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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 08:50:00 -0700
commit747e6c273ba60048de77189553efdc3caa9b1b06 (patch)
tree4684d89a3744fcdef98448b84c05664a3042e190
parent165ed2c6017e420a5b640b918162b7729c5ef3ab (diff)
downloadlinux-linaro-stable-747e6c273ba60048de77189553efdc3caa9b1b06.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 d11629a89b03..31e2b8546764 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -564,6 +564,10 @@ 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