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authorBoris Ostrovsky <ostr@amd64.org>2011-05-26 11:19:52 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2011-06-23 15:28:35 -0700
commit936107f142c4c05e55de7b1f1c5c049dd0cb91dc (patch)
tree6dd95eae5113ff419db83161f42e266752d7a375
parentaf3834a4ee48dbf533f0e46bb05df60ea2209cb9 (diff)
x86, amd: Do not enable ARAT feature on AMD processors below family 0x12
commit e9cdd343a5e42c43bcda01e609fa23089e026470 upstream. Commit b87cf80af3ba4b4c008b4face3c68d604e1715c6 added support for ARAT (Always Running APIC timer) on AMD processors that are not affected by erratum 400. This erratum is present on certain processor families and prevents APIC timer from waking up the CPU when it is in a deep C state, including C1E state. Determining whether a processor is affected by this erratum may have some corner cases and handling these cases is somewhat complicated. In the interest of simplicity we won't claim ARAT support on processor families below 0x12 and will go back to broadcasting timer when going idle. Signed-off-by: Boris Ostrovsky <ostr@amd64.org> Link: http://lkml.kernel.org/r/1306423192-19774-1-git-send-email-ostr@amd64.org Tested-by: Boris Petkov <borislav.petkov@amd.com> Cc: Hans Rosenfeld <Hans.Rosenfeld@amd.com> Cc: Andreas Herrmann <Andreas.Herrmann3@amd.com> Cc: Chuck Ebbert <cebbert@redhat.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--arch/x86/kernel/cpu/amd.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 38254806bf3..ce87794943f 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -565,8 +565,11 @@ 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))
+ /*
+ * Family 0x12 and above processors have APIC timer
+ * running in deep C states.
+ */
+ if (c->x86 > 0x11)
set_cpu_cap(c, X86_FEATURE_ARAT);
/*