diff options
Diffstat (limited to 'arch/x86/kernel/cpu/bugs.c')
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 405a9a61bb89..27830880e7a7 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -22,15 +22,18 @@ #include <asm/processor-flags.h> #include <asm/fpu/internal.h> #include <asm/msr.h> +#include <asm/vmx.h> #include <asm/paravirt.h> #include <asm/alternative.h> #include <asm/pgtable.h> #include <asm/set_memory.h> #include <asm/intel-family.h> +#include <asm/e820/api.h> #include <asm/hypervisor.h> 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 @@ -56,6 +59,12 @@ void __init check_bugs(void) { identify_boot_cpu(); + /* + * identify_boot_cpu() initialized SMT support information, let the + * core code know. + */ + cpu_smt_check_topology_early(); + if (!IS_ENABLED(CONFIG_SMP)) { pr_info("CPU: "); print_cpu_info(&boot_cpu_data); @@ -82,6 +91,8 @@ void __init check_bugs(void) */ ssb_select_mitigation(); + l1tf_select_mitigation(); + #ifdef CONFIG_X86_32 /* * Check whether we are able to run this kernel safely on SMP. @@ -646,8 +657,121 @@ void x86_spec_ctrl_setup_ap(void) x86_amd_ssb_disable(); } +#undef pr_fmt +#define pr_fmt(fmt) "L1TF: " fmt + +/* Default mitigation for L1TF-affected CPUs */ +enum l1tf_mitigations l1tf_mitigation __ro_after_init = L1TF_MITIGATION_FLUSH; +#if IS_ENABLED(CONFIG_KVM_INTEL) +EXPORT_SYMBOL_GPL(l1tf_mitigation); + +enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO; +EXPORT_SYMBOL_GPL(l1tf_vmx_mitigation); +#endif + +static void __init l1tf_select_mitigation(void) +{ + u64 half_pa; + + if (!boot_cpu_has_bug(X86_BUG_L1TF)) + return; + + switch (l1tf_mitigation) { + case L1TF_MITIGATION_OFF: + case L1TF_MITIGATION_FLUSH_NOWARN: + case L1TF_MITIGATION_FLUSH: + break; + case L1TF_MITIGATION_FLUSH_NOSMT: + case L1TF_MITIGATION_FULL: + cpu_smt_disable(false); + break; + case L1TF_MITIGATION_FULL_FORCE: + cpu_smt_disable(true); + break; + } + +#if CONFIG_PGTABLE_LEVELS == 2 + pr_warn("Kernel not compiled for PAE. No mitigation for L1TF\n"); + return; +#endif + + /* + * This is extremely unlikely to happen because almost all + * systems have far more MAX_PA/2 than RAM can be fit into + * DIMM slots. + */ + half_pa = (u64)l1tf_pfn_limit() << PAGE_SHIFT; + if (e820__mapped_any(half_pa, ULLONG_MAX - half_pa, E820_TYPE_RAM)) { + pr_warn("System has more than MAX_PA/2 memory. L1TF mitigation not effective.\n"); + return; + } + + setup_force_cpu_cap(X86_FEATURE_L1TF_PTEINV); +} + +static int __init l1tf_cmdline(char *str) +{ + if (!boot_cpu_has_bug(X86_BUG_L1TF)) + return 0; + + if (!str) + return -EINVAL; + + if (!strcmp(str, "off")) + l1tf_mitigation = L1TF_MITIGATION_OFF; + else if (!strcmp(str, "flush,nowarn")) + l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOWARN; + else if (!strcmp(str, "flush")) + l1tf_mitigation = L1TF_MITIGATION_FLUSH; + else if (!strcmp(str, "flush,nosmt")) + l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT; + else if (!strcmp(str, "full")) + l1tf_mitigation = L1TF_MITIGATION_FULL; + else if (!strcmp(str, "full,force")) + l1tf_mitigation = L1TF_MITIGATION_FULL_FORCE; + + return 0; +} +early_param("l1tf", l1tf_cmdline); + +#undef pr_fmt + #ifdef CONFIG_SYSFS +#define L1TF_DEFAULT_MSG "Mitigation: PTE Inversion" + +#if IS_ENABLED(CONFIG_KVM_INTEL) +static const char *l1tf_vmx_states[] = { + [VMENTER_L1D_FLUSH_AUTO] = "auto", + [VMENTER_L1D_FLUSH_NEVER] = "vulnerable", + [VMENTER_L1D_FLUSH_COND] = "conditional cache flushes", + [VMENTER_L1D_FLUSH_ALWAYS] = "cache flushes", + [VMENTER_L1D_FLUSH_EPT_DISABLED] = "EPT disabled", + [VMENTER_L1D_FLUSH_NOT_REQUIRED] = "flush not necessary" +}; + +static ssize_t l1tf_show_state(char *buf) +{ + if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_AUTO) + return sprintf(buf, "%s\n", L1TF_DEFAULT_MSG); + + if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_EPT_DISABLED || + (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_NEVER && + cpu_smt_control == CPU_SMT_ENABLED)) + return sprintf(buf, "%s; VMX: %s\n", L1TF_DEFAULT_MSG, + l1tf_vmx_states[l1tf_vmx_mitigation]); + + return sprintf(buf, "%s; VMX: %s, SMT %s\n", L1TF_DEFAULT_MSG, + l1tf_vmx_states[l1tf_vmx_mitigation], + cpu_smt_control == CPU_SMT_ENABLED ? "vulnerable" : "disabled"); +} +#else +static ssize_t l1tf_show_state(char *buf) +{ + return sprintf(buf, "%s\n", L1TF_DEFAULT_MSG); +} +#endif + static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr, char *buf, unsigned int bug) { @@ -676,6 +800,10 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr case X86_BUG_SPEC_STORE_BYPASS: return sprintf(buf, "%s\n", ssb_strings[ssb_mode]); + case X86_BUG_L1TF: + if (boot_cpu_has(X86_FEATURE_L1TF_PTEINV)) + return l1tf_show_state(buf); + break; default: break; } @@ -702,4 +830,9 @@ ssize_t cpu_show_spec_store_bypass(struct device *dev, struct device_attribute * { return cpu_show_common(dev, attr, buf, X86_BUG_SPEC_STORE_BYPASS); } + +ssize_t cpu_show_l1tf(struct device *dev, struct device_attribute *attr, char *buf) +{ + return cpu_show_common(dev, attr, buf, X86_BUG_L1TF); +} #endif |