Re: [Xen-devel] [PATCH v3 8/8] RFC: Sketch constructors, DomainCreateNew

[George Dunlap <george.dunlap@citrix.com>]

On 1/17/20 3:57 PM, George Dunlap wrote:
> This is a sketch of functionality suitable for creating a basic
> domain, with a disk and a vif.  DomainConfig, DeviceDisk, and
> DeviceNic types are all created using constructor functions, which
> initialize them with libxl's defaults.
> 
> DomainCreateNew takes the config and calls without any updates.
> 
> Obviously some of these will need to be changed it we switch to
> passing references to .toC() rather than passing back by value.
> 
> The main purpose of this is to allow testing of creating a hard-coded
> domain.
> 
> Creating a domain would look like this:
> 
> 	// type = "pv"
> 	dconf, err := xl.NewDomainConfig(xl.DomainTypePv)
> 	if err != nil {
> 		fmt.Printf("NewDomainConfig: %v\n", err)
> 		return
> 	}
> 	dconf.CInfo.Type = xl.DomainTypePv
> 	// name = "c6-01"
> 	dconf.CInfo.Name = "c6-01"
> 	// vcpus=4
> 	dconf.BInfo.MaxVcpus = 4
> 	// memory = "2048"
> 	dconf.BInfo.MaxMemkb = 2048 * 1024
> 	dconf.BInfo.TargetMemkb = 2048 * 1024
> 	// on_crash = 'destroy'
> 	dconf.OnCrash = xl.ActionOnShutdownDestroy
> 	// bootloader = "pygrub"
> 	dconf.BInfo.Bootloader = "pygrub"
> 	// disk = [ 'vdev=hda,format=raw,target=/images/c6-01.raw']
> 	{
> 		disk, err := xl.NewDeviceDisk()
> 		if err != nil {
> 			fmt.Printf("NewDeviceDisk: %v\n", err)
> 			return
> 		}
> 		disk.Vdev = "hda"
> 		//disk.DiskBackend = xl.DiskBackendPhy
> 		disk.Format = xl.DiskFormatRaw
> 		disk.Readwrite = 1
> 		disk.PdevPath = "/images/c6-01.raw"
> 		dconf.Disks = append(dconf.Disks, *disk)
> 	}
> 	// vif = [ 'mac=5a:5b:d6:f1:d6:b4' ]
> 	{
> 		vif, err := xl.NewDeviceNic()
> 		if err != nil {
> 			fmt.Printf("NewDeviceNic: %v\n", err)
> 			return
> 		}
> 		vif.Mac = xl.Mac{ 0x5a, 0x5b, 0xd6, 0x31, 0xd6, 0xb4 }
> 		dconf.Nics = append(dconf.Nics, *vif)
> 	}
> 	// serial='pty' # HVM only
> 
> 	did, err := ctx.DomainCreateNew(dconf)
> 
> 	if err != nil {
> 		fmt.Printf("Creating domain: %v\n", err)
> 		return
> 	}
> 
> 	fmt.Printf("Domain %s(%d) created successfully", dconf.CInfo.Name, did)
> 
> 
> Signed-off-by: George Dunlap <george.dunlap@citrix.com>
> ---
> CC: Nick Rosbrook <rosbrookn@ainfosec.com>
> ---
>  tools/golang/xenlight/xenlight.go | 66 +++++++++++++++++++++++++++++++
>  1 file changed, 66 insertions(+)
> 
> diff --git a/tools/golang/xenlight/xenlight.go b/tools/golang/xenlight/xenlight.go
> index c462e4bb42..5a21a2b9b8 100644
> --- a/tools/golang/xenlight/xenlight.go
> +++ b/tools/golang/xenlight/xenlight.go
> @@ -1113,3 +1113,69 @@ func (Ctx *Context) PrimaryConsoleGetTty(domid uint32) (path string, err error)
>  	path = C.GoString(cpath)
>  	return
>  }
> +
> +func NewDomainConfig(t DomainType) (*DomainConfig, error) {
> +	var cconfig C.libxl_domain_config
> +
> +	C.libxl_domain_config_init(&cconfig)
> +	C.libxl_domain_build_info_init_type(&cconfig.b_info, C.libxl_domain_type(t))
> +
> +	gconfig := &DomainConfig{}
> +	err := gconfig.fromC(&cconfig)
> +	if err != nil {
> +		return nil, err
> +	}
> +
> +	return gconfig, nil
> +}
> +
> +func NewDeviceDisk() (*DeviceDisk, error) {
> +	var ctype C.libxl_device_disk
> +
> +	C.libxl_device_disk_init(&ctype)
> +
> +	gtype := &DeviceDisk{}
> +	err := gtype.fromC(&ctype)
> +
> +	if err != nil {
> +		return nil, err
> +	}
> +
> +	return gtype, nil
> +}
> +
> +func NewDeviceNic() (*DeviceNic, error) {
> +	var ctype C.libxl_device_nic
> +
> +	C.libxl_device_nic_init(&ctype)
> +
> +	gtype := &DeviceNic{}
> +	err := gtype.fromC(&ctype)
> +
> +	if err != nil {
> +		return nil, err
> +	}
> +
> +	return gtype, nil
> +}
> +
> +// int libxl_domain_create_new(libxl_ctx *ctx, libxl_domain_config *d_config,
> +//                             uint32_t *domid,
> +//                             const libxl_asyncop_how *ao_how,
> +//                             const libxl_asyncprogress_how *aop_console_how)
> +func (Ctx *Context) DomainCreateNew(config *DomainConfig) (Domid, error) {
> +	var cdomid C.uint32_t
> +	var cconfig C.libxl_domain_config
> +	err := config.toC(&cconfig)
> +	if err != nil {
> +		return Domid(0), fmt.Errorf("converting domain config to C: %v", err)
> +	}
> +	defer C.libxl_domain_config_dispose(&cconfig)
> +
> +	ret := C.libxl_domain_create_new(Ctx.ctx, &cconfig, &cdomid, nil, nil)
> +	if ret != 0 {
> +		return Domid(0), Error(ret)
> +	}
> +
> +	return Domid(cdomid), nil
> +}

