[RFC PATCH 32/34] x86/bugs: Add attack vector controls for l1tf

[David Kaplan]

Use attack vector controls to determine if l1tf mitigation is required.

Disable SMT if cross-thread attack vector option is selected.

Signed-off-by: David Kaplan <david.kaplan@xxxxxxx>
---
 arch/x86/kernel/cpu/bugs.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 9c920e2b4f33..3be3431c20c0 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -2700,10 +2700,15 @@ static void __init l1tf_select_mitigation(void)
 	}
 
 	if (l1tf_mitigation == L1TF_MITIGATION_AUTO) {
-		if (cpu_mitigations_auto_nosmt())
-			l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT;
-		else
-			l1tf_mitigation = L1TF_MITIGATION_FLUSH;
+		if (!should_mitigate_vuln(L1TF))
+			l1tf_mitigation = L1TF_MITIGATION_OFF;
+		else {
+			if (cpu_mitigations_auto_nosmt() ||
+			    cpu_mitigate_attack_vector(CPU_MITIGATE_CROSS_THREAD))
+				l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT;
+			else
+				l1tf_mitigation = L1TF_MITIGATION_FLUSH;
+		}
 	}
 
 }
-- 
2.34.1