libcontainer: intelrdt: add update command support

libcontainer/factory_linux.go

@@ -213,8 +213,7 @@ func (l *LinuxFactory) Create(id string, config *configs.Config) (Container, err
 		newgidmapPath: l.NewgidmapPath,
 		cgroupManager: l.NewCgroupsManager(config.Cgroups, nil),
 	}
-	c.intelRdtManager = nil
-	if intelrdt.IsEnabled() && c.config.IntelRdt != nil {
+	if intelrdt.IsEnabled() {
 		c.intelRdtManager = l.NewIntelRdtManager(config, id, "")
 	}
 	c.state = &stoppedState{c: c}
@@ -256,8 +255,7 @@ func (l *LinuxFactory) Load(id string) (Container, error) {
 	if err := c.refreshState(); err != nil {
 		return nil, err
 	}
-	c.intelRdtManager = nil
-	if intelrdt.IsEnabled() && c.config.IntelRdt != nil {
+	if intelrdt.IsEnabled() {
 		c.intelRdtManager = l.NewIntelRdtManager(&state.Config, id, state.IntelRdtPath)
 	}
 	return c, nil

libcontainer/intelrdt/intelrdt.go

@@ -401,6 +401,10 @@ func GetIntelRdtPath(id string) (string, error) {
 
 // Applies Intel RDT configuration to the process with the specified pid
 func (m *IntelRdtManager) Apply(pid int) (err error) {
+	// If intelRdt is not specified in config, we do nothing
+	if m.Config.IntelRdt == nil {
+		return nil
+	}
 	d, err := getIntelRdtData(m.Config, pid)
 	if err != nil && !IsNotFound(err) {
 		return err

update.go

@@ -9,6 +9,8 @@ import (
 	"strconv"
 
 	"github.com/docker/go-units"
+	"github.com/opencontainers/runc/libcontainer/configs"
+	"github.com/opencontainers/runc/libcontainer/intelrdt"
 	"github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/urfave/cli"
 )
@@ -112,6 +114,10 @@ other options are ignored.
 			Name:  "pids-limit",
 			Usage: "Maximum number of pids allowed in the container",
 		},
+		cli.StringFlag{
+			Name:  "l3-cache-schema",
+			Usage: "The string of Intel RDT/CAT L3 cache schema",
+		},
 	},
 	Action: func(context *cli.Context) error {
 		if err := checkArgs(context, 1, exactArgs); err != nil {
@@ -254,6 +260,34 @@ other options are ignored.
 		config.Cgroups.Resources.MemorySwap = *r.Memory.Swap
 		config.Cgroups.Resources.PidsLimit = r.Pids.Limit
 
+		// Update Intel RDT/CAT
+		if val := context.String("l3-cache-schema"); val != "" {
+			if !intelrdt.IsEnabled() {
+				return fmt.Errorf("Intel RDT: l3 cache schema is not enabled")
+			}
+
+			// If intelRdt is not specified in original configuration, we just don't
+			// Apply() to create intelRdt group or attach tasks for this container.
+			// In update command, we could re-enable through IntelRdtManager.Apply()
+			// and then update intelrdt constraint.
+			if config.IntelRdt == nil {
+				state, err := container.State()
+				if err != nil {
+					return err
+				}
+				config.IntelRdt = &configs.IntelRdt{}
+				intelRdtManager := intelrdt.IntelRdtManager{
+					Config: &config,
+					Id:     container.ID(),
+					Path:   state.IntelRdtPath,
+				}
+				if err := intelRdtManager.Apply(state.InitProcessPid); err != nil {
+					return err
+				}
+			}
+			config.IntelRdt.L3CacheSchema = val
+		}
+
 		return container.Set(config)
 	},
 }