Re: [PATCH] kvm uses smp_call_function_mask() inkvm_flush_remote_tlbs()

[Dor Laor <dor.laor-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Laurent Vivier wrote:
>
> This patches can be applied only on kvm-updates-2.6.24 and 
> kvm-updates-2.6.25
> as it needs smp_call_function_mask().
>
> In kvm_flush_remote_tlbs(), it replaces a loop using 
> smp_call_function_single()
> by a single call to smp_call_function_mask().
>
Would you be kind enough to copy the implementation of 
smp_call_function_mask
into external_module_compat.h so older kernel's will still work after 
this commited.
Thanks, Dor.
>
> Signed-off-by: Laurent Vivier <Laurent.Vivier-6ktuUTfB/bM@public.gmane.org>
> ---
>  drivers/kvm/kvm_main.c |   26 +++-----------------------
>  1 files changed, 3 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
> index bf6a86c..6f7b31e 100644
> --- a/drivers/kvm/kvm_main.c
> +++ b/drivers/kvm/kvm_main.c
> @@ -200,21 +200,15 @@ void vcpu_put(struct kvm_vcpu *vcpu)
>
>  static void ack_flush(void *_completed)
>  {
> -       atomic_t *completed = _completed;
> -
> -       atomic_inc(completed);
>  }
>
>  void kvm_flush_remote_tlbs(struct kvm *kvm)
>  {
> -       int i, cpu, needed;
> +       int i, cpu;
>         cpumask_t cpus;
>         struct kvm_vcpu *vcpu;
> -       atomic_t completed;
>
> -       atomic_set(&completed, 0);
>         cpus_clear(cpus);
> -       needed = 0;
>         for (i = 0; i < KVM_MAX_VCPUS; ++i) {
>                 vcpu = kvm->vcpus[i];
>                 if (!vcpu)
> @@ -223,23 +217,9 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
>                         continue;
>                 cpu = vcpu->cpu;
>                 if (cpu != -1 && cpu != raw_smp_processor_id())
> -                       if (!cpu_isset(cpu, cpus)) {
> -                               cpu_set(cpu, cpus);
> -                               ++needed;
> -                       }
> -       }
> -
> -       /*
> -        * We really want smp_call_function_mask() here.  But that's not
> -        * available, so ipi all cpus in parallel and wait for them
> -        * to complete.
> -        */
> -       for (cpu = first_cpu(cpus); cpu != NR_CPUS; cpu = 
> next_cpu(cpu, cpus))
> -               smp_call_function_single(cpu, ack_flush, &completed, 
> 1, 0);
> -       while (atomic_read(&completed) != needed) {
> -               cpu_relax();
> -               barrier();
> +                       cpu_set(cpu, cpus);
>         }
> +       smp_call_function_mask(cpus, ack_flush, NULL, 1);
>  }
>
>  int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
> --
> 1.5.2.4
>
>
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