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authorAndi Kleen <ak@suse.de>2008-01-30 13:33:16 +0100
committerIngo Molnar <mingo@elte.hu>2008-01-30 13:33:16 +0100
commit0c07ee38c9d4eb081758f5ad14bbffa7197e1aec (patch)
treef32f5dba9b03b9fa5ac262a2c569b43ae9d0994e
parent30d432dfab2bcfd021d352e2058fae6b9405caeb (diff)
x86: use the correct cpuid method to detect MWAIT support for C states
Previously there was a AMD specific quirk to handle the case of AMD Fam10h MWAIT not supporting any C states. But it turns out that CPUID already has ways to detectly detect that without using special quirks. The new code simply checks if MWAIT supports at least C1 and doesn't use it if it doesn't. No more vendor specific code. Note this is does not simply clear MWAIT because MWAIT can be still useful even without C states. Credit goes to Ben Serebrin for pointing out the (nearly) obvious. Cc: "Andreas Herrmann" <andreas.herrmann3@amd.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r--arch/x86/kernel/cpu/amd.c3
-rw-r--r--arch/x86/kernel/process_32.c10
-rw-r--r--arch/x86/kernel/process_64.c11
-rw-r--r--arch/x86/kernel/setup_64.c4
4 files changed, 19 insertions, 9 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index cd2fe15ff4b5..06fa159232fd 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -300,9 +300,6 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c)
local_apic_timer_disabled = 1;
#endif
- if (c->x86 == 0x10 && !force_mwait)
- clear_bit(X86_FEATURE_MWAIT, c->x86_capability);
-
/* K6s reports MCEs but don't actually have all the MSRs */
if (c->x86 < 6)
clear_bit(X86_FEATURE_MCE, c->x86_capability);
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 69a69c3f43bb..9f45a51af968 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -285,9 +285,17 @@ static void mwait_idle(void)
mwait_idle_with_hints(0, 0);
}
+static int mwait_usable(const struct cpuinfo_x86 *c)
+{
+ if (force_mwait)
+ return 1;
+ /* Any C1 states supported? */
+ return c->cpuid_level >= 5 && ((cpuid_edx(5) >> 4) & 0xf) > 0;
+}
+
void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
{
- if (cpu_has(c, X86_FEATURE_MWAIT)) {
+ if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
printk("monitor/mwait feature present.\n");
/*
* Skip, if setup has overridden idle.
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 4e65ae8a54bf..dbe0a846ec52 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -280,10 +280,19 @@ static void mwait_idle(void)
}
}
+
+static int mwait_usable(const struct cpuinfo_x86 *c)
+{
+ if (force_mwait)
+ return 1;
+ /* Any C1 states supported? */
+ return c->cpuid_level >= 5 && ((cpuid_edx(5) >> 4) & 0xf) > 0;
+}
+
void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
{
static int printed;
- if (cpu_has(c, X86_FEATURE_MWAIT)) {
+ if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
/*
* Skip, if setup has overridden idle.
* One CPU supports mwait => All CPUs supports mwait
diff --git a/arch/x86/kernel/setup_64.c b/arch/x86/kernel/setup_64.c
index 71a420c7fee7..4a3f00b49236 100644
--- a/arch/x86/kernel/setup_64.c
+++ b/arch/x86/kernel/setup_64.c
@@ -761,10 +761,6 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c)
/* MFENCE stops RDTSC speculation */
set_cpu_cap(c, X86_FEATURE_MFENCE_RDTSC);
- /* Family 10 doesn't support C states in MWAIT so don't use it */
- if (c->x86 == 0x10 && !force_mwait)
- clear_cpu_cap(c, X86_FEATURE_MWAIT);
-
if (amd_apic_timer_broken())
disable_apic_timer = 1;
}