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Diffstat (limited to 'arch/x86/kernel/cpu/bugs.c')
-rw-r--r--arch/x86/kernel/cpu/bugs.c170
1 files changed, 129 insertions, 41 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 01ac18f561..e7ceee008b 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -61,6 +61,8 @@ EXPORT_SYMBOL_GPL(x86_spec_ctrl_current);
u64 x86_pred_cmd __ro_after_init = PRED_CMD_IBPB;
EXPORT_SYMBOL_GPL(x86_pred_cmd);
+static u64 __ro_after_init x86_arch_cap_msr;
+
static DEFINE_MUTEX(spec_ctrl_mutex);
void (*x86_return_thunk)(void) __ro_after_init = __x86_return_thunk;
@@ -144,6 +146,8 @@ void __init cpu_select_mitigations(void)
x86_spec_ctrl_base &= ~SPEC_CTRL_MITIGATIONS_MASK;
}
+ x86_arch_cap_msr = x86_read_arch_cap_msr();
+
/* Select the proper CPU mitigations before patching alternatives: */
spectre_v1_select_mitigation();
spectre_v2_select_mitigation();
@@ -301,8 +305,6 @@ static const char * const taa_strings[] = {
static void __init taa_select_mitigation(void)
{
- u64 ia32_cap;
-
if (!boot_cpu_has_bug(X86_BUG_TAA)) {
taa_mitigation = TAA_MITIGATION_OFF;
return;
@@ -341,9 +343,8 @@ static void __init taa_select_mitigation(void)
* On MDS_NO=1 CPUs if ARCH_CAP_TSX_CTRL_MSR is not set, microcode
* update is required.
*/
- ia32_cap = x86_read_arch_cap_msr();
- if ( (ia32_cap & ARCH_CAP_MDS_NO) &&
- !(ia32_cap & ARCH_CAP_TSX_CTRL_MSR))
+ if ( (x86_arch_cap_msr & ARCH_CAP_MDS_NO) &&
+ !(x86_arch_cap_msr & ARCH_CAP_TSX_CTRL_MSR))
taa_mitigation = TAA_MITIGATION_UCODE_NEEDED;
/*
@@ -401,8 +402,6 @@ static const char * const mmio_strings[] = {
static void __init mmio_select_mitigation(void)
{
- u64 ia32_cap;
-
if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA) ||
boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN) ||
cpu_mitigations_off()) {
@@ -413,8 +412,6 @@ static void __init mmio_select_mitigation(void)
if (mmio_mitigation == MMIO_MITIGATION_OFF)
return;
- ia32_cap = x86_read_arch_cap_msr();
-
/*
* Enable CPU buffer clear mitigation for host and VMM, if also affected
* by MDS or TAA. Otherwise, enable mitigation for VMM only.
@@ -437,7 +434,7 @@ static void __init mmio_select_mitigation(void)
* be propagated to uncore buffers, clearing the Fill buffers on idle
* is required irrespective of SMT state.
*/
- if (!(ia32_cap & ARCH_CAP_FBSDP_NO))
+ if (!(x86_arch_cap_msr & ARCH_CAP_FBSDP_NO))
static_branch_enable(&mds_idle_clear);
/*
@@ -447,10 +444,10 @@ static void __init mmio_select_mitigation(void)
* FB_CLEAR or by the presence of both MD_CLEAR and L1D_FLUSH on MDS
* affected systems.
*/
- if ((ia32_cap & ARCH_CAP_FB_CLEAR) ||
+ if ((x86_arch_cap_msr & ARCH_CAP_FB_CLEAR) ||
(boot_cpu_has(X86_FEATURE_MD_CLEAR) &&
boot_cpu_has(X86_FEATURE_FLUSH_L1D) &&
- !(ia32_cap & ARCH_CAP_MDS_NO)))
+ !(x86_arch_cap_msr & ARCH_CAP_MDS_NO)))
mmio_mitigation = MMIO_MITIGATION_VERW;
else
mmio_mitigation = MMIO_MITIGATION_UCODE_NEEDED;
@@ -508,7 +505,7 @@ static void __init rfds_select_mitigation(void)
if (rfds_mitigation == RFDS_MITIGATION_OFF)
return;
- if (x86_read_arch_cap_msr() & ARCH_CAP_RFDS_CLEAR)
+ if (x86_arch_cap_msr & ARCH_CAP_RFDS_CLEAR)
setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF);
else
rfds_mitigation = RFDS_MITIGATION_UCODE_NEEDED;
@@ -659,8 +656,6 @@ void update_srbds_msr(void)
static void __init srbds_select_mitigation(void)
{
- u64 ia32_cap;
-
if (!boot_cpu_has_bug(X86_BUG_SRBDS))
return;
@@ -669,8 +664,7 @@ static void __init srbds_select_mitigation(void)
* are only exposed to SRBDS when TSX is enabled or when CPU is affected
* by Processor MMIO Stale Data vulnerability.
