rate-limiter: check if hypervisor supports built-in rate limiter

As for some hypervisors, like firecracker, they support built-in rate limiter
to control network I/O bandwidth on VMM level. And for some hypervisors, like qemu,
they don't.

Fixes: #250

Signed-off-by: Penny Zheng <penny.zheng@arm.com>

src/runtime/virtcontainers/acrn.go

@@ -811,3 +811,7 @@ func (a *Acrn) loadInfo() error {
 	}
 	return nil
 }
+
+func (a *Acrn) isRateLimiterBuiltin() bool {
+	return false
+}

src/runtime/virtcontainers/clh.go

@@ -1210,3 +1210,7 @@ func (clh *cloudHypervisor) vmInfo() (chclient.VmInfo, error) {
 	return info, openAPIClientError(err)
 
 }
+
+func (clh *cloudHypervisor) isRateLimiterBuiltin() bool {
+	return false
+}

src/runtime/virtcontainers/fc.go

@@ -25,12 +25,12 @@ import (
 
 	"github.com/kata-containers/kata-containers/src/runtime/virtcontainers/device/config"
 	persistapi "github.com/kata-containers/kata-containers/src/runtime/virtcontainers/persist/api"
+	kataclient "github.com/kata-containers/kata-containers/src/runtime/virtcontainers/pkg/agent/protocols/client"
 	"github.com/kata-containers/kata-containers/src/runtime/virtcontainers/pkg/firecracker/client"
 	models "github.com/kata-containers/kata-containers/src/runtime/virtcontainers/pkg/firecracker/client/models"
 	ops "github.com/kata-containers/kata-containers/src/runtime/virtcontainers/pkg/firecracker/client/operations"
 	"github.com/kata-containers/kata-containers/src/runtime/virtcontainers/types"
 	"github.com/kata-containers/kata-containers/src/runtime/virtcontainers/utils"
-	kataclient "github.com/kata-containers/kata-containers/src/runtime/virtcontainers/pkg/agent/protocols/client"
 
 	"github.com/blang/semver"
 	"github.com/containerd/console"
@@ -1212,3 +1212,7 @@ func (fc *firecracker) watchConsole() (*os.File, error) {
 
 	return stdio, nil
 }
+
+func (fc *firecracker) isRateLimiterBuiltin() bool {
+	return true
+}

src/runtime/virtcontainers/hypervisor.go

@@ -802,4 +802,7 @@ type hypervisor interface {
 
 	// generate the socket to communicate the host and guest
 	generateSocket(id string, useVsock bool) (interface{}, error)
+
+	// check if hypervisor supports built-in rate limiter.
+	isRateLimiterBuiltin() bool
 }

src/runtime/virtcontainers/mock_hypervisor.go

@@ -128,3 +128,7 @@ func (m *mockHypervisor) check() error {
 func (m *mockHypervisor) generateSocket(id string, useVsock bool) (interface{}, error) {
 	return types.Socket{HostPath: "/tmp/socket", Name: "socket"}, nil
 }
+
+func (m *mockHypervisor) isRateLimiterBuiltin() bool {
+	return false
+}

src/runtime/virtcontainers/qemu.go

@@ -2266,3 +2266,7 @@ func (q *qemu) check() error {
 func (q *qemu) generateSocket(id string, useVsock bool) (interface{}, error) {
 	return generateVMSocket(id, useVsock, q.store.RunVMStoragePath())
 }
+
+func (q *qemu) isRateLimiterBuiltin() bool {
+	return false
+}