x86 idle: remove 32-bit-only "no-hlt" parameter, hlt_works_ok flag

Remove 32-bit x86 a cmdline param "no-hlt",
and the cpuinfo_x86.hlt_works_ok that it sets.

If a user wants to avoid HLT, then "idle=poll"
is much more useful, as it avoids invocation of HLT
in idle, while "no-hlt" failed to do so.

Indeed, hlt_works_ok was consulted in only 3 places.

First, in /proc/cpuinfo where "hlt_bug yes"
would be printed if and only if the user booted
the system with "no-hlt" -- as there was no other code
to set that flag.

Second, check_hlt() would not invoke halt() if "no-hlt"
were on the cmdline.

Third, it was consulted in stop_this_cpu(), which is invoked
by native_machine_halt()/reboot_interrupt()/smp_stop_nmi_callback() --
all cases where the machine is being shutdown/reset.
The flag was not consulted in the more frequently invoked
play_dead()/hlt_play_dead() used in processor offline and suspend.

Since Linux-3.0 there has been a run-time notice upon "no-hlt" invocations
indicating that it would be removed in 2012.

Signed-off-by: Len Brown <len.brown@intel.com>
Cc: x86@kernel.org

6 files changed, 2 insertions, 50 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 3b0cd1e612da..109ee45cf20d 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1881,10 +1881,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                         wfi(ARM) instruction doesn't work correctly and not to
                         use it. This is also useful when using JTAG debugger.
 
-        no-hlt          [BUGS=X86-32] Tells the kernel that the hlt
-                        instruction doesn't work correctly and not to
-                        use it.
-
         no_file_caps    Tells the kernel not to honor file capabilities.  The
                         only way then for a file to be executed with privilege
                         is to be setuid root or executed by root.
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 8a28feae1c92..b9e7d279f8ef 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -89,7 +89,6 @@ struct cpuinfo_x86 {
         char                    wp_works_ok;    /* It doesn't on 386's */
 
         /* Problems on some 486Dx4's and old 386's: */
-        char                    hlt_works_ok;
         char                    hard_math;
         char                    rfu;
         char                    fdiv_bug;
@@ -165,15 +164,6 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct cpuinfo_x86, cpu_info);
 
 extern const struct seq_operations cpuinfo_op;
 
-static inline int hlt_works(int cpu)
-{
-#ifdef CONFIG_X86_32
-        return cpu_data(cpu).hlt_works_ok;
-#else
-        return 1;
-#endif
-}
-
 #define cache_line_size()       (boot_cpu_data.x86_cache_alignment)
 
 extern void cpu_detect(struct cpuinfo_x86 *c);
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 92dfec986a48..af6455e3fcc9 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -17,15 +17,6 @@
 #include <asm/paravirt.h>
 #include <asm/alternative.h>
 
-static int __init no_halt(char *s)
-{
-        WARN_ONCE(1, "\"no-hlt\" is deprecated, please use \"idle=poll\"\n");
-        boot_cpu_data.hlt_works_ok = 0;
-        return 1;
-}
-
-__setup("no-hlt", no_halt);
-
 static int __init no_387(char *s)
 {
         boot_cpu_data.hard_math = 0;
@@ -89,23 +80,6 @@ static void __init check_fpu(void)
                 pr_warn("Hmm, FPU with FDIV bug\n");
 }
 
-static void __init check_hlt(void)
-{
-        if (boot_cpu_data.x86 >= 5 || paravirt_enabled())
-                return;
-
-        pr_info("Checking 'hlt' instruction... ");
-        if (!boot_cpu_data.hlt_works_ok) {
-                pr_cont("disabled\n");
-                return;
-        }
-        halt();
-        halt();
-        halt();
-        halt();
-        pr_cont("OK\n");
-}
-
 /*
  * Check whether we are able to run this kernel safely on SMP.
  *
@@ -129,7 +103,6 @@ void __init check_bugs(void)
         print_cpu_info(&boot_cpu_data);
 #endif
         check_config();
-        check_hlt();
         init_utsname()->machine[1] =
                 '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
         alternative_instructions();
diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
index 3286a92e662a..e280253f6f94 100644
--- a/arch/x86/kernel/cpu/proc.c
+++ b/arch/x86/kernel/cpu/proc.c
@@ -28,7 +28,6 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
 {
         seq_printf(m,
                    "fdiv_bug\t: %s\n"
-                   "hlt_bug\t\t: %s\n"
                    "f00f_bug\t: %s\n"
                    "coma_bug\t: %s\n"
                    "fpu\t\t: %s\n"
@@ -36,7 +35,6 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
                    "cpuid level\t: %d\n"
                    "wp\t\t: %s\n",
                    c->fdiv_bug ? "yes" : "no",
-                   c->hlt_works_ok ? "no" : "yes",
                    c->f00f_bug ? "yes" : "no",
                    c->coma_bug ? "yes" : "no",
                    c->hard_math ? "yes" : "no",
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index cd5a4c9ef835..aef852eac292 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -415,10 +415,8 @@ void stop_this_cpu(void *dummy)
         set_cpu_online(smp_processor_id(), false);
         disable_local_APIC();
 
-        for (;;) {
-                if (hlt_works(smp_processor_id()))
-                        halt();
-        }
+        for (;;)
+                halt();
 }
 
 /*
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 2b73b5c8555f..94eac5c85cdc 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -556,9 +556,6 @@ void __init xen_arch_setup(void)
                COMMAND_LINE_SIZE : MAX_GUEST_CMDLINE);
 
         /* Set up idle, making sure it calls safe_halt() pvop */
-#ifdef CONFIG_X86_32
-        boot_cpu_data.hlt_works_ok = 1;
-#endif
         disable_cpuidle();
         disable_cpufreq();
         WARN_ON(xen_set_default_idle());