libcontainer: intelrdt: add update command support

Add runc update command support for Intel RDT/CAT.

for example:
runc update --l3-cache-schema "L3:0=f;1=f" <container-id>

Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com>

update.go

@@ -112,6 +112,10 @@ 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 +258,21 @@ other options are ignored.
 		config.Cgroups.Resources.MemorySwap = *r.Memory.Swap
 		config.Cgroups.Resources.PidsLimit = r.Pids.Limit
 
+		// If intelRdt is not specified in config
+		if config.IntelRdt == nil {
+			return fmt.Errorf("failed to update l3-cache-schema: intelRdt.l3CacheSchema is not specified in config")
+		}
+
+		i := specs.LinuxIntelRdt{
+			L3CacheSchema: "",
+		}
+
+		if val := context.String("l3-cache-schema"); val != "" {
+			i.L3CacheSchema = val
+		}
+
+		config.IntelRdt.L3CacheSchema = i.L3CacheSchema
+
 		return container.Set(config)
 	},
 }