From b077ffb3b767c3efb44d00b998385a9cb127255c Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Fri, 16 Feb 2007 01:48:11 -0800 Subject: rdmsr_on_cpu, wrmsr_on_cpu 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 putting them into arch/{i386,x86_64}/lib/ . Signed-off-by: Alexey Dobriyan Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Dave Jones --- include/asm-x86_64/msr.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/asm-x86_64') diff --git a/include/asm-x86_64/msr.h b/include/asm-x86_64/msr.h index 3227bc93d69..995a2b5fb26 100644 --- a/include/asm-x86_64/msr.h +++ b/include/asm-x86_64/msr.h @@ -160,6 +160,8 @@ static inline unsigned int cpuid_edx(unsigned int op) #define MSR_IA32_UCODE_WRITE 0x79 #define MSR_IA32_UCODE_REV 0x8b +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); #endif -- cgit v1.2.3