Re: 2.6.35-rc1 regression with pvclock and smp guests

[Michael Tokarev <mjt@tls.msk.ru>]

Ping? ;)

28.09.2010 15:16, Michael Tokarev wrote:
> Arjan Koers <0h61vkll2ly8 <at> xutrox.com> writes:
> 
>> Move a printk that's using the clock before it's ready
>>
>> Fix a hang during SMP kernel boot on KVM that showed up
>> after commit 489fb490dbf8dab0249ad82b56688ae3842a79e8
>> (2.6.35) and 59aab522154a2f17b25335b63c1cf68a51fb6ae0
>> (2.6.34.1). The problem only occurs when
>> CONFIG_PRINTK_TIME is set.
>>
>> Signed-off-by: Arjan Koers <0h61vkll2ly8 <at> xutrox.com>
>>
>> diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
>> index feaeb0d..71bf2df 100644
>> --- a/arch/x86/kernel/kvmclock.c
>> +++ b/arch/x86/kernel/kvmclock.c
>> @@ -125,12 +125,15 @@ static struct clocksource kvm_clock = {
>>  static int kvm_register_clock(char *txt)
>>  {
>>  	int cpu = smp_processor_id();
>> -	int low, high;
>> +	int low, high, ret;
>> +
>>  	low = (int)__pa(&per_cpu(hv_clock, cpu)) | 1;
>>  	high = ((u64)__pa(&per_cpu(hv_clock, cpu)) >> 32);
>> +	ret = native_write_msr_safe(MSR_KVM_SYSTEM_TIME, low, high);
>>  	printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n",
>>  	       cpu, high, low, txt);
>> -	return native_write_msr_safe(MSR_KVM_SYSTEM_TIME, low, high);
>> +
>> +	return ret;
>>  }
>>
>>  #ifdef CONFIG_X86_LOCAL_APIC
> 
> Folks, should this be sent to -stable kernel?  It is not in any
> upstream kernel as far as I can see (not in linus tree too), but
> this is quite an issue and is hitting people....
> 
> The discussion were stalled quite a while ago too -- this email has
> Date: Mon, 02 Aug 2010 23:35:28 +0200.
> 
> Thanks!
> 
> /mjt