[PATCH v6 18/21] x86/bugs: Add attack vector controls for ITS

[David Kaplan]

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

Signed-off-by: David Kaplan <david.kaplan@xxxxxxx>
---
 arch/x86/kernel/cpu/bugs.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index c0e23e625b6f..7972c9b16e8a 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1514,13 +1514,17 @@ early_param("indirect_target_selection", its_parse_cmdline);
 
 static void __init its_select_mitigation(void)
 {
-	if (!boot_cpu_has_bug(X86_BUG_ITS) || cpu_mitigations_off()) {
+	if (!boot_cpu_has_bug(X86_BUG_ITS)) {
 		its_mitigation = ITS_MITIGATION_OFF;
 		return;
 	}
 
-	if (its_mitigation == ITS_MITIGATION_AUTO)
-		its_mitigation = ITS_MITIGATION_ALIGNED_THUNKS;
+	if (its_mitigation == ITS_MITIGATION_AUTO) {
+		if (should_mitigate_vuln(X86_BUG_ITS))
+			its_mitigation = ITS_MITIGATION_ALIGNED_THUNKS;
+		else
+			its_mitigation = ITS_MITIGATION_OFF;
+	}
 
 	if (its_mitigation == ITS_MITIGATION_OFF)
 		return;
@@ -1551,12 +1555,13 @@ static void __init its_select_mitigation(void)
 
 static void __init its_update_mitigation(void)
 {
-	if (!boot_cpu_has_bug(X86_BUG_ITS) || cpu_mitigations_off())
+	if (!boot_cpu_has_bug(X86_BUG_ITS))
 		return;
 
 	switch (spectre_v2_enabled) {
 	case SPECTRE_V2_NONE:
-		pr_err("WARNING: Spectre-v2 mitigation is off, disabling ITS\n");
+		if (its_mitigation != ITS_MITIGATION_OFF)
+			pr_err("WARNING: Spectre-v2 mitigation is off, disabling ITS\n");
 		its_mitigation = ITS_MITIGATION_OFF;
 		break;
 	case SPECTRE_V2_RETPOLINE:
-- 
2.34.1