hypervisor: allow to return a slice of pids

so that for qemu, we can save and export virtiofsd pid,
and put it to the same cgroup as the qemu process.

Fixes: #1972
Signed-off-by: Peng Tao <bergwolf@hyper.sh>

virtcontainers/acrn.go

@@ -617,8 +617,8 @@ func (a *acrn) cleanup() error {
 	return nil
 }
 
-func (a *acrn) pid() int {
-	return a.info.PID
+func (a *acrn) getPids() []int {
+	return []int{a.info.PID}
 }
 
 func (a *acrn) fromGrpc(ctx context.Context, hypervisorConfig *HypervisorConfig, store *store.VCStore, j []byte) error {
@@ -639,7 +639,7 @@ func (a *acrn) storeInfo() error {
 }
 
 func (a *acrn) save() (s persistapi.HypervisorState) {
-	s.Pid = a.pid()
+	s.Pid = a.info.PID
 	s.Type = string(AcrnHypervisor)
 	s.UUID = a.state.UUID
 	return
@@ -651,7 +651,7 @@ func (a *acrn) load(s persistapi.HypervisorState) {
 }
 
 func (a *acrn) check() error {
-	if err := syscall.Kill(a.pid(), syscall.Signal(0)); err != nil {
+	if err := syscall.Kill(a.info.PID, syscall.Signal(0)); err != nil {
 		return errors.Wrapf(err, "failed to ping acrn process")
 	}
 

virtcontainers/cgroups.go

@@ -209,9 +209,9 @@ func (s *Sandbox) deleteCgroups() error {
 }
 
 func (s *Sandbox) constrainHypervisor(cgroup cgroups.Cgroup) error {
-	pid := s.hypervisor.pid()
-	if pid <= 0 {
-		return fmt.Errorf("Invalid hypervisor PID: %d", pid)
+	pids := s.hypervisor.getPids()
+	if len(pids) == 0 || pids[0] == 0 {
+		return fmt.Errorf("Invalid hypervisor PID: %+v", pids)
 	}
 
 	// Move hypervisor into cgroups without constraints,
@@ -222,9 +222,14 @@ func (s *Sandbox) constrainHypervisor(cgroup cgroups.Cgroup) error {
 	if err != nil {
 		return fmt.Errorf("Could not create cgroup %v: %v", path, err)
 	}
-
-	if err := noConstraintsCgroup.Add(cgroups.Process{Pid: pid}); err != nil {
-		return fmt.Errorf("Could not add hypervisor PID %d to cgroup %v: %v", pid, path, err)
+	for _, pid := range pids {
+		if pid <= 0 {
+			s.Logger().Warnf("Invalid hypervisor pid: %d", pid)
+			continue
+		}
+		if err := noConstraintsCgroup.Add(cgroups.Process{Pid: pid}); err != nil {
+			return fmt.Errorf("Could not add hypervisor PID %d to cgroup %v: %v", pid, path, err)
+		}
 	}
 
 	// when new container joins, new CPU could be hotplugged, so we

virtcontainers/fc.go

@@ -985,8 +985,8 @@ func (fc *firecracker) cleanup() error {
 	return nil
 }
 
-func (fc *firecracker) pid() int {
-	return fc.info.PID
+func (fc *firecracker) getPids() []int {
+	return []int{fc.info.PID}
 }
 
 func (fc *firecracker) fromGrpc(ctx context.Context, hypervisorConfig *HypervisorConfig, store *store.VCStore, j []byte) error {
@@ -998,7 +998,7 @@ func (fc *firecracker) toGrpc() ([]byte, error) {
 }
 
 func (fc *firecracker) save() (s persistapi.HypervisorState) {
-	s.Pid = fc.pid()
+	s.Pid = fc.info.PID
 	s.Type = string(FirecrackerHypervisor)
 	return
 }
@@ -1008,7 +1008,7 @@ func (fc *firecracker) load(s persistapi.HypervisorState) {
 }
 
 func (fc *firecracker) check() error {
-	if err := syscall.Kill(fc.pid(), syscall.Signal(0)); err != nil {
+	if err := syscall.Kill(fc.info.PID, syscall.Signal(0)); err != nil {
 		return errors.Wrapf(err, "failed to ping fc process")
 	}
 

virtcontainers/hypervisor.go

@@ -648,6 +648,14 @@ func RunningOnVMM(cpuInfoPath string) (bool, error) {
 	return false, fmt.Errorf("Couldn't find %q from %q output", flagsField, cpuInfoPath)
 }
 
