime/virtcontainers/qemu_arch_base.go

@@ -277,7 +277,9 @@ func (q *qemuArchBase) kernelParameters(debug bool) []Param {
 
 func (q *qemuArchBase) capabilities() types.Capabilities {
 	var caps types.Capabilities
+	if q.protection == noneProtection {
 		caps.SetBlockDeviceHotplugSupport()
+	}
 	caps.SetMultiQueueSupport()
 	caps.SetFsSharingSupport()
 	return caps

src/runtime/virtcontainers/qemu_ppc64le.go

@@ -96,7 +96,8 @@ func (q *qemuPPC64le) capabilities() types.Capabilities {
 	var caps types.Capabilities
 
 	// pseries machine type supports hotplugging drives
-	if q.qemuMachine.Type == QemuPseries {
+	if q.qemuMachine.Type == QemuPseries &&
+		q.protection == noneProtection {
 		caps.SetBlockDeviceHotplugSupport()
 	}