virtcontainers: Add support for updating virtio-blk based container rootfs

Thist patch adds the following,
1. ACRN only supports virtio-blk and so the rootfs for the VM
   sits at /dev/vda. So to get the container rootfs increment the
   globalIndex by 1.
2. ACRN doesn't hot-plug container rootfs (but uses blkrescan) to
   update the container rootfs. So the agent can be provided the virtpath
   rather than the PCIaddr avoiding unneccessary rescaning to find the
   virthpath.

v1->v2:
Removed the workaround of incrementing index for
virtio-blk device and addressed it acrn.

Fixes: #1778

Signed-off-by: Vijay Dhanraj <vijay.dhanraj@intel.com>

virtcontainers/device/api/interface.go

@@ -7,10 +7,9 @@
 package api
 
 import (
-	"github.com/sirupsen/logrus"
-
 	"github.com/kata-containers/runtime/virtcontainers/device/config"
 	persistapi "github.com/kata-containers/runtime/virtcontainers/persist/api"
+	"github.com/sirupsen/logrus"
 )
 
 var devLogger = logrus.WithField("subsystem", "device")
@@ -36,6 +35,7 @@ type DeviceReceiver interface {
 	// this is only for virtio-blk and virtio-scsi support
 	GetAndSetSandboxBlockIndex() (int, error)
 	DecrementSandboxBlockIndex() error
+	GetHypervisorType() string
 
 	// this is for appending device to hypervisor boot params
 	AppendDevice(Device) error

virtcontainers/device/api/mockDeviceReceiver.go

@@ -36,3 +36,8 @@ func (mockDC *MockDeviceReceiver) DecrementSandboxBlockIndex() error {
 func (mockDC *MockDeviceReceiver) AppendDevice(Device) error {
 	return nil
 }
+
+// GetHypervisorType is used for getting Hypervisor name currently used.
+func (mockDC *MockDeviceReceiver) GetHypervisorType() string {
+	return ""
+}

virtcontainers/kata_agent.go

@@ -19,6 +19,7 @@ import (
 	"syscall"
 	"time"
 
+	"github.com/gogo/protobuf/proto"
 	aTypes "github.com/kata-containers/agent/pkg/types"
 	kataclient "github.com/kata-containers/agent/protocols/client"
 	"github.com/kata-containers/agent/protocols/grpc"
@@ -30,10 +31,8 @@ import (
 	"github.com/kata-containers/runtime/virtcontainers/store"
 	"github.com/kata-containers/runtime/virtcontainers/types"
 	"github.com/kata-containers/runtime/virtcontainers/utils"
-	opentracing "github.com/opentracing/opentracing-go"
-
-	"github.com/gogo/protobuf/proto"
 	"github.com/opencontainers/runtime-spec/specs-go"
+	opentracing "github.com/opentracing/opentracing-go"
 	"github.com/sirupsen/logrus"
 	"github.com/vishvananda/netlink"
 	"golang.org/x/net/context"
@@ -1084,7 +1083,12 @@ func (k *kataAgent) buildContainerRootfs(sandbox *Sandbox, c *Container, rootPat
 			rootfs.Source = blockDrive.VirtPath
 		} else if sandbox.config.HypervisorConfig.BlockDeviceDriver == config.VirtioBlock {
 			rootfs.Driver = kataBlkDevType
+			if blockDrive.PCIAddr == "" {
+				rootfs.Source = blockDrive.VirtPath
+			} else {
 				rootfs.Source = blockDrive.PCIAddr
+			}
+
 		} else {
 			rootfs.Driver = kataSCSIDevType
 			rootfs.Source = blockDrive.SCSIAddr

virtcontainers/sandbox.go

@@ -15,12 +15,6 @@ import (
 	"syscall"
 
 	"github.com/containernetworking/plugins/pkg/ns"
-	specs "github.com/opencontainers/runtime-spec/specs-go"
-	opentracing "github.com/opentracing/opentracing-go"
-	"github.com/pkg/errors"
-	"github.com/sirupsen/logrus"
-	"github.com/vishvananda/netlink"
-
 	"github.com/kata-containers/agent/protocols/grpc"
 	"github.com/kata-containers/runtime/virtcontainers/device/api"
 	"github.com/kata-containers/runtime/virtcontainers/device/config"
@@ -34,6 +28,11 @@ import (
 	"github.com/kata-containers/runtime/virtcontainers/store"
 	"github.com/kata-containers/runtime/virtcontainers/types"
 	"github.com/kata-containers/runtime/virtcontainers/utils"
+	specs "github.com/opencontainers/runtime-spec/specs-go"
+	opentracing "github.com/opentracing/opentracing-go"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+	"github.com/vishvananda/netlink"
 )
 
 const (
@@ -1842,3 +1841,9 @@ func (s *Sandbox) calculateSandboxCPUs() uint32 {
 	}
 	return utils.CalculateVCpusFromMilliCpus(mCPU)
 }
+
+// GetHypervisorType is used for getting Hypervisor name currently used.
+// Sandbox implement DeviceReceiver interface from device/api/interface.go
+func (s *Sandbox) GetHypervisorType() string {
+	return string(s.config.HypervisorType)
+}