+func getHypervisorPid(h hypervisor) int {
+	pids := h.getPids()
+	if len(pids) == 0 {
+		return 0
+	}
+	return pids[0]
+}
+
 // hypervisor is the virtcontainers hypervisor interface.
 // The default hypervisor implementation is Qemu.
 type hypervisor interface {
@@ -668,7 +676,9 @@ type hypervisor interface {
 	hypervisorConfig() HypervisorConfig
 	getThreadIDs() (vcpuThreadIDs, error)
 	cleanup() error
-	pid() int
+	// getPids returns a slice of hypervisor related process ids.
+	// The hypervisor pid must be put at index 0.
+	getPids() []int
 	fromGrpc(ctx context.Context, hypervisorConfig *HypervisorConfig, store *store.VCStore, j []byte) error
 	toGrpc() ([]byte, error)
 	check() error

virtcontainers/kata_agent.go

@@ -657,7 +657,7 @@ func (k *kataAgent) startProxy(sandbox *Sandbox) error {
 
 	proxyParams := proxyParams{
 		id:         sandbox.id,
-		hid:        sandbox.hypervisor.pid(),
+		hid:        getHypervisorPid(sandbox.hypervisor),
 		path:       sandbox.config.ProxyConfig.Path,
 		agentURL:   agentURL,
 		consoleURL: consoleURL,

virtcontainers/mock_hypervisor.go

@@ -104,8 +104,8 @@ func (m *mockHypervisor) cleanup() error {
 	return nil
 }
 
-func (m *mockHypervisor) pid() int {
-	return m.mockPid
+func (m *mockHypervisor) getPids() []int {
+	return []int{m.mockPid}
 }
 
 func (m *mockHypervisor) fromGrpc(ctx context.Context, hypervisorConfig *HypervisorConfig, store *store.VCStore, j []byte) error {

virtcontainers/persist/api/hypervisor.go

@@ -39,5 +39,6 @@ type HypervisorState struct {
 	// HotpluggedCPUs is the list of CPUs that were hot-added
 	HotpluggedVCPUs      []CPUDevice
 	HotpluggedMemory     int
+	VirtiofsdPid         int
 	HotplugVFIOOnRootBus bool
 }

virtcontainers/persist/api/version.go

@@ -15,5 +15,5 @@ const (
 	// If you can't be sure if the change in persistapi package
 	// requires a bump of CurPersistVersion or not, do it for peace!
 	// --@WeiZhang555
-	CurPersistVersion uint = 1
+	CurPersistVersion uint = 2
 )

virtcontainers/qemu.go

@@ -67,6 +67,7 @@ type QemuState struct {
 	HotpluggedMemory     int
 	UUID                 string
 	HotplugVFIOOnRootBus bool
+	VirtiofsdPid         int
 }
 
 // qemu is an Hypervisor interface implementation for the Linux qemu hypervisor.
@@ -459,14 +460,14 @@ func (q *qemu) setupFileBackedMem(knobs *govmmQemu.Knobs, memory *govmmQemu.Memo
 }
 
 // createSandbox is the Hypervisor sandbox creation implementation for govmmQemu.
-func (q *qemu) createSandbox(ctx context.Context, id string, networkNS NetworkNamespace, hypervisorConfig *HypervisorConfig, store *store.VCStore) error {
+func (q *qemu) createSandbox(ctx context.Context, id string, networkNS NetworkNamespace, hypervisorConfig *HypervisorConfig, vcStore *store.VCStore) error {
 	// Save the tracing context
 	q.ctx = ctx
 
 	span, _ := q.trace("createSandbox")
 	defer span.Finish()
 
-	if err := q.setup(id, hypervisorConfig, store); err != nil {
+	if err := q.setup(id, hypervisorConfig, vcStore); err != nil {
 		return err
 	}
 
@@ -558,8 +559,6 @@ func (q *qemu) createSandbox(ctx context.Context, id string, networkNS NetworkNa
 		return err
 	}
 
-	pidFile := q.pidFile()
-
 	qemuConfig := govmmQemu.Config{
 		Name:        fmt.Sprintf("sandbox-%s", q.id),
 		UUID:        q.state.UUID,
@@ -578,7 +577,7 @@ func (q *qemu) createSandbox(ctx context.Context, id string, networkNS NetworkNa
 		VGA:         "none",
 		GlobalParam: "kvm-pit.lost_tick_policy=discard",
 		Bios:        firmwarePath,
-		PidFile:     pidFile,
+		PidFile:     filepath.Join(store.RunVMStoragePath, q.id, "pid"),
 	}
 
 	if ioThread != nil {
@@ -636,6 +635,8 @@ func (q *qemu) setupVirtiofsd(timeout int) (remain int, err error) {
 	defer func() {
 		if err != nil {
 			cmd.Process.Kill()
+		} else {
+			q.state.VirtiofsdPid = cmd.Process.Pid
 		}
 	}()
 
