vmm: config: Move TDX to rely on PayloadConfig

Removing the option --tdx to specify that we want to run a TD VM. Rely
on --platform option by adding the "tdx" boolean parameter. This is the
new way for enabling TDX with Cloud Hypervisor.

Along with this change, the way to retrieve the firmware path has been
updated to rely on the recently introduced PayloadConfig structure.

Fixes #4556

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

src/main.rs

@@ -400,15 +400,6 @@ fn create_app<'a>(
             .group("vmm-config"),
     );
 
-    #[cfg(feature = "tdx")]
-    let app = app.arg(
-        Arg::new("tdx")
-            .long("tdx")
-            .help("TDX Support: firmware=<tdvf path>")
-            .takes_value(true)
-            .group("vm-config"),
-    );
-
     app
 }
 
@@ -577,11 +568,6 @@ fn start_vmm(cmd_arguments: ArgMatches) -> Result<Option<String>, Error> {
     let payload_present =
         cmd_arguments.is_present("kernel") || cmd_arguments.is_present("firmware");
 
-    // Can't test for "vm-config" group as some have default values. The kernel (or tdx if enabled)
-    // is the only required option for booting the VM.
-    #[cfg(feature = "tdx")]
-    let payload_present = payload_present || cmd_arguments.is_present("tdx");
-
     if payload_present {
         let vm_params = config::VmParams::from_arg_matches(&cmd_arguments);
         let vm_config = config::VmConfig::parse(vm_params).map_err(Error::ParsingConfig)?;
@@ -744,8 +730,6 @@ mod unit_tests {
             sgx_epc: None,
             numa: None,
             watchdog: false,
-            #[cfg(feature = "tdx")]
-            tdx: None,
             #[cfg(feature = "gdb")]
             gdb: false,
             platform: None,