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author | Linus Torvalds <torvalds@linux-foundation.org> | 2010-10-21 13:45:38 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-10-21 13:45:38 -0700 |
commit | 2a8b67fb72c4c4bc15fe8095e3ed613789c8b82f (patch) | |
tree | 1dac291641bc5d0a3acff3d1e48b3328ae54462b /arch/x86/kernel/smpboot.c | |
parent | b6f7e38dbb310557fe890b04b1a376c93f638c3b (diff) | |
parent | ce5f68246bf2385d6174856708d0b746dc378f20 (diff) | |
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Merge branch 'x86-idle-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-idle-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, hotplug: In the MWAIT case of play_dead, CLFLUSH the cache line
x86, hotplug: Move WBINVD back outside the play_dead loop
x86, hotplug: Use mwait to offline a processor, fix the legacy case
x86, mwait: Move mwait constants to a common header file
Diffstat (limited to 'arch/x86/kernel/smpboot.c')
-rw-r--r-- | arch/x86/kernel/smpboot.c | 80 |
1 files changed, 79 insertions, 1 deletions
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index bc2cc44..0116552 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -62,6 +62,7 @@ #include <asm/pgtable.h> #include <asm/tlbflush.h> #include <asm/mtrr.h> +#include <asm/mwait.h> #include <asm/vmi.h> #include <asm/apic.h> #include <asm/setup.h> @@ -1395,11 +1396,88 @@ void play_dead_common(void) local_irq_disable(); } +/* + * 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 */ |