hypervisor: make getThreadIDs return vcpu to threadid mapping

We need such mapping information to put vcpus in container cpuset properly.

Fixes: #1435

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

virtcontainers/cgroups.go

@@ -227,7 +227,7 @@ func (s *Sandbox) constrainHypervisor(cgroup cgroups.Cgroup) error {
 	if err != nil {
 		return fmt.Errorf("failed to get thread ids from hypervisor: %v", err)
 	}
-	if tids == nil || len(tids.vcpus) == 0 {
+	if len(tids.vcpus) == 0 {
 		// If there's no tid returned from the hypervisor, this is not
 		// a bug. It simply means there is nothing to constrain, hence
 		// let's return without any error from here.

virtcontainers/fc.go

@@ -700,10 +700,10 @@ func (fc *firecracker) resizeVCPUs(reqVCPUs uint32) (currentVCPUs uint32, newVCP
 // Need to see if there's an easy way to ask firecracker for thread ids associated with
 // the vCPUs.  Issue opened to ask for per vCPU thread IDs:
 // https://github.com/firecracker-microvm/firecracker/issues/718
-func (fc *firecracker) getThreadIDs() (*threadIDs, error) {
+func (fc *firecracker) getThreadIDs() (vcpuThreadIDs, error) {
 	//TODO: this may not be exactly supported in Firecracker. Closest is cpu-template as part
 	// of get /machine-config
-	return nil, nil
+	return vcpuThreadIDs{}, nil
 }
 
 func (fc *firecracker) cleanup() error {

virtcontainers/hypervisor.go

@@ -279,8 +279,9 @@ type HypervisorConfig struct {
 	GuestHookPath string
 }
 
-type threadIDs struct {
+// vcpu mapping from vcpu number to thread number
-	vcpus []int
+type vcpuThreadIDs struct {
+	vcpus map[int]int
 }
 
 func (conf *HypervisorConfig) checkTemplateConfig() error {
@@ -597,7 +598,7 @@ type hypervisor interface {
 	disconnect()
 	capabilities() types.Capabilities
 	hypervisorConfig() HypervisorConfig
-	getThreadIDs() (*threadIDs, error)
+	getThreadIDs() (vcpuThreadIDs, error)
 	cleanup() error
 	pid() int
 	fromGrpc(ctx context.Context, hypervisorConfig *HypervisorConfig, store *store.VCStore, j []byte) error

virtcontainers/mock_hypervisor.go

@@ -94,9 +94,9 @@ func (m *mockHypervisor) resizeVCPUs(cpus uint32) (uint32, uint32, error) {
 func (m *mockHypervisor) disconnect() {
 }
 
-func (m *mockHypervisor) getThreadIDs() (*threadIDs, error) {
+func (m *mockHypervisor) getThreadIDs() (vcpuThreadIDs, error) {
-	vcpus := []int{os.Getpid()}
+	vcpus := map[int]int{0: os.Getpid()}
-	return &threadIDs{vcpus}, nil
+	return vcpuThreadIDs{vcpus}, nil
 }
 
 func (m *mockHypervisor) cleanup() error {

virtcontainers/qemu.go

@@ -1509,28 +1509,29 @@ func genericMemoryTopology(memoryMb, hostMemoryMb uint64, slots uint8, memoryOff
 	return memory
 }
 
-func (q *qemu) getThreadIDs() (*threadIDs, error) {
+func (q *qemu) getThreadIDs() (vcpuThreadIDs, error) {
 	span, _ := q.trace("getThreadIDs")
 	defer span.Finish()
 
+	tid := vcpuThreadIDs{}
 	err := q.qmpSetup()
 	if err != nil {
-		return nil, err
+		return tid, err
 	}
 
 	cpuInfos, err := q.qmpMonitorCh.qmp.ExecQueryCpus(q.qmpMonitorCh.ctx)
 	if err != nil {
 		q.Logger().WithError(err).Error("failed to query cpu infos")
-		return nil, err
+		return tid, err
 	}
 
-	var tid threadIDs
+	tid.vcpus = make(map[int]int, len(cpuInfos))
 	for _, i := range cpuInfos {
 		if i.ThreadID > 0 {
-			tid.vcpus = append(tid.vcpus, i.ThreadID)
+			tid.vcpus[i.CPU] = i.ThreadID
 		}
 	}
-	return &tid, nil
+	return tid, nil
 }
 
 func calcHotplugMemMiBSize(mem uint32, memorySectionSizeMB uint32) (uint32, error) {