virtio-mmio: Add support for virtio-mmio blk devices

Add support for discovery of rootfs passed in via virtio-mmio.
The discovery is done based on predicted device name.

Signed-off-by: Manohar Castelino <manohar.r.castelino@intel.com>

Author: mcastelino

device.go

@@ -26,6 +26,7 @@ import (
 const (
 	driver9pType        = "9p"
 	driverBlkType       = "blk"
+	driverMmioBlkType   = "mmioblk"
 	driverSCSIType      = "scsi"
 	driverNvdimmType    = "nvdimm"
 	driverEphemeralType = "ephemeral"
@@ -59,9 +60,10 @@ var (
 type deviceHandler func(device pb.Device, spec *pb.Spec, s *sandbox) error
 
 var deviceHandlerList = map[string]deviceHandler{
-	driverBlkType:    virtioBlkDeviceHandler,
-	driverSCSIType:   virtioSCSIDeviceHandler,
-	driverNvdimmType: nvdimmDeviceHandler,
+	driverMmioBlkType: virtioMmioBlkDeviceHandler,
+	driverBlkType:     virtioBlkDeviceHandler,
+	driverSCSIType:    virtioSCSIDeviceHandler,
+	driverNvdimmType:  nvdimmDeviceHandler,
 }
 
 func rescanPciBus() error {
@@ -168,6 +170,16 @@ func getPCIDeviceName(s *sandbox, pciID string) (string, error) {
 	return filepath.Join(systemDevPath, devName), nil
 }
 
+// device.Id should be the predicted device name (vda, vdb, ...)
+// device.VmPath already provides a way to send it in
+func virtioMmioBlkDeviceHandler(device pb.Device, spec *pb.Spec, s *sandbox) error {
+	if device.VmPath == "" {
+		return fmt.Errorf("Invalid path for virtioMmioBlkDevice")
+	}
+
+	return updateSpecDeviceList(device, spec)
+}
+
 // device.Id should be the PCI address in the format  "bridgeAddr/deviceAddr".
 // Here, bridgeAddr is the address at which the brige is attached on the root bus,
 // while deviceAddr is the address at which the device is attached on the bridge.

mount.go

@@ -192,6 +192,7 @@ type storageHandler func(storage pb.Storage, s *sandbox) (string, error)
 var storageHandlerList = map[string]storageHandler{
 	driver9pType:        virtio9pStorageHandler,
 	driverBlkType:       virtioBlkStorageHandler,
+	driverMmioBlkType:   virtioMmioBlkStorageHandler,
 	driverSCSIType:      virtioSCSIStorageHandler,
 	driverEphemeralType: ephemeralStorageHandler,
 }
@@ -216,6 +217,12 @@ func virtio9pStorageHandler(storage pb.Storage, s *sandbox) (string, error) {
 	return commonStorageHandler(storage)
 }
 
+// virtioMmioBlkStorageHandler handles the storage for mmio blk driver.
+func virtioMmioBlkStorageHandler(storage pb.Storage, s *sandbox) (string, error) {
+	//The source path is VmPath
+	return commonStorageHandler(storage)
+}
+
 // virtioBlkStorageHandler handles the storage for blk driver.
 func virtioBlkStorageHandler(storage pb.Storage, s *sandbox) (string, error) {
 	// Get the device node path based on the PCI address provided