An alternate way to do this would be something like this:

---
func NewDomainConfig(t DomainType, populate func(*DomainConfig))
*DomainConfig {
	var ctype C.libxl_domain_config

	C.libxl_domain_config_init(&ctype)
	C.libxl_domain_build_info_init_type(&ctype.b_info, C.libxl_domain_type(t))

	gtype := &DomainConfig{}
	err := gtype.fromC(&ctype)
	if err != nil {
		panic("internal error: Can't convert empty DomainConfig")
	}

	if populate != nil {
		populate(gtype)
	}

	return gtype
}

func NewDeviceDisk(populate func(*DeviceDisk)) *DeviceDisk {
	var ctype C.libxl_device_disk

	C.libxl_device_disk_init(&ctype)

	gtype := &DeviceDisk{}
	err := gtype.fromC(&ctype)

	if err != nil {
		panic("internal error: Can't convert empty DeviceDisk")
	}

	if populate != nil {
		populate(gtype)
	}

	return gtype
}

func NewDeviceNic(populate func(*DeviceNic)) *DeviceNic {
	var ctype C.libxl_device_nic

	C.libxl_device_nic_init(&ctype)

	gtype := &DeviceNic{}
	err := gtype.fromC(&ctype)

	if err != nil {
		panic("internal error: Can't convert empty DeviceNic")
	}

	if populate != nil {
		populate(gtype)
	}

	return gtype
}
---

And then code to populate a domain config might look like this:

	dconf := xl.NewDomainConfig(xl.DomainTypePv, func(dconf *xl.DomainConfig) {
		dconf.CInfo.Type = xl.DomainTypePv
		// name = "c6-01"
		dconf.CInfo.Name = "c6-01"
		// vcpus=4
		dconf.BInfo.MaxVcpus = 4
		// memory = "2048"
		dconf.BInfo.MaxMemkb = 2048 * 1024
		dconf.BInfo.TargetMemkb = 2048 * 1024
		// on_crash = 'destroy'
		dconf.OnCrash = xl.ActionOnShutdownDestroy
		// bootloader = "pygrub"
		dconf.BInfo.Bootloader = "pygrub"
	})

	dconf.Disks = []xl.DeviceDisk{*xl.NewDeviceDisk(func(disk *xl.DeviceDisk) {
		disk.Vdev = "hda"
		//disk.DiskBackend = xl.DiskBackendPhy
		disk.Format = xl.DiskFormatRaw
		disk.Readwrite = 1
		disk.PdevPath = "/images/c6-01.raw"
		dconf.Disks = append(dconf.Disks, *disk)
	})}

	dconf.Nics = []xl.DeviceNic{*xl.NewDeviceNic(func(vif *xl.DeviceNic) {
		vif.Mac = xl.Mac{0x5a, 0x5b, 0xd6, 0x31, 0xd6, 0xb4}
	})}


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