Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754832Ab1DSUR3 (ORCPT ); Tue, 19 Apr 2011 16:17:29 -0400 Received: from kroah.org ([198.145.64.141]:35604 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754769Ab1DSURY (ORCPT ); Tue, 19 Apr 2011 16:17:24 -0400 X-Mailbox-Line: From gregkh@clark.kroah.org Tue Apr 19 13:10:47 2011 Message-Id: <20110419201047.560550482@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Tue, 19 Apr 2011 13:08:50 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Andreas Herrmann , Mark Langsdorf , Thomas Gleixner , Boris Ostrovsky , Ingo Molnar Subject: [41/70] x86, AMD: Set ARAT feature on AMD processors In-Reply-To: <20110419201501.GA8865@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1792 Lines: 52 2.6.38-stable review patch. If anyone has any objections, please let us know. ------------------ From: Boris Ostrovsky 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 Acked-by: Andreas Herrmann Acked-by: Mark Langsdorf Acked-by: Thomas Gleixner Signed-off-by: Boris Ostrovsky LKML-Reference: <1300205624-4813-1-git-send-email-ostr@amd64.org> Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/amd.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -594,6 +594,10 @@ static void __cpuinit init_amd(struct cp } } #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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/