qemu: Drop support for versions older than 5.0

Kata requires version 5.2 (or 5.1 on ARM) anyway.  Simplify code by
dropping support for older versions.  In any case explicit checks against
version number aren't necessarily reliable for patched qemu versions.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

README.md

@@ -7,8 +7,9 @@
 
 Virtual Machine Manager for Go (govmm) is a suite of packages that
 provide Go APIs for creating and managing virtual machines.  There's
-currently support for only one hypervisor, qemu/kvm, support for which
+currently support for only one hypervisor, qemu/kvm (version 5.0 and
-is provided by the github.com/kata-containers/govmm/qemu package.
+later), support for which is provided by the
+github.com/kata-containers/govmm/qemu package.
 
 The qemu package provides APIs for launching qemu instances and for
 managing those instances via QMP, once launched.  VM instances can

qemu/qmp.go

@@ -719,6 +719,10 @@ func QMPStart(ctx context.Context, socket string, cfg QMPConfig, disconnectedCh
 		}
 	}
 
+	if q.version.Major < 5 {
+		return nil, nil, fmt.Errorf("govmm requires qemu version 5.0 or later, this is qemu (%d.%d)", q.version.Major, q.version.Minor)
+	}
+
 	return q, q.version, nil
 }
 
@@ -780,15 +784,8 @@ func (q *QMP) blockdevAddBaseArgs(device, blockdevID string, ro bool) (map[strin
 		},
 	}
 
-	if q.version.Major > 2 || (q.version.Major == 2 && q.version.Minor >= 8) {
+	blockdevArgs["node-name"] = blockdevID
-		blockdevArgs["node-name"] = blockdevID
+	args = blockdevArgs
-		args = blockdevArgs
-	} else {
-		blockdevArgs["id"] = blockdevID
-		args = map[string]interface{}{
-			"options": blockdevArgs,
-		}
-	}
 
 	return args, blockdevArgs
 }
@@ -813,11 +810,6 @@ func (q *QMP) ExecuteBlockdevAdd(ctx context.Context, device, blockdevID string,
 func (q *QMP) ExecuteBlockdevAddWithCache(ctx context.Context, device, blockdevID string, direct, noFlush, ro bool) error {
 	args, blockdevArgs := q.blockdevAddBaseArgs(device, blockdevID, ro)
 
-	if q.version.Major < 2 || (q.version.Major == 2 && q.version.Minor < 9) {
-		return fmt.Errorf("versions of qemu (%d.%d) older than 2.9 do not support set cache-related options for block devices",
-			q.version.Major, q.version.Minor)
-	}
-
 	blockdevArgs["cache"] = map[string]interface{}{
 		"direct":   direct,
 		"no-flush": noFlush,
@@ -850,7 +842,7 @@ func (q *QMP) ExecuteDeviceAdd(ctx context.Context, blockdevID, devID, driver, b
 		args["bus"] = bus
 	}
 
-	if shared && (q.version.Major > 2 || (q.version.Major == 2 && q.version.Minor >= 10)) {
+	if shared {
 		args["share-rw"] = "on"
 	}
 	if transport.isVirtioPCI(nil) {
@@ -904,32 +896,22 @@ func (q *QMP) ExecuteSCSIDeviceAdd(ctx context.Context, blockdevID, devID, drive
 	if lun >= 0 {
 		args["lun"] = lun
 	}
-	if shared && (q.version.Major > 2 || (q.version.Major == 2 && q.version.Minor >= 10)) {
+	if shared {
 		args["share-rw"] = "on"
 	}
 
 	return q.executeCommand(ctx, "device_add", args, nil)
 }
 
-// ExecuteBlockdevDel deletes a block device by sending a x-blockdev-del command
+// ExecuteBlockdevDel deletes a block device by sending blockdev-del
-// for qemu versions < 2.9. It sends the updated blockdev-del command for qemu>=2.9.
+// command.  blockdevID is the id of the block device to be deleted.
-// blockdevID is the id of the block device to be deleted.  Typically, this will
+// Typically, this will match the id passed to ExecuteBlockdevAdd.  It
-// match the id passed to ExecuteBlockdevAdd.  It must be a valid QMP id.
+// must be a valid QMP id.
 func (q *QMP) ExecuteBlockdevDel(ctx context.Context, blockdevID string) error {
 	args := map[string]interface{}{}
 
