virtiofs: Allow memory hotplug with virtiofs

Kata with virtio-fs fails to do memory hotplugging. This is caused by the fact that hot plugged memory is always backed by 'memory-backend-ram' while virtio-fs expects it to be backed by file and shared for it to be able to use the system the way it is intended. This chnage allows using file based memory backend for virtio-fs, hugepages or when the user prefers to use a file backed memory Fixes: #1745 Signed-off-by: Ganesh Maharaj Mahalingam <[email protected]>
kata-containers · Jul 17, 2019 · c192343 · c192343
1 parent 0a18fba
commit c192343
Showing 1 changed file with 17 additions and 1 deletion.
diff --git a/virtcontainers/qemu.go b/virtcontainers/qemu.go
@@ -1355,6 +1355,9 @@ func (q *qemu) hotplugMemory(memDev *memoryDevice, op operation) (int, error) {
 
 func (q *qemu) hotplugAddMemory(memDev *memoryDevice) (int, error) {
 	memoryDevices, err := q.qmpMonitorCh.qmp.ExecQueryMemoryDevices(q.qmpMonitorCh.ctx)
+	share := false
+	target := ""
+	memoryBack := "memory-backend-ram"
 	if err != nil {
 		return 0, fmt.Errorf("failed to query memory devices: %v", err)
 	}
@@ -1368,7 +1371,20 @@ func (q *qemu) hotplugAddMemory(memDev *memoryDevice) (int, error) {
 		}
 		memDev.slot = maxSlot + 1
 	}
-	err = q.qmpMonitorCh.qmp.ExecHotplugMemory(q.qmpMonitorCh.ctx, "memory-backend-ram", "mem"+strconv.Itoa(memDev.slot), "", memDev.sizeMB, false)
+	if q.qemuConfig.Knobs.HugePages {
+		// we are setting all the bits that govmm sets when hugepages are enabled.
+		// https://github.com/intel/govmm/blob/master/qemu/qemu.go#L1677
+		target = "/dev/hugepages"
+		memoryBack = "memory-backend-file"
+		share = true
+	} else if q.config.SharedFS == config.VirtioFS || q.config.FileBackedMemRootDir != "" {
+		target = q.qemuConfig.Memory.Path
+		memoryBack = "memory-backend-file"
+	}
+	if q.qemuConfig.Knobs.FileBackedMemShared {
+		share = true
+	}
+	err = q.qmpMonitorCh.qmp.ExecHotplugMemory(q.qmpMonitorCh.ctx, memoryBack, "mem"+strconv.Itoa(memDev.slot), target, memDev.sizeMB, share)
 	if err != nil {
 		q.Logger().WithError(err).Error("hotplug memory")
 		return 0, err