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Diffstat (limited to 'arch/x86/kernel/cpu/bugs.c')
-rw-r--r--arch/x86/kernel/cpu/bugs.c62
1 files changed, 55 insertions, 7 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 40bdaea97fe7..c37e66e493bf 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -35,12 +35,10 @@ static void __init spectre_v2_select_mitigation(void);
static void __init ssb_select_mitigation(void);
static void __init l1tf_select_mitigation(void);
-/*
- * Our boot-time value of the SPEC_CTRL MSR. We read it once so that any
- * writes to SPEC_CTRL contain whatever reserved bits have been set.
- */
-u64 __ro_after_init x86_spec_ctrl_base;
+/* The base value of the SPEC_CTRL MSR that always has to be preserved. */
+u64 x86_spec_ctrl_base;
EXPORT_SYMBOL_GPL(x86_spec_ctrl_base);
+static DEFINE_MUTEX(spec_ctrl_mutex);
/*
* The vendor and possibly platform specific bits which can be modified in
@@ -312,6 +310,7 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
}
if (cmd == SPECTRE_V2_CMD_RETPOLINE_AMD &&
+ boot_cpu_data.x86_vendor != X86_VENDOR_HYGON &&
boot_cpu_data.x86_vendor != X86_VENDOR_AMD) {
pr_err("retpoline,amd selected but CPU is not AMD. Switching to AUTO select\n");
return SPECTRE_V2_CMD_AUTO;
@@ -325,6 +324,46 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
return cmd;
}
+static bool stibp_needed(void)
+{
+ if (spectre_v2_enabled == SPECTRE_V2_NONE)
+ return false;
+
+ if (!boot_cpu_has(X86_FEATURE_STIBP))
+ return false;
+
+ return true;
+}
+
+static void update_stibp_msr(void *info)
+{
+ wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
+}
+
+void arch_smt_update(void)
+{
+ u64 mask;
+
+ if (!stibp_needed())
+ return;
+
+ mutex_lock(&spec_ctrl_mutex);
+ mask = x86_spec_ctrl_base;
+ if (cpu_smt_control == CPU_SMT_ENABLED)
+ mask |= SPEC_CTRL_STIBP;
+ else
+ mask &= ~SPEC_CTRL_STIBP;
+
+ if (mask != x86_spec_ctrl_base) {
+ pr_info("Spectre v2 cross-process SMT mitigation: %s STIBP\n",
+ cpu_smt_control == CPU_SMT_ENABLED ?
+ "Enabling" : "Disabling");
+ x86_spec_ctrl_base = mask;
+ on_each_cpu(update_stibp_msr, NULL, 1);
+ }
+ mutex_unlock(&spec_ctrl_mutex);
+}
+
static void __init spectre_v2_select_mitigation(void)
{
enum spectre_v2_mitigation_cmd cmd = spectre_v2_parse_cmdline();
@@ -371,7 +410,8 @@ static void __init spectre_v2_select_mitigation(void)
return;
retpoline_auto:
- if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
+ if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
+ boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
retpoline_amd:
if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
pr_err("Spectre mitigation: LFENCE not serializing, switching to generic retpoline\n");
@@ -424,6 +464,9 @@ specv2_set_mode:
setup_force_cpu_cap(X86_FEATURE_USE_IBRS_FW);
pr_info("Enabling Restricted Speculation for firmware calls\n");
}
+
+ /* Enable STIBP if appropriate */
+ arch_smt_update();
}
#undef pr_fmt
@@ -814,6 +857,8 @@ static ssize_t l1tf_show_state(char *buf)
static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr,
char *buf, unsigned int bug)
{
+ int ret;
+
if (!boot_cpu_has_bug(bug))
return sprintf(buf, "Not affected\n");
@@ -831,10 +876,13 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr
return sprintf(buf, "Mitigation: __user pointer sanitization\n");
case X86_BUG_SPECTRE_V2:
- return sprintf(buf, "%s%s%s%s\n", spectre_v2_strings[spectre_v2_enabled],
+ ret = sprintf(buf, "%s%s%s%s%s%s\n", spectre_v2_strings[spectre_v2_enabled],
boot_cpu_has(X86_FEATURE_USE_IBPB) ? ", IBPB" : "",
boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "",
+ (x86_spec_ctrl_base & SPEC_CTRL_STIBP) ? ", STIBP" : "",
+ boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "",
spectre_v2_module_string());
+ return ret;
case X86_BUG_SPEC_STORE_BYPASS:
return sprintf(buf, "%s\n", ssb_strings[ssb_mode]);