--- arch/x86/kernel/smpboot.c
+++ 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 */
projects / ziggy471-frankenstein-kernel.git / blobdiff