[PATCH v6 13/21] x86/bugs: Add attack vector controls for spectre_v2_user

[David Kaplan <david.kaplan@amd.com>]

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

Signed-off-by: David Kaplan <david.kaplan@amd.com>
---
 arch/x86/kernel/cpu/bugs.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 1e2dab9be7db..f331cd70b0b4 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1725,7 +1725,7 @@ static enum spectre_v2_user_cmd __init spectre_v2_parse_user_cmdline(void)
 	char arg[20];
 	int ret, i;
 
-	if (cpu_mitigations_off() || !IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2))
+	if (!IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2))
 		return SPECTRE_V2_USER_CMD_NONE;
 
 	ret = cmdline_find_option(boot_command_line, "spectre_v2_user",
@@ -1763,6 +1763,13 @@ static void __init 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(X86_BUG_SPECTRE_V2_USER))
+			break;
+		spectre_v2_user_ibpb = SPECTRE_V2_USER_PRCTL;
+		if (smt_mitigations == SMT_MITIGATIONS_OFF)
+			break;
+		spectre_v2_user_stibp = SPECTRE_V2_USER_PRCTL;
+		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