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-rw-r--r--arch/x86/kernel/cpu/bugs.c58
1 files changed, 46 insertions, 12 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index bdeb732ff2d9..fb249b2c1eb0 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -783,19 +783,34 @@ static enum retbleed_mitigation retbleed_mitigation __ro_after_init =
static enum retbleed_mitigation_cmd retbleed_cmd __ro_after_init =
RETBLEED_CMD_AUTO;
+static int __ro_after_init retbleed_nosmt = false;
+
static int __init retbleed_parse_cmdline(char *str)
{
if (!str)
return -EINVAL;
- if (!strcmp(str, "off"))
- retbleed_cmd = RETBLEED_CMD_OFF;
- else if (!strcmp(str, "auto"))
- retbleed_cmd = RETBLEED_CMD_AUTO;
- else if (!strcmp(str, "unret"))
- retbleed_cmd = RETBLEED_CMD_UNRET;
- else
- pr_err("Unknown retbleed option (%s). Defaulting to 'auto'\n", str);
+ while (str) {
+ char *next = strchr(str, ',');
+ if (next) {
+ *next = 0;
+ next++;
+ }
+
+ if (!strcmp(str, "off")) {
+ retbleed_cmd = RETBLEED_CMD_OFF;
+ } else if (!strcmp(str, "auto")) {
+ retbleed_cmd = RETBLEED_CMD_AUTO;
+ } else if (!strcmp(str, "unret")) {
+ retbleed_cmd = RETBLEED_CMD_UNRET;
+ } else if (!strcmp(str, "nosmt")) {
+ retbleed_nosmt = true;
+ } else {
+ pr_err("Ignoring unknown retbleed option (%s).", str);
+ }
+
+ str = next;
+ }
return 0;
}
@@ -841,6 +856,10 @@ static void __init retbleed_select_mitigation(void)
setup_force_cpu_cap(X86_FEATURE_RETHUNK);
setup_force_cpu_cap(X86_FEATURE_UNRET);
+ if (!boot_cpu_has(X86_FEATURE_STIBP) &&
+ (retbleed_nosmt || cpu_mitigations_auto_nosmt()))
+ cpu_smt_disable(false);
+
if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
pr_err(RETBLEED_UNTRAIN_MSG);
@@ -1087,6 +1106,13 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON))
mode = SPECTRE_V2_USER_STRICT_PREFERRED;
+ if (retbleed_mitigation == RETBLEED_MITIGATION_UNRET) {
+ if (mode != SPECTRE_V2_USER_STRICT &&
+ mode != SPECTRE_V2_USER_STRICT_PREFERRED)
+ pr_info("Selecting STIBP always-on mode to complement retbleed mitigation'\n");
+ mode = SPECTRE_V2_USER_STRICT_PREFERRED;
+ }
+
spectre_v2_user_stibp = mode;
set_mode:
@@ -2097,10 +2123,18 @@ static ssize_t srbds_show_state(char *buf)
static ssize_t retbleed_show_state(char *buf)
{
- if (retbleed_mitigation == RETBLEED_MITIGATION_UNRET &&
- (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
- boot_cpu_data.x86_vendor != X86_VENDOR_HYGON))
- return sprintf(buf, "Vulnerable: untrained return thunk on non-Zen uarch\n");
+ if (retbleed_mitigation == RETBLEED_MITIGATION_UNRET) {
+ if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
+ boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
+ return sprintf(buf, "Vulnerable: untrained return thunk on non-Zen uarch\n");
+
+ return sprintf(buf, "%s; SMT %s\n",
+ retbleed_strings[retbleed_mitigation],
+ !sched_smt_active() ? "disabled" :
+ spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT ||
+ spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED ?
+ "enabled with STIBP protection" : "vulnerable");
+ }
return sprintf(buf, "%s\n", retbleed_strings[retbleed_mitigation]);
}