x86: fix "xpti=" and "pv-l1tf=" yet again

While commit 2a3b34ec47 ("x86/spec-ctrl: Yet more fixes for xpti=
parsing") indeed fixed "xpti=dom0", it broke "xpti=no-dom0", in that
this then became equivalent to "xpti=no". In particular, the presence
of "xpti=" alone on the command line means nothing as to which default
is to be overridden; "xpti=no-dom0", for example, ought to have no
effect for DomU-s, as this is distinct from both "xpti=no-dom0,domu"
and "xpti=no-dom0,no-domu".

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 8743d2dea5
master date: 2018-10-04 14:49:56 +0200

xen/arch/x86/spec_ctrl.c

@@ -214,12 +214,6 @@ static __init int parse_pv_l1tf(char *s)
     char *ss;
     int val, rc = 0;
 
-    /* Inhibit the defaults as an explicit choice has been given. */
-    if ( opt_pv_l1tf_hwdom == -1 )
-        opt_pv_l1tf_hwdom = 0;
-    if ( opt_pv_l1tf_domu == -1 )
-        opt_pv_l1tf_domu = 0;
-
     /* Interpret 'pv-l1tf' alone in its positive boolean form. */
     if ( *s == '\0' )
         opt_pv_l1tf_hwdom = opt_pv_l1tf_domu = 1;
@@ -674,12 +668,6 @@ static __init int parse_xpti(char *s)
     char *ss;
     int val, rc = 0;
 
-    /* Inhibit the defaults as an explicit choice has been given. */
-    if ( opt_xpti_hwdom == -1 )
-        opt_xpti_hwdom = 0;
-    if ( opt_xpti_domu == -1 )
-        opt_xpti_domu = 0;
-
     /* Interpret 'xpti' alone in its positive boolean form. */
     if ( *s == '\0' )
         opt_xpti_hwdom = opt_xpti_domu = 1;