diff options
Diffstat (limited to 'arch/x86/kernel/cpu/common.c')
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 39 |
1 files changed, 29 insertions, 10 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 02d97834a1d4..e7ab22fce3b5 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -7,6 +7,7 @@ #include <linux/bitops.h> #include <linux/kernel.h> #include <linux/export.h> +#include <linux/kvm_types.h> #include <linux/percpu.h> #include <linux/string.h> #include <linux/ctype.h> @@ -405,6 +406,28 @@ out: cr4_clear_bits(X86_CR4_UMIP); } +static __always_inline void setup_lass(struct cpuinfo_x86 *c) +{ + if (!cpu_feature_enabled(X86_FEATURE_LASS)) + return; + + /* + * Legacy vsyscall page access causes a #GP when LASS is active. + * Disable LASS because the #GP handler doesn't support vsyscall + * emulation. + * + * Also disable LASS when running under EFI, as some runtime and + * boot services rely on 1:1 mappings in the lower half. + */ + if (IS_ENABLED(CONFIG_X86_VSYSCALL_EMULATION) || + IS_ENABLED(CONFIG_EFI)) { + setup_clear_cpu_cap(X86_FEATURE_LASS); + return; + } + + cr4_set_bits(X86_CR4_LASS); +} + /* These bits should not change their value after CPU init is finished. */ static const unsigned long cr4_pinned_mask = X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_UMIP | X86_CR4_FSGSBASE | X86_CR4_CET | X86_CR4_FRED; @@ -464,14 +487,14 @@ void cr4_update_irqsoff(unsigned long set, unsigned long clear) __write_cr4(newval); } } -EXPORT_SYMBOL(cr4_update_irqsoff); +EXPORT_SYMBOL_FOR_KVM(cr4_update_irqsoff); /* Read the CR4 shadow. */ unsigned long cr4_read_shadow(void) { return this_cpu_read(cpu_tlbstate.cr4); } -EXPORT_SYMBOL_GPL(cr4_read_shadow); +EXPORT_SYMBOL_FOR_KVM(cr4_read_shadow); void cr4_init(void) { @@ -726,7 +749,7 @@ void load_direct_gdt(int cpu) gdt_descr.size = GDT_SIZE - 1; load_gdt(&gdt_descr); } -EXPORT_SYMBOL_GPL(load_direct_gdt); +EXPORT_SYMBOL_FOR_KVM(load_direct_gdt); /* Load a fixmap remapping of the per-cpu GDT */ void load_fixmap_gdt(int cpu) @@ -1025,12 +1048,8 @@ void get_cpu_cap(struct cpuinfo_x86 *c) c->x86_capability[CPUID_8000_0001_EDX] = edx; } - if (c->extended_cpuid_level >= 0x80000007) { - cpuid(0x80000007, &eax, &ebx, &ecx, &edx); - - c->x86_capability[CPUID_8000_0007_EBX] = ebx; - c->x86_power = edx; - } + if (c->extended_cpuid_level >= 0x80000007) + c->x86_power = cpuid_edx(0x80000007); if (c->extended_cpuid_level >= 0x80000008) { cpuid(0x80000008, &eax, &ebx, &ecx, &edx); @@ -2015,10 +2034,10 @@ static void identify_cpu(struct cpuinfo_x86 *c) /* Disable the PN if appropriate */ squash_the_stupid_serial_number(c); - /* Set up SMEP/SMAP/UMIP */ setup_smep(c); setup_smap(c); setup_umip(c); + setup_lass(c); /* Enable FSGSBASE instructions if available. */ if (cpu_has(c, X86_FEATURE_FSGSBASE)) { |