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authorLinus Torvalds <torvalds@linux-foundation.org>2010-10-21 13:45:38 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-10-21 13:45:38 -0700
commit2a8b67fb72c4c4bc15fe8095e3ed613789c8b82f (patch)
tree1dac291641bc5d0a3acff3d1e48b3328ae54462b /arch
parentb6f7e38dbb310557fe890b04b1a376c93f638c3b (diff)
parentce5f68246bf2385d6174856708d0b746dc378f20 (diff)
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')
-rw-r--r--arch/x86/include/asm/mwait.h15
-rw-r--r--arch/x86/include/asm/processor.h23
-rw-r--r--arch/x86/kernel/acpi/cstate.c11
-rw-r--r--arch/x86/kernel/smpboot.c80
4 files changed, 95 insertions, 34 deletions
diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h
new file mode 100644
index 00000000000..bcdff997668
--- /dev/null
+++ b/arch/x86/include/asm/mwait.h
@@ -0,0 +1,15 @@
+#ifndef _ASM_X86_MWAIT_H
+#define _ASM_X86_MWAIT_H
+
+#define MWAIT_SUBSTATE_MASK 0xf
+#define MWAIT_CSTATE_MASK 0xf
+#define MWAIT_SUBSTATE_SIZE 4
+#define MWAIT_MAX_NUM_CSTATES 8
+
+#define CPUID_MWAIT_LEAF 5
+#define CPUID5_ECX_EXTENSIONS_SUPPORTED 0x1
+#define CPUID5_ECX_INTERRUPT_BREAK 0x2
+
+#define MWAIT_ECX_INTERRUPT_BREAK 0x1
+
+#endif /* _ASM_X86_MWAIT_H */
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index a668d66301f..cae9c3cb95c 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -766,29 +766,6 @@ 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);
diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
index fb16f17e59b..5812404a0d4 100644
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -13,6 +13,7 @@
#include <acpi/processor.h>
#include <asm/acpi.h>
+#include <asm/mwait.h>
/*
* Initialize bm_flags based on the CPU cache properties
@@ -65,16 +66,6 @@ static struct cstate_entry __percpu *cpu_cstate_entry; /* per CPU ptr */
static short mwait_supported[ACPI_PROCESSOR_MAX_POWER];
-#define MWAIT_SUBSTATE_MASK (0xf)
-#define MWAIT_CSTATE_MASK (0xf)
-#define MWAIT_SUBSTATE_SIZE (4)
-
-#define CPUID_MWAIT_LEAF (5)
-#define CPUID5_ECX_EXTENSIONS_SUPPORTED (0x1)
-#define CPUID5_ECX_INTERRUPT_BREAK (0x2)
-
-#define MWAIT_ECX_INTERRUPT_BREAK (0x1)
-
#define NATIVE_CSTATE_BEYOND_HALT (2)
static long acpi_processor_ffh_cstate_probe_cpu(void *_cx)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index bc2cc444844..0116552c950 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(&current_cpu_data, X86_FEATURE_MWAIT))
+ return;
+ if (!cpu_has(&current_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 = &current_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 */