libcontainer: add support for Intel RDT/CAT in runc

About Intel RDT/CAT feature:
Intel platforms with new Xeon CPU support Intel Resource Director Technology
(RDT). Cache Allocation Technology (CAT) is a sub-feature of RDT, which
currently supports L3 cache resource allocation.

This feature provides a way for the software to restrict cache allocation to a
defined 'subset' of L3 cache which may be overlapping with other 'subsets'.
The different subsets are identified by class of service (CLOS) and each CLOS
has a capacity bitmask (CBM).

For more information about Intel RDT/CAT can be found in the section 17.17
of Intel Software Developer Manual.

About Intel RDT/CAT kernel interface:
In Linux kernel, the interface is defined and exposed via "resource control"
filesystem, which is a "cgroup-like" interface.

Comparing with cgroups, it has similar process management lifecycle and
interfaces in a container. But unlike cgroups' hierarchy, it has single level
filesystem layout.

Intel RDT "resource control" filesystem hierarchy:
mount -t resctrl resctrl /sys/fs/resctrl
tree /sys/fs/resctrl
/sys/fs/resctrl/
|-- info
|   |-- L3
|       |-- cbm_mask
|       |-- num_closids
|-- cpus
|-- schemata
|-- tasks
|-- <container_id>
    |-- cpus
    |-- schemata
    |-- tasks

For runc, we can make use of `tasks` and `schemata` configuration for L3 cache
resource constraints.

 The file `tasks` has a list of tasks that belongs to this group (e.g.,
<container_id>" group). Tasks can be added to a group by writing the task ID
to the "tasks" file  (which will automatically remove them from the previous
group to which they belonged). New tasks created by fork(2) and clone(2) are
added to the same group as their parent. If a pid is not in any sub group, it
Is in root group.

The file `schemata` has allocation bitmasks/values for L3 cache on each socket,
which contains L3 cache id and capacity bitmask (CBM).
	Format: "L3:<cache_id0>=<cbm0>;<cache_id1>=<cbm1>;..."
For example, on a two-socket machine, L3's schema line could be `L3:0=ff;1=c0`
which means L3 cache id 0's CBM is 0xff, and L3 cache id 1's CBM is 0xc0.

The valid L3 cache CBM is a *contiguous bits set* and number of bits that can
be set is less than the max bit. The max bits in the CBM is varied among
supported Intel Xeon platforms. In Intel RDT "resource control" filesystem
layout, the CBM in a group should be a subset of the CBM in root. Kernel will
check if it is valid when writing. e.g., 0xfffff in root indicates the max bits
of CBM is 20 bits, which mapping to entire L3 cache capacity. Some valid CBM
values to set in a group: 0xf, 0xf0, 0x3ff, 0x1f00 and etc.

For more information about Intel RDT/CAT kernel interface:
https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/commit/?h=x86/cache&id=f20e57892806ad244eaec7a7ae365e78fee53377

An example for runc:
There are two L3 caches in the two-socket machine, the default CBM is 0xfffff
and the max CBM length is 20 bits. This configuration assigns 4/5 of L3 cache
id 0 and the whole L3 cache id 1 for the container:

"linux": {
	"resources": {
		"intelRdt": {
			"l3CacheSchema": "L3:0=ffff0;1=fffff"
		}
	}
}

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

events.go

@@ -24,11 +24,12 @@ type event struct {
 
 // stats is the runc specific stats structure for stability when encoding and decoding stats.
 type stats struct {
-	Cpu     cpu                `json:"cpu"`
-	Memory  memory             `json:"memory"`
-	Pids    pids               `json:"pids"`
-	Blkio   blkio              `json:"blkio"`
-	Hugetlb map[string]hugetlb `json:"hugetlb"`
+	Cpu      cpu                `json:"cpu"`
+	Memory   memory             `json:"memory"`
+	Pids     pids               `json:"pids"`
+	Blkio    blkio              `json:"blkio"`
+	Hugetlb  map[string]hugetlb `json:"hugetlb"`
+	IntelRdt intelRdt           `json:"intelRdt"`
 }
 
 type hugetlb struct {
@@ -95,6 +96,12 @@ type memory struct {
 	Raw       map[string]uint64 `json:"raw,omitempty"`
 }
 
+type intelRdt struct {
+	// The read-only default "schemas" in root, for reference
+	L3CacheSchemaRoot string `json:"l3CacheSchemaRoot,omitempty"`
+	L3CacheSchema     string `json:"l3CacheSchema,omitempty"`
+}
+
 var eventsCommand = cli.Command{
 	Name:  "events",
 	Usage: "display container events such as OOM notifications, cpu, memory, and IO usage statistics",
@@ -223,6 +230,10 @@ func convertLibcontainerStats(ls *libcontainer.Stats) *stats {
 	for k, v := range cg.HugetlbStats {
 		s.Hugetlb[k] = convertHugtlb(v)
 	}
+
+	is := cg.IntelRdtStats
+	s.IntelRdt.L3CacheSchemaRoot = is.IntelRdtRootStats.L3CacheSchema
+	s.IntelRdt.L3CacheSchema = is.IntelRdtGroupStats.L3CacheSchema
 	return &s
 }
 

