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Diffstat (limited to 'arch/x86/kernel/cpu/bugs.c')
-rw-r--r--arch/x86/kernel/cpu/bugs.c82
1 files changed, 36 insertions, 46 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 50fdd6ca3b78..b30b32b288dd 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -60,6 +60,8 @@ 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;
@@ -143,6 +145,8 @@ 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();
@@ -307,8 +311,6 @@ 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;
@@ -347,9 +349,8 @@ 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;
/*
@@ -407,8 +408,6 @@ 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()) {
@@ -419,8 +418,6 @@ 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.
@@ -443,7 +440,7 @@ 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);
/*
@@ -453,10 +450,10 @@ 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;
@@ -514,7 +511,7 @@ 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;
@@ -658,8 +655,6 @@ void update_srbds_msr(void)
static void __init srbds_select_mitigation(void)
{
- u64 ia32_cap;
-
if (!boot_cpu_has_bug(X86_BUG_SRBDS))
return;
@@ -668,8 +663,7 @@ 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))
@@ -812,7 +806,7 @@ 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
@@ -1521,20 +1515,25 @@ 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)
@@ -1603,13 +1602,10 @@ static bool __init spec_ctrl_bhi_dis(void)
enum bhi_mitigations {
BHI_MITIGATION_OFF,
BHI_MITIGATION_ON,
- BHI_MITIGATION_AUTO,
};
static enum bhi_mitigations bhi_mitigation __ro_after_init =
- IS_ENABLED(CONFIG_SPECTRE_BHI_ON) ? BHI_MITIGATION_ON :
- IS_ENABLED(CONFIG_SPECTRE_BHI_OFF) ? BHI_MITIGATION_OFF :
- BHI_MITIGATION_AUTO;
+ IS_ENABLED(CONFIG_MITIGATION_SPECTRE_BHI) ? BHI_MITIGATION_ON : BHI_MITIGATION_OFF;
static int __init spectre_bhi_parse_cmdline(char *str)
{
@@ -1620,8 +1616,6 @@ static int __init spectre_bhi_parse_cmdline(char *str)
bhi_mitigation = BHI_MITIGATION_OFF;
else if (!strcmp(str, "on"))
bhi_mitigation = BHI_MITIGATION_ON;
- else if (!strcmp(str, "auto"))
- bhi_mitigation = BHI_MITIGATION_AUTO;
else
pr_err("Ignoring unknown spectre_bhi option (%s)", str);
@@ -1635,9 +1629,11 @@ static void __init bhi_select_mitigation(void)
return;
/* Retpoline mitigates against BHI unless the CPU has RRSBA behavior */
- if (cpu_feature_enabled(X86_FEATURE_RETPOLINE) &&
- !(x86_read_arch_cap_msr() & ARCH_CAP_RRSBA))
- return;
+ if (cpu_feature_enabled(X86_FEATURE_RETPOLINE)) {
+ spec_ctrl_disable_kernel_rrsba();
+ if (rrsba_disabled)
+ return;
+ }
if (spec_ctrl_bhi_dis())
return;
@@ -1649,9 +1645,6 @@ static void __init bhi_select_mitigation(void)
setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT);
pr_info("Spectre BHI mitigation: SW BHB clearing on vm exit\n");
- if (bhi_mitigation == BHI_MITIGATION_AUTO)
- return;
-
/* 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");
@@ -1884,8 +1877,6 @@ 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.
@@ -1900,7 +1891,7 @@ 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);
}
}
@@ -2788,7 +2779,7 @@ static char *pbrsb_eibrs_state(void)
}
}
-static const char * const spectre_bhi_state(void)
+static const char *spectre_bhi_state(void)
{
if (!boot_cpu_has_bug(X86_BUG_BHI))
return "; BHI: Not affected";
@@ -2796,13 +2787,12 @@ static const char * const spectre_bhi_state(void)
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) &&
- !(x86_read_arch_cap_msr() & ARCH_CAP_RRSBA))
+ else if (boot_cpu_has(X86_FEATURE_RETPOLINE) && rrsba_disabled)
return "; BHI: Retpoline";
- else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT))
- return "; BHI: Syscall hardening, KVM: SW loop";
+ else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT))
+ return "; BHI: Vulnerable, KVM: SW loop";
- return "; BHI: Vulnerable (Syscall hardening enabled)";
+ return "; BHI: Vulnerable";
}
static ssize_t spectre_v2_show_state(char *buf)
generated by cgit 1.2.3-korg (git 2.39.0) at 2024-04-30 23:07:27 +0000