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authorBoris Ostrovsky <boris.ostrovsky@amd.com>2011-03-15 12:13:44 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2011-04-22 08:44:19 -0700
commitd4274252d17368745a550db596607e7233cdc4d0 (patch)
treef81b3376fa9e222b60a9258b40c4a7ef6b03afe6
parent7a3b25c05575f86bf1ba3a397d301752dd981c49 (diff)
downloadlinux-linaro-stable-d4274252d17368745a550db596607e7233cdc4d0.tar.gz
x86, AMD: Set ARAT feature on AMD processors
commit b87cf80af3ba4b4c008b4face3c68d604e1715c6 upstream. Support for Always Running APIC timer (ARAT) was introduced in commit db954b5898dd3ef3ef93f4144158ea8f97deb058. This feature allows us to avoid switching timers from LAPIC to something else (e.g. HPET) and go into timer broadcasts when entering deep C-states. AMD processors don't provide a CPUID bit for that feature but they also keep APIC timers running in deep C-states (except for cases when the processor is affected by erratum 400). Therefore we should set ARAT feature bit on AMD CPUs. Tested-by: Borislav Petkov <borislav.petkov@amd.com> Acked-by: Andreas Herrmann <andreas.herrmann3@amd.com> Acked-by: Mark Langsdorf <mark.langsdorf@amd.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@amd.com> LKML-Reference: <1300205624-4813-1-git-send-email-ostr@amd64.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--arch/x86/kernel/cpu/amd.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 7c92c16bb31d..105c2a7cfe58 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -566,6 +566,10 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c)
}
}
#endif
+
+ /* As a rule processors have APIC timer running in deep C states */
+ if (c->x86 >= 0xf && !cpu_has_amd_erratum(amd_erratum_400))
+ set_cpu_cap(c, X86_FEATURE_ARAT);
}
#ifdef CONFIG_X86_32