From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754150Ab3LNRbX (ORCPT ); Sat, 14 Dec 2013 12:31:23 -0500 Received: from mail-pd0-f177.google.com ([209.85.192.177]:33843 "EHLO mail-pd0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753901Ab3LNRap (ORCPT ); Sat, 14 Dec 2013 12:30:45 -0500 From: Guenter Roeck To: Arnd Bergmann , Greg Kroah-Hartman Cc: Andrew Morton , lm-sensors@lm-sensors.org, linux-kernel@vger.kernel.org, Guenter Roeck , Jean Delvare Subject: [PATCH 08/14] i8k: Force SMM to run on CPU 0 Date: Sat, 14 Dec 2013 09:30:15 -0800 Message-Id: <1387042221-3671-9-git-send-email-linux@roeck-us.net> X-Mailer: git-send-email 1.7.9.7 In-Reply-To: <1387042221-3671-1-git-send-email-linux@roeck-us.net> References: <1387042221-3671-1-git-send-email-linux@roeck-us.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Studio 1555 with dual-core CPU, reading sensor attributes exported by this driver resulted in random failures combined with system hangups and forced logouts. Information in drivers/firmware/dcdbas.c suggests that SMM accesses must run on CPU 0. With this patch, the problems are gone, suggesting that this is in fact the case. Code derived from drivers/firmware/dcdbas.c. Cc: Jean Delvare Signed-off-by: Guenter Roeck --- drivers/char/i8k.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/drivers/char/i8k.c b/drivers/char/i8k.c index ad0acef..264be2b 100644 --- a/drivers/char/i8k.c +++ b/drivers/char/i8k.c @@ -31,6 +31,7 @@ #include #include #include +#include #include @@ -130,6 +131,17 @@ static int i8k_smm(struct smm_regs *regs) { int rc; int eax = regs->eax; + cpumask_var_t old_mask; + + /* SMM requires CPU 0 */ + if (!alloc_cpumask_var(&old_mask, GFP_KERNEL)) + return -ENOMEM; + cpumask_copy(old_mask, ¤t->cpus_allowed); + set_cpus_allowed_ptr(current, cpumask_of(0)); + if (smp_processor_id() != 0) { + rc = -EBUSY; + goto out; + } #if defined(CONFIG_X86_64) asm volatile("pushq %%rax\n\t" @@ -185,9 +197,12 @@ static int i8k_smm(struct smm_regs *regs) : "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory"); #endif if (rc != 0 || (regs->eax & 0xffff) == 0xffff || regs->eax == eax) - return -EINVAL; + rc = -EINVAL; - return 0; +out: + set_cpus_allowed_ptr(current, old_mask); + free_cpumask_var(old_mask); + return rc; } /* -- 1.7.9.7