runtime: Add IOMMUFD Object Creation for QEMU QMP Commands

The QMP commands sent to QEMU did not properly set up
IOMMUFD objects in the codepath that handles VFIO device
hot-plugging. This is mainly relevant in the Kubernetes
use-case where the VFIO devices are not available when
QEMU is first launched.

Signed-off-by: LandonTClipp <11232769+LandonTClipp@users.noreply.github.com>

.gitignore

@@ -18,3 +18,4 @@ src/tools/log-parser/kata-log-parser
 tools/packaging/static-build/agent/install_libseccomp.sh
 .envrc
 .direnv
+**/.DS_Store

src/runtime/pkg/device/config/config.go

@@ -15,6 +15,7 @@ import (
 
 	"github.com/container-orchestrated-devices/container-device-interface/pkg/cdi"
 	"github.com/go-ini/ini"
+	"github.com/kata-containers/kata-containers/src/runtime/pkg/device/drivers"
 	vcTypes "github.com/kata-containers/kata-containers/src/runtime/virtcontainers/types"
 	"github.com/opencontainers/runtime-spec/specs-go"
 	"golang.org/x/sys/unix"
@@ -431,6 +432,16 @@ type VFIODev struct {
 	HostPath string
 }
 
+// IOMMUFDID returns the IOMMUFD ID if the VFIO device is backed by IOMMUFD
+// otherwise returns an empty string.
+func (t VFIODev) IOMMUFDID() string {
+	if !strings.HasPrefix(t.DevfsDev, drivers.IommufdDevPath) {
+		return ""
+	}
+	basename := filepath.Base(t.DevfsDev)
+	return strings.TrimPrefix(basename, "vfio")
+}
+
 // RNGDev represents a random number generator device
 type RNGDev struct {
 	// ID is used to identify the device in the hypervisor options.

src/runtime/pkg/govmm/qemu/qmp.go

@@ -1160,7 +1160,8 @@ func (q *QMP) ExecutePCIVhostUserDevAdd(ctx context.Context, driver, devID, char
 // devID is the id of the device to add. Must be valid QMP identifier.
 // bdf is the PCI bus-device-function of the pci device.
 // bus is optional. When hot plugging a PCIe device, the bus can be the ID of the pcie-root-port.
-func (q *QMP) ExecuteVFIODeviceAdd(ctx context.Context, devID, bdf, bus, romfile string) error {
+// iommufdID is the ID of the iommufd object to be created for this device. If empty, no iommufd object will be created.
+func (q *QMP) ExecuteVFIODeviceAdd(ctx context.Context, devID, bdf, bus, romfile string, iommufdID string) error {
 	var driver string
 	var transport VirtioTransport
 
@@ -1179,6 +1180,16 @@ func (q *QMP) ExecuteVFIODeviceAdd(ctx context.Context, devID, bdf, bus, romfile
 	if bus != "" {
 		args["bus"] = bus
 	}
+	if iommufdID != "" {
+		objectAddArgs := map[string]interface{}{
+			"qom-type": "iommufd",
+			"id":       iommufdID,
+		}
+		if err := q.executeCommand(ctx, "object-add", objectAddArgs, nil); err != nil {
+			return err
+		}
+		args["iommufd"] = iommufdID
+	}
 	return q.executeCommand(ctx, "device_add", args, nil)
 }
 

src/runtime/virtcontainers/qemu.go

@@ -1876,7 +1876,7 @@ func (q *qemu) executePCIVFIODeviceAdd(device *config.VFIODev, addr string, brid
 func (q *qemu) executeVFIODeviceAdd(device *config.VFIODev) error {
 	switch device.Type {
 	case config.VFIOPCIDeviceNormalType:
-		return q.qmpMonitorCh.qmp.ExecuteVFIODeviceAdd(q.qmpMonitorCh.ctx, device.ID, device.BDF, device.Bus, romFile)
+		return q.qmpMonitorCh.qmp.ExecuteVFIODeviceAdd(q.qmpMonitorCh.ctx, device.ID, device.BDF, device.Bus, romFile, device.IOMMUFDID())
 	case config.VFIOPCIDeviceMediatedType:
 		return q.qmpMonitorCh.qmp.ExecutePCIVFIOMediatedDeviceAdd(q.qmpMonitorCh.ctx, device.ID, device.SysfsDev, "", device.Bus, romFile)
 	case config.VFIOAPDeviceMediatedType: