[RFC PATCH 29/34] x86/bugs: Add attack vector controls for spectre_v2_user

[David Kaplan]

Use attack vector controls to determine if spectre_v2_user mitigation is
required.

Signed-off-by: David Kaplan <david.kaplan@xxxxxxx>
---
 arch/x86/kernel/cpu/bugs.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 2659feb33090..9859f650f25f 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1530,6 +1530,13 @@ spectre_v2_user_select_mitigation(void)
 		spectre_v2_user_stibp = SPECTRE_V2_USER_STRICT;
 		break;
 	case SPECTRE_V2_USER_CMD_AUTO:
+		if (should_mitigate_vuln(SPECTRE_V2_USER)) {
+			spectre_v2_user_ibpb = SPECTRE_V2_USER_PRCTL;
+			spectre_v2_user_stibp = SPECTRE_V2_USER_PRCTL;
+		} else {
+			return;
+		}
+		break;
 	case SPECTRE_V2_USER_CMD_PRCTL:
 		spectre_v2_user_ibpb = SPECTRE_V2_USER_PRCTL;
 		spectre_v2_user_stibp = SPECTRE_V2_USER_PRCTL;
-- 
2.34.1