diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/processor.h | 23 | ||||
| -rw-r--r-- | arch/x86/kernel/smpboot.c | 85 |
2 files changed, 84 insertions, 24 deletions
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 13b1885fe27..78bb4d74292 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -765,29 +765,6 @@ extern unsigned long boot_option_idle_override; extern unsigned long idle_halt; extern unsigned long idle_nomwait; -/* - * on systems with caches, caches must be flashed as the absolute - * last instruction before going into a suspended halt. Otherwise, - * dirty data can linger in the cache and become stale on resume, - * leading to strange errors. - * - * perform a variety of operations to guarantee that the compiler - * will not reorder instructions. wbinvd itself is serializing - * so the processor will not reorder. - * - * Systems without cache can just go into halt. - */ -static inline void wbinvd_halt(void) -{ - mb(); - /* check for clflush to determine if wbinvd is legal */ - if (cpu_has_clflush) - asm volatile("cli; wbinvd; 1: hlt; jmp 1b" : : : "memory"); - else - while (1) - halt(); -} - extern void enable_sep_cpu(void); extern int sysenter_setup(void); diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 7e8e905e2cc..539bb6cacf5 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1338,11 +1338,94 @@ void play_dead_common(void) local_irq_disable(); } +#define MWAIT_SUBSTATE_MASK 0xf +#define MWAIT_SUBSTATE_SIZE 4 + +#define CPUID_MWAIT_LEAF 5 +#define CPUID5_ECX_EXTENSIONS_SUPPORTED 0x1 + +/* + * We need to flush the caches before going to sleep, lest we have + * dirty data in our caches when we come back up. + */ +static inline void mwait_play_dead(void) +{ + unsigned int eax, ebx, ecx, edx; + unsigned int highest_cstate = 0; + unsigned int highest_subcstate = 0; + int i; + void *mwait_ptr; + + if (!cpu_has(¤t_cpu_data, X86_FEATURE_MWAIT)) + return; + if (!cpu_has(¤t_cpu_data, X86_FEATURE_CLFLSH)) + return; + if (current_cpu_data.cpuid_level < CPUID_MWAIT_LEAF) + return; + + eax = CPUID_MWAIT_LEAF; + ecx = 0; + native_cpuid(&eax, &ebx, &ecx, &edx); + + /* + * eax will be 0 if EDX enumeration is not valid. + * Initialized below to cstate, sub_cstate value when EDX is valid. + */ + if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED)) { + eax = 0; + } else { + edx >>= MWAIT_SUBSTATE_SIZE; + for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) { + if (edx & MWAIT_SUBSTATE_MASK) { + highest_cstate = i; + highest_subcstate = edx & MWAIT_SUBSTATE_MASK; + } + } + eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) | + (highest_subcstate - 1); + } + + /* + * This should be a memory location in a cache line which is + * unlikely to be touched by other processors. The actual + * content is immaterial as it is not actually modified in any way. + */ + mwait_ptr = ¤t_thread_info()->flags; + + wbinvd(); + + while (1) { + /* + * The CLFLUSH is a workaround for erratum AAI65 for + * the Xeon 7400 series. It's not clear it is actually + * needed, but it should be harmless in either case. + * The WBINVD is insufficient due to the spurious-wakeup + * case where we return around the loop. + */ + clflush(mwait_ptr); + __monitor(mwait_ptr, 0, 0); + mb(); + __mwait(eax, 0); + } +} + +static inline void hlt_play_dead(void) +{ + if (current_cpu_data.x86 >= 4) + wbinvd(); + + while (1) { + native_halt(); + } +} + void native_play_dead(void) { play_dead_common(); tboot_shutdown(TB_SHUTDOWN_WFS); - wbinvd_halt(); + + mwait_play_dead(); /* Only returns on failure */ + hlt_play_dead(); } #else /* ... !CONFIG_HOTPLUG_CPU */ |