libcontainer/intelrdt: verify ClosID existence

Check that the ClosID directory pre-exists if no L3 or MB schema has
been specified. Conform with the following line from runtime-spec
(config-linux):

  If closID is set, and neither of l3CacheSchema and memBwSchema are
  set, runtime MUST check if corresponding pre-configured directory
  closID is present in mounted resctrl. If such pre-configured directory
  closID exists, runtime MUST assign container to this closID and
  generate an error if directory does not exist.

Add a TODO note for verifying existing schemata against L3/MB
parameters.

Signed-off-by: Markus Lehtonen <[email protected]>

libcontainer/intelrdt/intelrdt.go

@@ -201,7 +201,6 @@ var (
 )
 
 type intelRdtData struct {
- root string
  config *configs.Config
  pid int
 }
@@ -563,6 +562,14 @@ func (m *intelRdtManager) Apply(pid int) (err error) {
  m.mu.Lock()
  defer m.mu.Unlock()
 
+ if m.config.IntelRdt.ClosID != "" && m.config.IntelRdt.L3CacheSchema == "" && m.config.IntelRdt.MemBwSchema == "" {
+ // Check that the CLOS exists, i.e. it has been pre-configured to
+ // conform with the runtime spec
+ if _, err := os.Stat(path); err != nil {
+ return fmt.Errorf("clos dir not accessible (must be pre-created when l3CacheSchema and memBwSchema are empty): %w", err)
+ }
+ }
+
  if err := os.MkdirAll(path, 0o755); err != nil {
  return NewLastCmdError(err)
  }
@@ -738,6 +745,12 @@ func (m *intelRdtManager) Set(container *configs.Config) error {
  l3CacheSchema := container.IntelRdt.L3CacheSchema
  memBwSchema := container.IntelRdt.MemBwSchema
 
+ // TODO: verify that l3CacheSchema and/or memBwSchema match the
+ // existing schemata if ClosID has been specified. This is a more
+ // involved than reading the file and doing plain string comparison as
+ // the value written in does not necessarily match what gets read out
+ // (leading zeros, cache id ordering etc).
+
  // Write a single joint schema string to schemata file
  if l3CacheSchema != "" && memBwSchema != "" {
  if err := writeFile(path, "schemata", l3CacheSchema+"\n"+memBwSchema); err != nil {

libcontainer/intelrdt/intelrdt_test.go

@@ -4,6 +4,8 @@ package intelrdt
 
 import (
  "io"
+ "os"
+ "path/filepath"
  "strings"
  "testing"
 )
@@ -113,6 +115,36 @@ func TestIntelRdtSetMemBwScSchema(t *testing.T) {
  }
 }
 
+func TestApply(t *testing.T) {
+ helper := NewIntelRdtTestUtil(t)
+ defer helper.cleanup()
+
+ const closID = "test-clos"
+
+ helper.IntelRdtData.config.IntelRdt.ClosID = closID
+ intelrdt := NewManager(helper.IntelRdtData.config, "", helper.IntelRdtPath)
+ if err := intelrdt.Apply(1234); err == nil {
+ t.Fatal("unexpected success when applying pid")
+ }
+ if _, err := os.Stat(filepath.Join(helper.IntelRdtPath, closID)); err == nil {
+ t.Fatal("closid dir should not exist")
+ }
+
+ // Dir should be created if some schema has been specified
+ intelrdt.(*intelRdtManager).config.IntelRdt.L3CacheSchema = "L3:0=f"
+ if err := intelrdt.Apply(1235); err != nil {
+ t.Fatalf("Apply() failed: %v", err)
+ }
+
+ pids, err := getIntelRdtParamString(intelrdt.GetPath(), "tasks")
+ if err != nil {
+ t.Fatalf("failed to read tasks file: %v", err)
+ }
+ if pids != "1235" {
+ t.Fatalf("unexpected tasks file, expected '1235', got %q", pids)
+ }
+}
+
 const (
  mountinfoValid = `18 40 0:18 / /sys rw,nosuid,nodev,noexec,relatime shared:6 - sysfs sysfs rw
 19 40 0:3 / /proc rw,nosuid,nodev,noexec,relatime shared:5 - proc proc rw

libcontainer/intelrdt/util_test.go

@@ -38,8 +38,8 @@ func NewIntelRdtTestUtil(t *testing.T) *intelRdtTestUtil {
  if err != nil {
  t.Fatal(err)
  }
- d.root = tempDir
- testIntelRdtPath := filepath.Join(d.root, "resctrl")
+ intelRdtRoot = tempDir
+ testIntelRdtPath := filepath.Join(tempDir, "resctrl")
  if err != nil {
  t.Fatal(err)
  }
@@ -53,6 +53,7 @@ func NewIntelRdtTestUtil(t *testing.T) *intelRdtTestUtil {
 }
 
 func (c *intelRdtTestUtil) cleanup() {
+ intelRdtRoot = ""
  os.RemoveAll(c.tempDir)
 }