diff options
author | H. Peter Anvin <hpa@linux.intel.com> | 2010-09-17 15:39:11 -0700 |
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committer | H. Peter Anvin <hpa@linux.intel.com> | 2010-09-17 15:39:11 -0700 |
commit | ea53069231f9317062910d6e772cca4ce93de8c8 (patch) | |
tree | 0a78cf38c59c92114473925c74a3cf86ed1e543b /arch/x86/include/asm/processor.h | |
parent | bc83cccc761953f878088cdfa682de0970b5561f (diff) |
x86, hotplug: Use mwait to offline a processor, fix the legacy case
The code in native_play_dead() has a number of problems:
1. We should use MWAIT when available, to put ourselves into a deeper
sleep state.
2. We use the existence of CLFLUSH to determine if WBINVD is safe, but
that is totally bogus -- WBINVD is 486+, whereas CLFLUSH is a much
later addition.
3. We should do WBINVD inside the loop, just in case of something like
setting an A bit on page tables. Pointed out by Arjan van de Ven.
This code is based in part of a previous patch by Venki Pallipadi, but
unlike that patch this one keeps all the detection code local instead
of pre-caching a bunch of information. We're shutting down the CPU;
there is absolutely no hurry.
This patch moves all the code to C and deletes the global
wbinvd_halt() which is broken anyway.
Originally-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Venkatesh Pallipadi <venki@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.hl>
LKML-Reference: <20090522232230.162239000@intel.com>
Diffstat (limited to 'arch/x86/include/asm/processor.h')
-rw-r--r-- | arch/x86/include/asm/processor.h | 23 |
1 files changed, 0 insertions, 23 deletions
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 325b7bdbeba..f358241e412 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -764,29 +764,6 @@ extern unsigned long idle_halt; extern unsigned long idle_nomwait; extern bool c1e_detected; -/* - * 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); |