diff options
Diffstat (limited to 'arch/x86/kernel/cpu/intel.c')
| -rw-r--r-- | arch/x86/kernel/cpu/intel.c | 53 |
1 files changed, 45 insertions, 8 deletions
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 1f7fdb91a818..6e2ffbebbcdb 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -25,6 +25,41 @@ #include <asm/apic.h> #endif +/* + * Just in case our CPU detection goes bad, or you have a weird system, + * allow a way to override the automatic disabling of MPX. + */ +static int forcempx; + +static int __init forcempx_setup(char *__unused) +{ + forcempx = 1; + + return 1; +} +__setup("intel-skd-046-workaround=disable", forcempx_setup); + +void check_mpx_erratum(struct cpuinfo_x86 *c) +{ + if (forcempx) + return; + /* + * Turn off the MPX feature on CPUs where SMEP is not + * available or disabled. + * + * Works around Intel Erratum SKD046: "Branch Instructions + * May Initialize MPX Bound Registers Incorrectly". + * + * This might falsely disable MPX on systems without + * SMEP, like Atom processors without SMEP. But there + * is no such hardware known at the moment. + */ + if (cpu_has(c, X86_FEATURE_MPX) && !cpu_has(c, X86_FEATURE_SMEP)) { + setup_clear_cpu_cap(X86_FEATURE_MPX); + pr_warn("x86/mpx: Disabling MPX since SMEP not present\n"); + } +} + static void early_init_intel(struct cpuinfo_x86 *c) { u64 misc_enable; @@ -152,9 +187,9 @@ static void early_init_intel(struct cpuinfo_x86 *c) * the TLB when any changes are made to any of the page table entries. * The operating system must reload CR3 to cause the TLB to be flushed" * - * As a result cpu_has_pge() in arch/x86/include/asm/tlbflush.h should - * be false so that __flush_tlb_all() causes CR3 insted of CR4.PGE - * to be modified + * As a result, boot_cpu_has(X86_FEATURE_PGE) in arch/x86/include/asm/tlbflush.h + * should be false so that __flush_tlb_all() causes CR3 insted of CR4.PGE + * to be modified. */ if (c->x86 == 5 && c->x86_model == 9) { pr_info("Disabling PGE capability bit\n"); @@ -173,6 +208,8 @@ static void early_init_intel(struct cpuinfo_x86 *c) if (edx & (1U << 28)) c->x86_coreid_bits = get_count_order((ebx >> 16) & 0xff); } + + check_mpx_erratum(c); } #ifdef CONFIG_X86_32 @@ -233,7 +270,7 @@ static void intel_workarounds(struct cpuinfo_x86 *c) * The Quark is also family 5, but does not have the same bug. */ clear_cpu_bug(c, X86_BUG_F00F); - if (!paravirt_enabled() && c->x86 == 5 && c->x86_model < 9) { + if (c->x86 == 5 && c->x86_model < 9) { static int f00f_workaround_enabled; set_cpu_bug(c, X86_BUG_F00F); @@ -281,7 +318,7 @@ static void intel_workarounds(struct cpuinfo_x86 *c) * integrated APIC (see 11AP erratum in "Pentium Processor * Specification Update"). */ - if (cpu_has_apic && (c->x86<<8 | c->x86_model<<4) == 0x520 && + if (boot_cpu_has(X86_FEATURE_APIC) && (c->x86<<8 | c->x86_model<<4) == 0x520 && (c->x86_mask < 0x6 || c->x86_mask == 0xb)) set_cpu_bug(c, X86_BUG_11AP); @@ -336,7 +373,7 @@ static int intel_num_cpu_cores(struct cpuinfo_x86 *c) { unsigned int eax, ebx, ecx, edx; - if (c->cpuid_level < 4) + if (!IS_ENABLED(CONFIG_SMP) || c->cpuid_level < 4) return 1; /* Intel has a non-standard dependency on %ecx for this CPUID level. */ @@ -456,7 +493,7 @@ static void init_intel(struct cpuinfo_x86 *c) set_cpu_cap(c, X86_FEATURE_ARCH_PERFMON); } - if (cpu_has_xmm2) + if (cpu_has(c, X86_FEATURE_XMM2)) set_cpu_cap(c, X86_FEATURE_LFENCE_RDTSC); if (boot_cpu_has(X86_FEATURE_DS)) { @@ -468,7 +505,7 @@ static void init_intel(struct cpuinfo_x86 *c) set_cpu_cap(c, X86_FEATURE_PEBS); } - if (c->x86 == 6 && cpu_has_clflush && + if (c->x86 == 6 && boot_cpu_has(X86_FEATURE_CLFLUSH) && (c->x86_model == 29 || c->x86_model == 46 || c->x86_model == 47)) set_cpu_bug(c, X86_BUG_CLFLUSH_MONITOR); |