UBUNTU: SAUCE: x86/speculation: Move RSB_CTXSW hunk

Move the RSB_CTXSW hunk further up in spectre_v2_select_mitigation() to
match upstream. No functional changes.

CVE-2017-5715
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/x86/kernel/cpu/bugs.c

@@ -410,16 +410,6 @@ static void __init spectre_v2_select_mitigation(void)
 	spectre_v2_enabled = mode;
 	pr_info("%s\n", spectre_v2_strings[mode]);
 
-	/*
-	 * Initialize Indirect Branch Prediction Barrier if supported and not
-	 * disabled on the commandline
-	 */
-	if (boot_cpu_has(X86_FEATURE_IBPB)) {
-		setup_force_cpu_cap(X86_FEATURE_USE_IBPB);
-		if (!noibpb)
-			set_ibpb_enabled(1);   /* Enable IBPB */
-	}
-
 	/*
 	 * If spectre v2 protection has been enabled, unconditionally fill
 	 * RSB during a context switch; this protects against two independent
@@ -431,6 +421,16 @@ static void __init spectre_v2_select_mitigation(void)
 	setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
 	pr_info("Spectre v2 / SpectreRSB mitigation: Filling RSB on context switch\n");
 
+	/*
+	 * Initialize Indirect Branch Prediction Barrier if supported and not
+	 * disabled on the commandline
+	 */
+	if (boot_cpu_has(X86_FEATURE_IBPB)) {
+		setup_force_cpu_cap(X86_FEATURE_USE_IBPB);
+		if (!noibpb)
+			set_ibpb_enabled(1);   /* Enable IBPB */
+	}
+
 	/*
 	 * Retpoline means the kernel is safe because it has no indirect
 	 * branches. Enhanced IBRS protects firmware too, so, enable restricted