*/
- ia32_cap = x86_read_arch_cap_msr();
- if ((ia32_cap & ARCH_CAP_MDS_NO) && !boot_cpu_has(X86_FEATURE_RTM) &&
+ if ((x86_arch_cap_msr & ARCH_CAP_MDS_NO) && !boot_cpu_has(X86_FEATURE_RTM) &&
!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA))
srbds_mitigation = SRBDS_MITIGATION_TSX_OFF;
else if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
@@ -813,7 +807,7 @@ static void __init gds_select_mitigation(void)
/* Will verify below that mitigation _can_ be disabled */
/* No microcode */
- if (!(x86_read_arch_cap_msr() & ARCH_CAP_GDS_CTRL)) {
+ if (!(x86_arch_cap_msr & ARCH_CAP_GDS_CTRL)) {
if (gds_mitigation == GDS_MITIGATION_FORCE) {
/*
* This only needs to be done on the boot CPU so do it
@@ -1543,20 +1537,25 @@ static enum spectre_v2_mitigation __init spectre_v2_select_retpoline(void)
return SPECTRE_V2_RETPOLINE;
}
+static bool __ro_after_init rrsba_disabled;
+
/* Disable in-kernel use of non-RSB RET predictors */
static void __init spec_ctrl_disable_kernel_rrsba(void)
{
- u64 ia32_cap;
+ if (rrsba_disabled)
+ return;
- if (!boot_cpu_has(X86_FEATURE_RRSBA_CTRL))
+ if (!(x86_arch_cap_msr & ARCH_CAP_RRSBA)) {
+ rrsba_disabled = true;
return;
+ }
- ia32_cap = x86_read_arch_cap_msr();
+ if (!boot_cpu_has(X86_FEATURE_RRSBA_CTRL))
+ return;
- if (ia32_cap & ARCH_CAP_RRSBA) {
- x86_spec_ctrl_base |= SPEC_CTRL_RRSBA_DIS_S;
- update_spec_ctrl(x86_spec_ctrl_base);
- }
+ x86_spec_ctrl_base |= SPEC_CTRL_RRSBA_DIS_S;
+ update_spec_ctrl(x86_spec_ctrl_base);
+ rrsba_disabled = true;
}
static void __init spectre_v2_determine_rsb_fill_type_at_vmexit(enum spectre_v2_mitigation mode)
@@ -1606,6 +1605,74 @@ static void __init spectre_v2_determine_rsb_fill_type_at_vmexit(enum spectre_v2_
dump_stack();
}
+/*
+ * Set BHI_DIS_S to prevent indirect branches in kernel to be influenced by
+ * branch history in userspace. Not needed if BHI_NO is set.
+ */
+static bool __init spec_ctrl_bhi_dis(void)
+{
+ if (!boot_cpu_has(X86_FEATURE_BHI_CTRL))
+ return false;
+
+ x86_spec_ctrl_base |= SPEC_CTRL_BHI_DIS_S;
+ update_spec_ctrl(x86_spec_ctrl_base);
+ setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_HW);
+
+ return true;
+}
+
+enum bhi_mitigations {
+ BHI_MITIGATION_OFF,
+ BHI_MITIGATION_ON,
+};
+
+static enum bhi_mitigations bhi_mitigation __ro_after_init =
+ IS_ENABLED(CONFIG_MITIGATION_SPECTRE_BHI) ? BHI_MITIGATION_ON : BHI_MITIGATION_OFF;
+
+static int __init spectre_bhi_parse_cmdline(char *str)
+{
+ if (!str)
+ return -EINVAL;
+
+ if (!strcmp(str, "off"))
+ bhi_mitigation = BHI_MITIGATION_OFF;
+ else if (!strcmp(str, "on"))
+ bhi_mitigation = BHI_MITIGATION_ON;
+ else
+ pr_err("Ignoring unknown spectre_bhi option (%s)", str);
+
+ return 0;
+}
+early_param("spectre_bhi", spectre_bhi_parse_cmdline);
+
+static void __init bhi_select_mitigation(void)
+{
+ if (bhi_mitigation == BHI_MITIGATION_OFF)
+ return;
+
+ /* Retpoline mitigates against BHI unless the CPU has RRSBA behavior */
+ if (boot_cpu_has(X86_FEATURE_RETPOLINE) &&
+ !boot_cpu_has(X86_FEATURE_RETPOLINE_LFENCE)) {
+ spec_ctrl_disable_kernel_rrsba();
+ if (rrsba_disabled)
+ return;
+ }
+
+ if (spec_ctrl_bhi_dis())
+ return;
+
+ if (!IS_ENABLED(CONFIG_X86_64))
+ return;
+
+ /* Mitigate KVM by default */
+ setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT);
+ pr_info("Spectre BHI mitigation: SW BHB clearing on vm exit\n");
+
+ /* Mitigate syscalls when the mitigation is forced =on */
+ setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_LOOP);
+ pr_info("Spectre BHI mitigation: SW BHB clearing on syscall\n");
+}
+
static void __init spectre_v2_select_mitigation(void)
{
enum spectre_v2_mitigation_cmd cmd = spectre_v2_parse_cmdline();
@@ -1717,6 +1784,9 @@ static void __init spectre_v2_select_mitigation(void)
mode == SPECTRE_V2_RETPOLINE)
spec_ctrl_disable_kernel_rrsba();
+ if (boot_cpu_has(X86_BUG_BHI))
+ bhi_select_mitigation();
+
spectre_v2_enabled = mode;
pr_info("%s\n", spectre_v2_strings[mode]);
@@ -1831,8 +1901,6 @@ static void update_indir_branch_cond(void)
/* Update the static key controlling the MDS CPU buffer clear in idle */
static void update_mds_branch_idle(void)
{
- u64 ia32_cap = x86_read_arch_cap_msr();
-
/*
* Enable the idle clearing if SMT is active on CPUs which are
* affected only by MSBDS and not any other MDS variant.
