powerpc/64s: Enhance the information in cpu_show_spectre_v1()

BugLink: https://bugs.launchpad.net/bugs/1830176

commit a3775145 upstream.

We now have barrier_nospec as mitigation so print it in
cpu_show_spectre_v1() when enabled.
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/powerpc/kernel/security.c

@@ -122,6 +122,9 @@ ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, c
 	if (!security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR))
 		return sprintf(buf, "Not affected\n");
 
+	if (barrier_nospec_enabled)
+		return sprintf(buf, "Mitigation: __user pointer sanitization\n");
+
 	return sprintf(buf, "Vulnerable\n");
 }