From ea53069231f9317062910d6e772cca4ce93de8c8 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Fri, 17 Sep 2010 15:39:11 -0700 Subject: 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 Signed-off-by: H. Peter Anvin Reviewed-by: Arjan van de Ven Cc: Len Brown Cc: Venkatesh Pallipadi Cc: Peter Zijlstra LKML-Reference: <20090522232230.162239000@intel.com> --- arch/x86/include/asm/processor.h | 23 ----------------------- 1 file changed, 23 deletions(-) (limited to 'arch/x86/include/asm/processor.h') 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); -- cgit v1.2.3-70-g09d2