Refactor code to support multiple virtio transports at runtime

Currently, virtio transports for each device are determined with
architecture dependent build time conditionals. This isn't the ideal
solution, as virtio transports aren't exactly tied to the host's
architecture.

For example, aarch64 VMs do support both PCI and MMIO devices, and
after the recent introduction of the microvm machine type, that's also
the case for x86_64.

This patch extends each device that supports multiple transports with
a VirtioTransport field, so users of the library can manually specify
a transport for each device. To avoid breaking the compatibility, if
VirtioTransport is empty a behavior equivalent to the legacy one is
achieved by checking runtime.GOARCH and Config.Machine.Type.

Keeping support for isVirtioPCI/isVirtioCCW in qmp.go is a bit
tricky. Eventually, the hot-plug API should be extended so callers
must manually specify the transport for the device.

Signed-off-by: Sergio Lopez <slp@redhat.com>

qemu/qemu_test.go

@@ -143,7 +143,7 @@ func TestAppendDeviceFS(t *testing.T) {
 		ROMFile:       "efi-virtio.rom",
 	}
 
-	if isVirtioCCW[fsdev.Driver] {
+	if fsdev.Transport.isVirtioCCW(nil) {
 		fsdev.DevNo = DevNo
 	}
 
@@ -164,7 +164,7 @@ func TestAppendDeviceNetwork(t *testing.T) {
 		ROMFile:       "efi-virtio.rom",
 	}
 
-	if isVirtioCCW[netdev.Driver] {
+	if netdev.Transport.isVirtioCCW(nil) {
 		netdev.DevNo = DevNo
 	}
 
@@ -195,7 +195,7 @@ func TestAppendDeviceNetworkMq(t *testing.T) {
 		DisableModern: true,
 		ROMFile:       "efi-virtio.rom",
 	}
-	if isVirtioCCW[netdev.Driver] {
+	if netdev.Transport.isVirtioCCW(nil) {
 		netdev.DevNo = DevNo
 	}
 
@@ -219,7 +219,7 @@ func TestAppendDeviceNetworkPCI(t *testing.T) {
 		ROMFile:       romfile,
 	}
 
-	if !isVirtioPCI[netdev.Driver] {
+	if !netdev.Transport.isVirtioPCI(nil) {
 		t.Skip("Test valid only for PCI devices")
 	}
 
@@ -253,7 +253,7 @@ func TestAppendDeviceNetworkPCIMq(t *testing.T) {
 		ROMFile:       romfile,
 	}
 
-	if !isVirtioPCI[netdev.Driver] {
+	if !netdev.Transport.isVirtioPCI(nil) {
 		t.Skip("Test valid only for PCI devices")
 	}
 
@@ -267,7 +267,7 @@ func TestAppendDeviceSerial(t *testing.T) {
 		DisableModern: true,
 		ROMFile:       romfile,
 	}
-	if isVirtioCCW[sdev.Driver] {
+	if sdev.Transport.isVirtioCCW(nil) {
 		sdev.DevNo = DevNo
 	}
 
@@ -285,7 +285,7 @@ func TestAppendDeviceSerialPort(t *testing.T) {
 		Path:     "/tmp/char.sock",
 		Name:     "channel.0",
 	}
-	if isVirtioCCW[chardev.Driver] {
+	if chardev.Transport.isVirtioCCW(nil) {
 		chardev.DevNo = DevNo
 	}
 	testAppend(chardev, deviceSerialPortString, t)
@@ -304,7 +304,7 @@ func TestAppendDeviceBlock(t *testing.T) {
 		DisableModern: true,
 		ROMFile:       romfile,
 	}
-	if isVirtioCCW[blkdev.Driver] {
+	if blkdev.Transport.isVirtioCCW(nil) {
 		blkdev.DevNo = DevNo
 	}
 	testAppend(blkdev, deviceBlockString, t)
@@ -318,7 +318,7 @@ func TestAppendDeviceVFIO(t *testing.T) {
 		DeviceID: "0x5678",
 	}
 
-	if isVirtioCCW[Vfio] {
+	if vfioDevice.Transport.isVirtioCCW(nil) {
 		vfioDevice.DevNo = DevNo
 	}
 
@@ -334,7 +334,7 @@ func TestAppendVSOCK(t *testing.T) {
 		ROMFile:       romfile,
 	}
 
-	if isVirtioCCW[VHostVSock] {
+	if vsockDevice.Transport.isVirtioCCW(nil) {
 		vsockDevice.DevNo = DevNo
 	}
 
@@ -368,16 +368,19 @@ func TestVSOCKValid(t *testing.T) {
 
 func TestAppendVirtioRng(t *testing.T) {
 	var objectString = "-object rng-random,id=rng0"
-	var deviceString = "-device " + string(VirtioRng) + ",rng=rng0"
-	if romfile != "" {
-		deviceString = deviceString + ",romfile=efi-virtio.rom"
-	}
+	var deviceString = "-device " + string(VirtioRng)
+
 	rngDevice := RngDevice{
 		ID:      "rng0",
 		ROMFile: romfile,
 	}
 
-	if isVirtioCCW[VirtioRng] {
+	deviceString += "-" + string(rngDevice.Transport.getName(nil)) + ",rng=rng0"
+	if romfile != "" {
+		deviceString = deviceString + ",romfile=efi-virtio.rom"
+	}
+
+	if rngDevice.Transport.isVirtioCCW(nil) {
 		rngDevice.DevNo = DevNo
 		deviceString += ",devno=" + rngDevice.DevNo
 	}
@@ -438,7 +441,7 @@ func TestAppendDeviceSCSIController(t *testing.T) {
 		ROMFile: romfile,
 	}
 
-	if isVirtioCCW[VirtioScsi] {
+	if scsiCon.Transport.isVirtioCCW(nil) {
 		scsiCon.DevNo = DevNo
 	}
 
@@ -521,7 +524,7 @@ func TestAppendKnobsAllFalse(t *testing.T) {
 }
 
 func TestAppendMemoryHugePages(t *testing.T) {
-	if !isDimmSupported() {
+	if !isDimmSupported(nil) {
 		t.Skip("Dimm not supported")
 	}
 
@@ -549,7 +552,7 @@ func TestAppendMemoryHugePages(t *testing.T) {
 }
 
 func TestAppendMemoryMemPrealloc(t *testing.T) {
-	if !isDimmSupported() {
+	if !isDimmSupported(nil) {
 		t.Skip("Dimm not supported")
 	}
 
@@ -575,7 +578,7 @@ func TestAppendMemoryMemPrealloc(t *testing.T) {
 }
 
 func TestAppendMemoryMemShared(t *testing.T) {
-	if !isDimmSupported() {
+	if !isDimmSupported(nil) {
 		t.Skip("Dimm not supported")
 	}
 
@@ -601,7 +604,7 @@ func TestAppendMemoryMemShared(t *testing.T) {
 }
 
 func TestAppendMemoryFileBackedMem(t *testing.T) {
-	if !isDimmSupported() {
+	if !isDimmSupported(nil) {
 		t.Skip("Dimm not supported")
 	}
 
@@ -627,7 +630,7 @@ func TestAppendMemoryFileBackedMem(t *testing.T) {
 }
 
 func TestAppendMemoryFileBackedMemPrealloc(t *testing.T) {
-	if !isDimmSupported() {
+	if !isDimmSupported(nil) {
 		t.Skip("Dimm not supported")
 	}