libcontainer/cgroups/cgroups.go

@@ -39,6 +39,9 @@ type Manager interface {
 
 	// Sets the cgroup as configured.
 	Set(container *configs.Config) error
+
+	// Get non-cgroup resource path
+	GetResourcePath() string
 }
 
 type NotFoundError struct {

libcontainer/cgroups/fs/apply_raw.go

@@ -31,6 +31,7 @@ var (
 		&PerfEventGroup{},
 		&FreezerGroup{},
 		&NameGroup{GroupName: "name=systemd", Join: true},
+		// If Intel RDT is enabled, will append IntelRdtGroup later
 	}
 	HugePageSizes, _ = cgroups.GetHugePageSize()
 )
@@ -62,9 +63,11 @@ type subsystem interface {
 }
 
 type Manager struct {
-	mu      sync.Mutex
-	Cgroups *configs.Cgroup
-	Paths   map[string]string
+	mu           sync.Mutex
+	Cgroups      *configs.Cgroup
+	Paths        map[string]string
+	ContainerId  string
+	ResourcePath string
 }
 
 // The absolute path to the root of the cgroup hierarchies.
@@ -94,10 +97,11 @@ func getCgroupRoot() (string, error) {
 }
 
 type cgroupData struct {
-	root      string
-	innerPath string
-	config    *configs.Cgroup
-	pid       int
+	root        string
+	innerPath   string
+	config      *configs.Cgroup
+	pid         int
+	containerId string
 }
 
 func (m *Manager) Apply(pid int) (err error) {
@@ -109,7 +113,7 @@ func (m *Manager) Apply(pid int) (err error) {
 
 	var c = m.Cgroups
 
-	d, err := getCgroupData(m.Cgroups, pid)
+	d, err := getCgroupData(m.Cgroups, pid, m.ContainerId)
 	if err != nil {
 		return err
 	}
@@ -131,23 +135,38 @@ func (m *Manager) Apply(pid int) (err error) {
 	}
 
 	paths := make(map[string]string)
+
+	// If Intel RDT is enabled, append IntelRdtGroup to subsystems
+	if IsIntelRdtEnabled() && m.Cgroups.Resources.IntelRdtL3CacheSchema != "" {
+		subsystems = append(subsystems, &IntelRdtGroup{})
+		intelRdtPath, err := GetIntelRdtPath(m.ContainerId)
+		if err != nil {
+			return err
+		}
+		m.ResourcePath = intelRdtPath
+	}
+
 	for _, sys := range subsystems {
 		if err := sys.Apply(d); err != nil {
 			return err
 		}
-		// TODO: Apply should, ideally, be reentrant or be broken up into a separate
-		// create and join phase so that the cgroup hierarchy for a container can be
-		// created then join consists of writing the process pids to cgroup.procs
-		p, err := d.path(sys.Name())
-		if err != nil {
-			// The non-presence of the devices subsystem is
-			// considered fatal for security reasons.
-			if cgroups.IsNotFound(err) && sys.Name() != "devices" {
-				continue
+
+		// Intel RDT "resource control" filesystem is not in cgroup path
+		if sys.Name() != "intel_rdt" {
+			// TODO: Apply should, ideally, be reentrant or be broken up into a separate
+			// create and join phase so that the cgroup hierarchy for a container can be
+			// created then join consists of writing the process pids to cgroup.procs
+			p, err := d.path(sys.Name())
+			if err != nil {
+				// The non-presence of the devices subsystem is
+				// considered fatal for security reasons.
+				if cgroups.IsNotFound(err) && sys.Name() != "devices" {
+					continue
+				}
+				return err
 			}
-			return err
+			paths[sys.Name()] = p
 		}
-		paths[sys.Name()] = p
 	}
 	m.Paths = paths
 	return nil
@@ -163,6 +182,12 @@ func (m *Manager) Destroy() error {
 		return err
 	}
 	m.Paths = make(map[string]string)
+
+	// Intel RDT "resource control" filesystem
+	if m.ResourcePath != "" {
+		return os.RemoveAll(m.ResourcePath)
+	}
+	m.ResourcePath = ""
 	return nil
 }
 
@@ -173,6 +198,13 @@ func (m *Manager) GetPaths() map[string]string {
 	return paths
 }
 