@@ -743,6 +744,9 @@ func (q *qemu) startSandbox(timeout int) error {
 		if err != nil {
 			return err
 		}
+		if err = q.storeState(); err != nil {
+			return err
+		}
 	}
 
 	var strErr string
@@ -1910,24 +1914,26 @@ func (q *qemu) cleanup() error {
 	return nil
 }
 
-func (q *qemu) pidFile() string {
-	return filepath.Join(store.RunVMStoragePath, q.id, "pid")
-}
-
-func (q *qemu) pid() int {
-	data, err := ioutil.ReadFile(q.pidFile())
+func (q *qemu) getPids() []int {
+	data, err := ioutil.ReadFile(q.qemuConfig.PidFile)
 	if err != nil {
 		q.Logger().WithError(err).Error("Could not read qemu pid file")
-		return 0
+		return []int{0}
 	}
 
 	pid, err := strconv.Atoi(strings.Trim(string(data), "\n\t "))
 	if err != nil {
 		q.Logger().WithError(err).Error("Could not convert string to int")
-		return 0
+		return []int{0}
 	}
 
-	return pid
+	var pids []int
+	pids = append(pids, pid)
+	if q.state.VirtiofsdPid != 0 {
+		pids = append(pids, q.state.VirtiofsdPid)
+	}
+
+	return pids
 }
 
 type qemuGrpc struct {
@@ -1992,7 +1998,11 @@ func (q *qemu) storeState() error {
 }
 
 func (q *qemu) save() (s persistapi.HypervisorState) {
-	s.Pid = q.pid()
+	pids := q.getPids()
+	if len(pids) != 0 {
+		s.Pid = pids[0]
+	}
+	s.VirtiofsdPid = q.state.VirtiofsdPid
 	s.Type = string(QemuHypervisor)
 	s.UUID = q.state.UUID
 	s.HotpluggedMemory = q.state.HotpluggedMemory
@@ -2019,6 +2029,7 @@ func (q *qemu) load(s persistapi.HypervisorState) {
 	q.state.UUID = s.UUID
 	q.state.HotpluggedMemory = s.HotpluggedMemory
 	q.state.HotplugVFIOOnRootBus = s.HotplugVFIOOnRootBus
+	q.state.VirtiofsdPid = s.VirtiofsdPid
 
 	for _, bridge := range s.Bridges {
 		q.state.Bridges = append(q.state.Bridges, types.PCIBridge{

virtcontainers/qemu_test.go

@@ -568,3 +568,40 @@ func TestQemuWaitVirtiofsd(t *testing.T) {
 	assert.NotNil(err)
 	assert.True(remain == 0)
 }
+
+func TestQemuGetpids(t *testing.T) {
+	assert := assert.New(t)
+
+	qemuConfig := newQemuConfig()
+	q := &qemu{}
+	pids := q.getPids()
+	assert.NotNil(pids)
+	assert.True(len(pids) == 1)
+	assert.True(pids[0] == 0)
+
+	q = &qemu{
+		config: qemuConfig,
+	}
+	f, err := ioutil.TempFile("", "qemu-test-")
+	assert.Nil(err)
+	tmpfile := f.Name()
+	f.Close()
+	defer os.Remove(tmpfile)
+
+	q.qemuConfig.PidFile = tmpfile
+	pids = q.getPids()
+	assert.True(len(pids) == 1)
+	assert.True(pids[0] == 0)
+
+	err = ioutil.WriteFile(tmpfile, []byte("100"), 0)
+	assert.Nil(err)
+	pids = q.getPids()
+	assert.True(len(pids) == 1)
+	assert.True(pids[0] == 100)
+
+	q.state.VirtiofsdPid = 200
+	pids = q.getPids()
+	assert.True(len(pids) == 2)
+	assert.True(pids[0] == 100)
+	assert.True(pids[1] == 200)
+}

virtcontainers/vm.go

@@ -475,7 +475,7 @@ func (v *VM) ToGrpc(config VMConfig) (*pb.GrpcVM, error) {
 
 func (v *VM) GetVMStatus() *pb.GrpcVMStatus {
 	return &pb.GrpcVMStatus{
-		Pid:    int64(v.hypervisor.pid()),
+		Pid:    int64(getHypervisorPid(v.hypervisor)),
 		Cpu:    v.cpu,
 		Memory: v.memory,
 	}