[PATCH 4.15 28/60] x86/spectre: Check CONFIG_RETPOLINE in command line parser

[Greg Kroah-Hartman]

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dou Liyang douly.fnst@xxxxxxxxxxxxxx

commit 9471eee9186a46893726e22ebb54cade3f9bc043

The spectre_v2 option 'auto' does not check whether CONFIG_RETPOLINE is
enabled. As a consequence it fails to emit the appropriate warning and sets
feature flags which have no effect at all.

Add the missing IS_ENABLED() check.

Fixes: da285121560e ("x86/spectre: Add boot time option to select Spectre v2 mitigation")
Signed-off-by: Dou Liyang <douly.fnst@xxxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: ak@xxxxxxxxxxxxxxx
Cc: peterz@xxxxxxxxxxxxx
Cc: Tomohiro <misono.tomohiro@xxxxxxxxxxxxxx>
Cc: dave.hansen@xxxxxxxxx
Cc: bp@xxxxxxxxx
Cc: arjan@xxxxxxxxxxxxxxx
Cc: dwmw@xxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/f5892721-7528-3647-08fb-f8d10e65ad87@xxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>


---
 arch/x86/kernel/cpu/bugs.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -213,10 +213,10 @@ static void __init spectre_v2_select_mit
 		return;
 
 	case SPECTRE_V2_CMD_FORCE:
-		/* FALLTRHU */
 	case SPECTRE_V2_CMD_AUTO:
-		goto retpoline_auto;
-
+		if (IS_ENABLED(CONFIG_RETPOLINE))
+			goto retpoline_auto;
+		break;
 	case SPECTRE_V2_CMD_RETPOLINE_AMD:
 		if (IS_ENABLED(CONFIG_RETPOLINE))
 			goto retpoline_amd;