x86/spec-ctrl: command line handling adjustments

For one, "no-xen" should not imply "no-eager-fpu", as "eager FPU" mode
is to guard guests, not Xen itself, which is also expressed so by
print_details().

And then opt_ssbd, despite being off by default, should also be cleared
by the "no" and "no-xen" sub-options.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: ac3f9a7214
master date: 2018-07-10 12:22:31 +0200

xen/arch/x86/spec_ctrl.c

@@ -108,6 +108,8 @@ static int __init parse_spec_ctrl(char *s)
             opt_msr_sc_pv = 0;
             opt_msr_sc_hvm = 0;
 
+            opt_eager_fpu = 0;
+
         disable_common:
             opt_rsb_pv = 0;
             opt_rsb_hvm = 0;
@@ -115,7 +117,7 @@ static int __init parse_spec_ctrl(char *s)
             opt_thunk = THUNK_JMP;
             opt_ibrs = 0;
             opt_ibpb = 0;
-            opt_eager_fpu = 0;
+            opt_ssbd = 0;
         }
         else if ( val > 0 )
             rc = -EINVAL;