@@ -1847,7 +1915,7 @@ static void update_mds_branch_idle(void)
if (sched_smt_active()) {
static_branch_enable(&mds_idle_clear);
} else if (mmio_mitigation == MMIO_MITIGATION_OFF ||
- (ia32_cap & ARCH_CAP_FBSDP_NO)) {
+ (x86_arch_cap_msr & ARCH_CAP_FBSDP_NO)) {
static_branch_disable(&mds_idle_clear);
}
}
@@ -2694,15 +2762,15 @@ static char *stibp_state(void)
switch (spectre_v2_user_stibp) {
case SPECTRE_V2_USER_NONE:
- return ", STIBP: disabled";
+ return "; STIBP: disabled";
case SPECTRE_V2_USER_STRICT:
- return ", STIBP: forced";
+ return "; STIBP: forced";
case SPECTRE_V2_USER_STRICT_PREFERRED:
- return ", STIBP: always-on";
+ return "; STIBP: always-on";
case SPECTRE_V2_USER_PRCTL:
case SPECTRE_V2_USER_SECCOMP:
if (static_key_enabled(&switch_to_cond_stibp))
- return ", STIBP: conditional";
+ return "; STIBP: conditional";
}
return "";
}
@@ -2711,10 +2779,10 @@ static char *ibpb_state(void)
{
if (boot_cpu_has(X86_FEATURE_IBPB)) {
if (static_key_enabled(&switch_mm_always_ibpb))
- return ", IBPB: always-on";
+ return "; IBPB: always-on";
if (static_key_enabled(&switch_mm_cond_ibpb))
- return ", IBPB: conditional";
- return ", IBPB: disabled";
+ return "; IBPB: conditional";
+ return "; IBPB: disabled";
}
return "";
}
@@ -2724,14 +2792,32 @@ static char *pbrsb_eibrs_state(void)
if (boot_cpu_has_bug(X86_BUG_EIBRS_PBRSB)) {
if (boot_cpu_has(X86_FEATURE_RSB_VMEXIT_LITE) ||
boot_cpu_has(X86_FEATURE_RSB_VMEXIT))
- return ", PBRSB-eIBRS: SW sequence";
+ return "; PBRSB-eIBRS: SW sequence";
else
- return ", PBRSB-eIBRS: Vulnerable";
+ return "; PBRSB-eIBRS: Vulnerable";
} else {
- return ", PBRSB-eIBRS: Not affected";
+ return "; PBRSB-eIBRS: Not affected";
}
}
+static const char *spectre_bhi_state(void)
+{
+ if (!boot_cpu_has_bug(X86_BUG_BHI))
+ return "; BHI: Not affected";
+ else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_HW))
+ return "; BHI: BHI_DIS_S";
+ else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP))
+ return "; BHI: SW loop, KVM: SW loop";
+ else if (boot_cpu_has(X86_FEATURE_RETPOLINE) &&
+ !boot_cpu_has(X86_FEATURE_RETPOLINE_LFENCE) &&
+ rrsba_disabled)
+ return "; BHI: Retpoline";
+ else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT))
+ return "; BHI: Vulnerable, KVM: SW loop";
+
+ return "; BHI: Vulnerable";
+}
+
static ssize_t spectre_v2_show_state(char *buf)
{
if (spectre_v2_enabled == SPECTRE_V2_LFENCE)
@@ -2744,13 +2830,15 @@ static ssize_t spectre_v2_show_state(char *buf)
spectre_v2_enabled == SPECTRE_V2_EIBRS_LFENCE)
return sysfs_emit(buf, "Vulnerable: eIBRS+LFENCE with unprivileged eBPF and SMT\n");
- return sysfs_emit(buf, "%s%s%s%s%s%s%s\n",
+ return sysfs_emit(buf, "%s%s%s%s%s%s%s%s\n",
spectre_v2_strings[spectre_v2_enabled],
ibpb_state(),
- boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "",
+ boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? "; IBRS_FW" : "",
stibp_state(),
- boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "",
+ boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? "; RSB filling" : "",
pbrsb_eibrs_state(),
+ spectre_bhi_state(),
+ /* this should always be at the end */
spectre_v2_module_string());
}