-	if q.version.Major > 2 || (q.version.Major == 2 && q.version.Minor >= 9) {
+	args["node-name"] = blockdevID
-		args["node-name"] = blockdevID
+	return q.executeCommand(ctx, "blockdev-del", args, nil)
-		return q.executeCommand(ctx, "blockdev-del", args, nil)
-	}
-
-	if q.version.Major == 2 && q.version.Minor == 8 {
-		args["node-name"] = blockdevID
-	} else {
-		args["id"] = blockdevID
-	}
-
-	return q.executeCommand(ctx, "x-blockdev-del", args, nil)
 }
 
 // ExecuteChardevDel deletes a char device by sending a chardev-remove command.
@@ -1104,7 +1086,7 @@ func (q *QMP) ExecutePCIDeviceAdd(ctx context.Context, blockdevID, devID, driver
 	if bus != "" {
 		args["bus"] = bus
 	}
-	if shared && (q.version.Major > 2 || (q.version.Major == 2 && q.version.Minor >= 10)) {
+	if shared {
 		args["share-rw"] = "on"
 	}
 	if queues > 0 {
@@ -1240,10 +1222,7 @@ func isThreadIDSupported(driver string) bool {
 
 // isDieIDSupported returns if the cpu driver and the qemu version support the die id option
 func (q *QMP) isDieIDSupported(driver string) bool {
-	if (q.version.Major > 4 || (q.version.Major == 4 && q.version.Minor >= 1)) && driver == "host-x86_64-cpu" {
+	return driver == "host-x86_64-cpu"
-		return true
-	}
-	return false
 }
 
 // ExecuteCPUDeviceAdd adds a CPU to a QEMU instance using the device_add command.
@@ -1454,11 +1433,9 @@ func (q *QMP) ExecuteNVDIMMDeviceAdd(ctx context.Context, id, mempath string, si
 		},
 	}
 
-	if q.version.Major > 4 || (q.version.Major == 4 && q.version.Minor >= 1) {
+	if pmem != nil {
-		if pmem != nil {
+		props := args["props"].(map[string]interface{})
-			props := args["props"].(map[string]interface{})
+		props["pmem"] = *pmem
-			props["pmem"] = *pmem
-		}
 	}
 
 	err := q.executeCommand(ctx, "object-add", args, nil)

qemu/qmp_test.go

@@ -1125,10 +1125,6 @@ func TestQMPCPUDeviceAdd(t *testing.T) {
 	dieID := "0"
 	coreID := "1"
 	threadID := "0"
-	version := &QMPVersion{
-		Major: 4,
-		Minor: 1,
-	}
 	for _, d := range drivers {
 		connectedCh := make(chan *QMPVersion)
 		disconnectedCh := make(chan struct{})
@@ -1137,7 +1133,6 @@ func TestQMPCPUDeviceAdd(t *testing.T) {
 		cfg := QMPConfig{Logger: qmpTestLogger{}}
 		q := startQMPLoop(buf, cfg, connectedCh, disconnectedCh)
 		checkVersion(t, connectedCh)
-		q.version = version
 		err := q.ExecuteCPUDeviceAdd(context.Background(), d, cpuID, socketID, dieID, coreID, threadID, "")
 		if err != nil {
 			t.Fatalf("Unexpected error %v", err)
@@ -1634,10 +1629,6 @@ func TestExecuteNVDIMMDeviceAdd(t *testing.T) {
 	cfg := QMPConfig{Logger: qmpTestLogger{}}
 	q := startQMPLoop(buf, cfg, connectedCh, disconnectedCh)
 	checkVersion(t, connectedCh)
-	q.version = &QMPVersion{
-		Major: 4,
-		Minor: 1,
-	}
 	pmem := true
 	err := q.ExecuteNVDIMMDeviceAdd(context.Background(), "nvdimm0", "/dev/rbd0", 1024, &pmem)
 	if err != nil {