[tip:x86/pti] x86/spectre: Check CONFIG_RETPOLINE in command line parser

[tip-bot for Dou Liyang]

Commit-ID:  9471eee9186a46893726e22ebb54cade3f9bc043
Gitweb:     https://git.kernel.org/tip/9471eee9186a46893726e22ebb54cade3f9bc043
Author:     Dou Liyang <douly.fnst@xxxxxxxxxxxxxx>
AuthorDate: Tue, 30 Jan 2018 14:13:50 +0800
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Tue, 30 Jan 2018 15:30:35 +0100

x86/spectre: Check CONFIG_RETPOLINE in command line parser

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

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

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 3bfb2b2..400c34e 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -213,10 +213,10 @@ static void __init spectre_v2_select_mitigation(void)
 		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;