diff options
Diffstat (limited to 'arch/x86/kernel/cpu/bugs.c')
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 136 |
1 files changed, 130 insertions, 6 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 7f94e6a5497d..f4d3abb12317 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -94,6 +94,8 @@ static void __init bhi_apply_mitigation(void); static void __init its_select_mitigation(void); static void __init its_update_mitigation(void); static void __init its_apply_mitigation(void); +static void __init tsa_select_mitigation(void); +static void __init tsa_apply_mitigation(void); /* The base value of the SPEC_CTRL MSR without task-specific bits set */ u64 x86_spec_ctrl_base; @@ -169,9 +171,9 @@ DEFINE_STATIC_KEY_FALSE(switch_mm_always_ibpb); DEFINE_STATIC_KEY_FALSE(switch_vcpu_ibpb); EXPORT_SYMBOL_GPL(switch_vcpu_ibpb); -/* Control MDS CPU buffer clear before idling (halt, mwait) */ -DEFINE_STATIC_KEY_FALSE(mds_idle_clear); -EXPORT_SYMBOL_GPL(mds_idle_clear); +/* Control CPU buffer clear before idling (halt, mwait) */ +DEFINE_STATIC_KEY_FALSE(cpu_buf_idle_clear); +EXPORT_SYMBOL_GPL(cpu_buf_idle_clear); /* * Controls whether l1d flush based mitigations are enabled, @@ -225,6 +227,7 @@ void __init cpu_select_mitigations(void) gds_select_mitigation(); its_select_mitigation(); bhi_select_mitigation(); + tsa_select_mitigation(); /* * After mitigations are selected, some may need to update their @@ -272,6 +275,7 @@ void __init cpu_select_mitigations(void) gds_apply_mitigation(); its_apply_mitigation(); bhi_apply_mitigation(); + tsa_apply_mitigation(); } /* @@ -637,7 +641,7 @@ static void __init mmio_apply_mitigation(void) * is required irrespective of SMT state. */ if (!(x86_arch_cap_msr & ARCH_CAP_FBSDP_NO)) - static_branch_enable(&mds_idle_clear); + static_branch_enable(&cpu_buf_idle_clear); if (mmio_nosmt || cpu_mitigations_auto_nosmt()) cpu_smt_disable(false); @@ -1488,6 +1492,94 @@ static void __init its_apply_mitigation(void) } #undef pr_fmt +#define pr_fmt(fmt) "Transient Scheduler Attacks: " fmt + +enum tsa_mitigations { + TSA_MITIGATION_NONE, + TSA_MITIGATION_AUTO, + TSA_MITIGATION_UCODE_NEEDED, + TSA_MITIGATION_USER_KERNEL, + TSA_MITIGATION_VM, + TSA_MITIGATION_FULL, +}; + +static const char * const tsa_strings[] = { + [TSA_MITIGATION_NONE] = "Vulnerable", + [TSA_MITIGATION_UCODE_NEEDED] = "Vulnerable: No microcode", + [TSA_MITIGATION_USER_KERNEL] = "Mitigation: Clear CPU buffers: user/kernel boundary", + [TSA_MITIGATION_VM] = "Mitigation: Clear CPU buffers: VM", + [TSA_MITIGATION_FULL] = "Mitigation: Clear CPU buffers", +}; + +static enum tsa_mitigations tsa_mitigation __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_TSA) ? TSA_MITIGATION_AUTO : TSA_MITIGATION_NONE; + +static int __init tsa_parse_cmdline(char *str) +{ + if (!str) + return -EINVAL; + + if (!strcmp(str, "off")) + tsa_mitigation = TSA_MITIGATION_NONE; + else if (!strcmp(str, "on")) + tsa_mitigation = TSA_MITIGATION_FULL; + else if (!strcmp(str, "user")) + tsa_mitigation = TSA_MITIGATION_USER_KERNEL; + else if (!strcmp(str, "vm")) + tsa_mitigation = TSA_MITIGATION_VM; + else + pr_err("Ignoring unknown tsa=%s option.\n", str); + + return 0; +} +early_param("tsa", tsa_parse_cmdline); + +static void __init tsa_select_mitigation(void) +{ + if (cpu_mitigations_off() || !boot_cpu_has_bug(X86_BUG_TSA)) { + tsa_mitigation = TSA_MITIGATION_NONE; + return; + } + + if (tsa_mitigation == TSA_MITIGATION_NONE) + return; + + if (!boot_cpu_has(X86_FEATURE_VERW_CLEAR)) { + tsa_mitigation = TSA_MITIGATION_UCODE_NEEDED; + goto out; + } + + if (tsa_mitigation == TSA_MITIGATION_AUTO) + tsa_mitigation = TSA_MITIGATION_FULL; + + /* + * No need to set verw_clear_cpu_buf_mitigation_selected - it + * doesn't fit all cases here and it is not needed because this + * is the only VERW-based mitigation on AMD. + */ +out: + pr_info("%s\n", tsa_strings[tsa_mitigation]); +} + +static void __init tsa_apply_mitigation(void) +{ + switch (tsa_mitigation) { + case TSA_MITIGATION_USER_KERNEL: + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); + break; + case TSA_MITIGATION_VM: + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF_VM); + break; + case TSA_MITIGATION_FULL: + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF_VM); + break; + default: + break; + } +} + +#undef pr_fmt #define pr_fmt(fmt) "Spectre V2 : " fmt static enum spectre_v2_user_mitigation spectre_v2_user_stibp __ro_after_init = @@ -2249,10 +2341,10 @@ static void update_mds_branch_idle(void) return; if (sched_smt_active()) { - static_branch_enable(&mds_idle_clear); + static_branch_enable(&cpu_buf_idle_clear); } else if (mmio_mitigation == MMIO_MITIGATION_OFF || (x86_arch_cap_msr & ARCH_CAP_FBSDP_NO)) { - static_branch_disable(&mds_idle_clear); + static_branch_disable(&cpu_buf_idle_clear); } } @@ -2316,6 +2408,25 @@ void cpu_bugs_smt_update(void) break; } + switch (tsa_mitigation) { + case TSA_MITIGATION_USER_KERNEL: + case TSA_MITIGATION_VM: + case TSA_MITIGATION_AUTO: + case TSA_MITIGATION_FULL: + /* + * TSA-SQ can potentially lead to info leakage between + * SMT threads. + */ + if (sched_smt_active()) + static_branch_enable(&cpu_buf_idle_clear); + else + static_branch_disable(&cpu_buf_idle_clear); + break; + case TSA_MITIGATION_NONE: + case TSA_MITIGATION_UCODE_NEEDED: + break; + } + mutex_unlock(&spec_ctrl_mutex); } @@ -3265,6 +3376,11 @@ static ssize_t gds_show_state(char *buf) return sysfs_emit(buf, "%s\n", gds_strings[gds_mitigation]); } +static ssize_t tsa_show_state(char *buf) +{ + return sysfs_emit(buf, "%s\n", tsa_strings[tsa_mitigation]); +} + static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr, char *buf, unsigned int bug) { @@ -3328,6 +3444,9 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr case X86_BUG_ITS: return its_show_state(buf); + case X86_BUG_TSA: + return tsa_show_state(buf); + default: break; } @@ -3414,6 +3533,11 @@ ssize_t cpu_show_indirect_target_selection(struct device *dev, struct device_att { return cpu_show_common(dev, attr, buf, X86_BUG_ITS); } + +ssize_t cpu_show_tsa(struct device *dev, struct device_attribute *attr, char *buf) +{ + return cpu_show_common(dev, attr, buf, X86_BUG_TSA); +} #endif void __warn_thunk(void) |