+func (m *Manager) GetResourcePath() string {
+	m.mu.Lock()
+	path := m.ResourcePath
+	m.mu.Unlock()
+	return path
+}
+
 func (m *Manager) GetStats() (*cgroups.Stats, error) {
 	m.mu.Lock()
 	defer m.mu.Unlock()
@@ -186,6 +218,24 @@ func (m *Manager) GetStats() (*cgroups.Stats, error) {
 			return nil, err
 		}
 	}
+
+	// Intel RDT "resource control" filesystem stats
+	if IsIntelRdtEnabled() && m.Cgroups.Resources.IntelRdtL3CacheSchema != "" {
+		intelRdtPath, err := GetIntelRdtPath(m.ContainerId)
+		if err != nil || !cgroups.PathExists(intelRdtPath) {
+			return nil, err
+		}
+		sys, err := subsystems.Get("intel_rdt")
+		if err == errSubsystemDoesNotExist {
+			// In case IntelRdtGroup is not appended to subsystems
+			subsystems = append(subsystems, &IntelRdtGroup{})
+		}
+		sys, _ = subsystems.Get("intel_rdt")
+		if err := sys.GetStats(intelRdtPath, stats); err != nil {
+			return nil, err
+		}
+	}
+
 	return stats, nil
 }
 
@@ -199,6 +249,9 @@ func (m *Manager) Set(container *configs.Config) error {
 	paths := m.GetPaths()
 	for _, sys := range subsystems {
 		path := paths[sys.Name()]
+		if sys.Name() == "intel_rdt" {
+			path = m.GetResourcePath()
+		}
 		if err := sys.Set(path, container.Cgroups); err != nil {
 			return err
 		}
@@ -241,7 +294,7 @@ func (m *Manager) GetAllPids() ([]int, error) {
 	return cgroups.GetAllPids(paths["devices"])
 }
 
-func getCgroupData(c *configs.Cgroup, pid int) (*cgroupData, error) {
+func getCgroupData(c *configs.Cgroup, pid int, containerId string) (*cgroupData, error) {
 	root, err := getCgroupRoot()
 	if err != nil {
 		return nil, err
@@ -262,10 +315,11 @@ func getCgroupData(c *configs.Cgroup, pid int) (*cgroupData, error) {
 	}
 
 	return &cgroupData{
-		root:      root,
-		innerPath: innerPath,
-		config:    c,
-		pid:       pid,
+		root:        root,
+		innerPath:   innerPath,
+		config:      c,
+		pid:         pid,
+		containerId: containerId,
 	}, nil
 }
 

libcontainer/cgroups/fs/apply_raw_test.go

@@ -20,7 +20,7 @@ func TestInvalidCgroupPath(t *testing.T) {
 		Path: "../../../../../../../../../../some/path",
 	}
 
-	data, err := getCgroupData(config, 0)
+	data, err := getCgroupData(config, 0, "")
 	if err != nil {
 		t.Errorf("couldn't get cgroup data: %v", err)
 	}
@@ -51,7 +51,7 @@ func TestInvalidAbsoluteCgroupPath(t *testing.T) {
 		Path: "/../../../../../../../../../../some/path",
 	}
 
-	data, err := getCgroupData(config, 0)
+	data, err := getCgroupData(config, 0, "")
 	if err != nil {
 		t.Errorf("couldn't get cgroup data: %v", err)
 	}
@@ -84,7 +84,7 @@ func TestInvalidCgroupParent(t *testing.T) {
 		Name:   "name",
 	}
 
-	data, err := getCgroupData(config, 0)
+	data, err := getCgroupData(config, 0, "")
 	if err != nil {
 		t.Errorf("couldn't get cgroup data: %v", err)
 	}
@@ -117,7 +117,7 @@ func TestInvalidAbsoluteCgroupParent(t *testing.T) {
 		Name:   "name",
 	}
 
-	data, err := getCgroupData(config, 0)
+	data, err := getCgroupData(config, 0, "")
 	if err != nil {
 		t.Errorf("couldn't get cgroup data: %v", err)
 	}
@@ -150,7 +150,7 @@ func TestInvalidCgroupName(t *testing.T) {
 		Name:   "../../../../../../../../../../some/path",
 	}
 
-	data, err := getCgroupData(config, 0)
+	data, err := getCgroupData(config, 0, "")
 	if err != nil {
 		t.Errorf("couldn't get cgroup data: %v", err)
 	}
@@ -184,7 +184,7 @@ func TestInvalidAbsoluteCgroupName(t *testing.T) {
 		Name:   "/../../../../../../../../../../some/path",
 	}
 
-	data, err := getCgroupData(config, 0)
+	data, err := getCgroupData(config, 0, "")
 	if err != nil {
 		t.Errorf("couldn't get cgroup data: %v", err)
 	}
@@ -217,7 +217,7 @@ func TestInvalidCgroupNameAndParent(t *testing.T) {
 		Name:   "../../../../../../../../../../some/path",
 	}
 
-	data, err := getCgroupData(config, 0)
+	data, err := getCgroupData(config, 0, "")
 	if err != nil {
 		t.Errorf("couldn't get cgroup data: %v", err)
 	}
@@ -250,7 +250,7 @@ func TestInvalidAbsoluteCgroupNameAndParent(t *testing.T) {
 		Name:   "/../../../../../../../../../../some/path",
 	}
 
-	data, err := getCgroupData(config, 0)
+	data, err := getCgroupData(config, 0, "")
 	if err != nil {
 		t.Errorf("couldn't get cgroup data: %v", err)
 	}