On 2016/02/24 22:17, Paolo Bonzini wrote:
> Move the call to kvm_mmu_flush_or_zap outside the loop.
> 
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> ---
>   arch/x86/kvm/mmu.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index 725316df32ec..6d47b5c43246 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -2029,24 +2029,27 @@ static void mmu_sync_children(struct kvm_vcpu *vcpu,
>       struct mmu_page_path parents;
>       struct kvm_mmu_pages pages;
>       LIST_HEAD(invalid_list);
> +     bool flush = false;
>   
>       while (mmu_unsync_walk(parent, &pages)) {
>               bool protected = false;
> -             bool flush = false;
>   
>               for_each_sp(pages, sp, parents, i)
>                       protected |= rmap_write_protect(vcpu, sp->gfn);
>   
> -             if (protected)
> +             if (protected) {
>                       kvm_flush_remote_tlbs(vcpu->kvm);
> +                     flush = false;
> +             }
>   
>               for_each_sp(pages, sp, parents, i) {
>                       flush |= kvm_sync_page(vcpu, sp, &invalid_list);
>                       mmu_pages_clear_parents(&parents);
>               }
> -             kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush);
>               cond_resched_lock(&vcpu->kvm->mmu_lock);

This may release the mmu_lock before committing the zapping.
Is it safe?  If so, we may want to see the reason in the changelog.

  Takuya

>       }
> +
> +     kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush);
>   }
>   
>   static void __clear_sp_write_flooding_count(struct kvm_mmu_page *sp)
> 



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