Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752044AbXAROjM (ORCPT ); Thu, 18 Jan 2007 09:39:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752047AbXAROjM (ORCPT ); Thu, 18 Jan 2007 09:39:12 -0500 Received: from mailhub.sw.ru ([195.214.233.200]:45440 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752044AbXAROjL (ORCPT ); Thu, 18 Jan 2007 09:39:11 -0500 Date: Thu, 18 Jan 2007 17:45:27 +0300 From: Alexey Dobriyan To: ak@suse.de, akpm@osdl.org Cc: linux-kernel@vger.kernel.org, davej@codemonkey.org.uk, devel@vger.kernel.org Subject: [PATCH] rdmsr_on_cpu, wrmsr_on_cpu Message-ID: <20070118144527.GA6021@localhost.sw.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5742 Lines: 201 There was OpenVZ specific bug rendering some cpufreq drivers unusable on SMP. In short, when cpufreq code thinks it confined itself to needed cpu by means of set_cpus_allowed() to execute rdmsr, some "virtual cpu" feature can migrate process to anywhere. This triggers bugons and does wrong things in general. This got fixed by introducing rdmsr_on_cpu and wrmsr_on_cpu executing rdmsr and wrmsr on given physical cpu by means of smp_call_function_single(). Dave Jones mentioned cpufreq might be not only user of rdmsr_on_cpu() and wrmsr_on_cpu(), so I'm going to put them into arch/i386/lib/ (after patch gets some more testing othen than compile and UP run) Does this looks OK? arch/i386/kernel/cpu/cpufreq/p4-clockmod.c | 30 ++---------- arch/i386/lib/Makefile | 2 arch/i386/lib/msr-on-cpu.c | 70 +++++++++++++++++++++++++++++ include/asm-i386/msr.h | 3 + 4 files changed, 81 insertions(+), 24 deletions(-) --- a/arch/i386/lib/Makefile +++ b/arch/i386/lib/Makefile @@ -7,3 +7,5 @@ lib-y = checksum.o delay.o usercopy.o ge bitops.o semaphore.o lib-$(CONFIG_X86_USE_3DNOW) += mmx.o + +obj-y = msr-on-cpu.o --- /dev/null +++ b/arch/i386/lib/msr-on-cpu.c @@ -0,0 +1,70 @@ +#include +#include +#include +#include + +#ifdef CONFIG_SMP +struct msr_info { + u32 msr_no; + u32 l, h; +}; + +static void __rdmsr_on_cpu(void *info) +{ + struct msr_info *rv = info; + + rdmsr(rv->msr_no, rv->l, rv->h); +} + +void rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h) +{ + preempt_disable(); + if (smp_processor_id() == cpu) + rdmsr(msr_no, *l, *h); + else { + struct msr_info rv; + + rv.msr_no = msr_no; + smp_call_function_single(cpu, __rdmsr_on_cpu, &rv, 0, 1); + *l = rv.l; + *h = rv.h; + } + preempt_enable(); +} + +static void __wrmsr_on_cpu(void *info) +{ + struct msr_info *rv = info; + + wrmsr(rv->msr_no, rv->l, rv->h); +} + +void wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h) +{ + preempt_disable(); + if (smp_processor_id() == cpu) + wrmsr(msr_no, l, h); + else { + struct msr_info rv; + + rv.msr_no = msr_no; + rv.l = l; + rv.h = h; + smp_call_function_single(cpu, __wrmsr_on_cpu, &rv, 0, 1); + } + preempt_enable(); +} +#else +void rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h) +{ + rdmsr(msr_no, *l, *h); +} + +void wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h) +{ + wrmsr(msr_no, l, h); +} +#endif + +EXPORT_SYMBOL(rdmsr_on_cpu); +EXPORT_SYMBOL(wrmsr_on_cpu); --- a/include/asm-i386/msr.h +++ b/include/asm-i386/msr.h @@ -83,6 +83,9 @@ #define rdpmc(counter,low,high) \ : "c" (counter)) #endif /* !CONFIG_PARAVIRT */ +void rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h); +void wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h); + /* symbolic names for some interesting MSRs */ /* Intel defined MSRs. */ #define MSR_IA32_P5_MC_ADDR 0 --- a/arch/i386/kernel/cpu/cpufreq/p4-clockmod.c +++ b/arch/i386/kernel/cpu/cpufreq/p4-clockmod.c @@ -63,7 +63,7 @@ static int cpufreq_p4_setdc(unsigned int if (!cpu_online(cpu) || (newstate > DC_DISABLE) || (newstate == DC_RESV)) return -EINVAL; - rdmsr(MSR_IA32_THERM_STATUS, l, h); + rdmsr_on_cpu(cpu, MSR_IA32_THERM_STATUS, &l, &h); if (l & 0x01) dprintk("CPU#%d currently thermal throttled\n", cpu); @@ -71,10 +71,10 @@ static int cpufreq_p4_setdc(unsigned int if (has_N44_O17_errata[cpu] && (newstate == DC_25PT || newstate == DC_DFLT)) newstate = DC_38PT; - rdmsr(MSR_IA32_THERM_CONTROL, l, h); + rdmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, &l, &h); if (newstate == DC_DISABLE) { dprintk("CPU#%d disabling modulation\n", cpu); - wrmsr(MSR_IA32_THERM_CONTROL, l & ~(1<<4), h); + wrmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, l & ~(1<<4), h); } else { dprintk("CPU#%d setting duty cycle to %d%%\n", cpu, ((125 * newstate) / 10)); @@ -85,7 +85,7 @@ static int cpufreq_p4_setdc(unsigned int */ l = (l & ~14); l = l | (1<<4) | ((newstate & 0x7)<<1); - wrmsr(MSR_IA32_THERM_CONTROL, l, h); + wrmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, l, h); } return 0; @@ -112,7 +112,6 @@ static int cpufreq_p4_target(struct cpuf { unsigned int newstate = DC_RESV; struct cpufreq_freqs freqs; - cpumask_t cpus_allowed; int i; if (cpufreq_frequency_table_target(policy, &p4clockmod_table[0], target_freq, relation, &newstate)) @@ -133,17 +132,8 @@ static int cpufreq_p4_target(struct cpuf /* run on each logical CPU, see section 13.15.3 of IA32 Intel Architecture Software * Developer's Manual, Volume 3 */ - cpus_allowed = current->cpus_allowed; - - for_each_cpu_mask(i, policy->cpus) { - cpumask_t this_cpu = cpumask_of_cpu(i); - - set_cpus_allowed(current, this_cpu); - BUG_ON(smp_processor_id() != i); - + for_each_cpu_mask(i, policy->cpus) cpufreq_p4_setdc(i, p4clockmod_table[newstate].index); - } - set_cpus_allowed(current, cpus_allowed); /* notifiers */ for_each_cpu_mask(i, policy->cpus) { @@ -265,17 +255,9 @@ static int cpufreq_p4_cpu_exit(struct cp static unsigned int cpufreq_p4_get(unsigned int cpu) { - cpumask_t cpus_allowed; u32 l, h; - cpus_allowed = current->cpus_allowed; - - set_cpus_allowed(current, cpumask_of_cpu(cpu)); - BUG_ON(smp_processor_id() != cpu); - - rdmsr(MSR_IA32_THERM_CONTROL, l, h); - - set_cpus_allowed(current, cpus_allowed); + rdmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, &l, &h); if (l & 0x10) { l = l >> 1; - 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/