Re: [PATCH v7 06/11] pvqspinlock, x86: Allow unfair queue spinlock in a KVM guest

[Waiman Long <waiman.long@hp.com>]

On 03/20/2014 06:01 PM, Paolo Bonzini wrote:
> Il 19/03/2014 21:14, Waiman Long ha scritto:
>> This patch adds a KVM init function to activate the unfair queue
>> spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config
>> option is selected.
>>
>> Signed-off-by: Waiman Long <Waiman.Long@hp.com>
>> ---
>>  arch/x86/kernel/kvm.c |   17 +++++++++++++++++
>>  1 files changed, 17 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
>> index 713f1b3..a489140 100644
>> --- a/arch/x86/kernel/kvm.c
>> +++ b/arch/x86/kernel/kvm.c
>> @@ -826,3 +826,20 @@ static __init int kvm_spinlock_init_jump(void)
>>  early_initcall(kvm_spinlock_init_jump);
>>
>>  #endif    /* CONFIG_PARAVIRT_SPINLOCKS */
>> +
>> +#ifdef CONFIG_PARAVIRT_UNFAIR_LOCKS
>> +/*
>> + * Enable unfair lock if running in a real para-virtualized environment
>> + */
>> +static __init int kvm_unfair_locks_init_jump(void)
>> +{
>> +    if (!kvm_para_available())
>> +        return 0;
>> +
>> +    static_key_slow_inc(&paravirt_unfairlocks_enabled);
>> +    printk(KERN_INFO "KVM setup unfair spinlock\n");
>> +
>> +    return 0;
>> +}
>> +early_initcall(kvm_unfair_locks_init_jump);
>> +#endif
>>
>
> No!  Please do what I asked you to do.  You are not handling Hyper-V 
> or VMWare.  Just use X86_FEATURE_HYPERVISOR and it will cover all 
> hypervisors that actually follow Intel's guidelines.
>
> Paolo

OK, I can modify the patch to use X86_FEATURE_HYPERVISOR.

-Longman