linux-kernel - Re: [PATCH V2 03/10] KVM: Remove tlbs

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Date:   Thu, 23 Sep 2021 17:23:05 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Lai Jiangshan <jiangshanlai@...il.com>,
        linux-kernel@...r.kernel.org
Cc:     Lai Jiangshan <laijs@...ux.alibaba.com>, kvm@...r.kernel.org
Subject: Re: [PATCH V2 03/10] KVM: Remove tlbs_dirty

On 18/09/21 02:56, Lai Jiangshan wrote:
> From: Lai Jiangshan <laijs@...ux.alibaba.com>
> 
> There is no user of tlbs_dirty.
> 
> Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
> ---
>   include/linux/kvm_host.h | 1 -
>   virt/kvm/kvm_main.c      | 9 +--------
>   2 files changed, 1 insertion(+), 9 deletions(-)
> 
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index e4d712e9f760..3b7846cd0637 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -608,7 +608,6 @@ struct kvm {
>   	unsigned long mmu_notifier_range_start;
>   	unsigned long mmu_notifier_range_end;
>   #endif
> -	long tlbs_dirty;
>   	struct list_head devices;
>   	u64 manual_dirty_log_protect;
>   	struct dentry *debugfs_dentry;
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 3e67c93ca403..6d6be42ec78d 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -312,12 +312,6 @@ EXPORT_SYMBOL_GPL(kvm_make_all_cpus_request);
>   #ifndef CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL
>   void kvm_flush_remote_tlbs(struct kvm *kvm)
>   {
> -	/*
> -	 * Read tlbs_dirty before setting KVM_REQ_TLB_FLUSH in
> -	 * kvm_make_all_cpus_request.
> -	 */
> -	long dirty_count = smp_load_acquire(&kvm->tlbs_dirty);
> -
>   	/*
>   	 * We want to publish modifications to the page tables before reading
>   	 * mode. Pairs with a memory barrier in arch-specific code.
> @@ -332,7 +326,6 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
>   	if (!kvm_arch_flush_remote_tlb(kvm)
>   	    || kvm_make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH))
>   		++kvm->stat.generic.remote_tlb_flush;
> -	cmpxchg(&kvm->tlbs_dirty, dirty_count, 0);
>   }
>   EXPORT_SYMBOL_GPL(kvm_flush_remote_tlbs);
>   #endif
> @@ -537,7 +530,7 @@ static __always_inline int __kvm_handle_hva_range(struct kvm *kvm,
>   		}
>   	}
>   
> -	if (range->flush_on_ret && (ret || kvm->tlbs_dirty))
> +	if (range->flush_on_ret && ret)
>   		kvm_flush_remote_tlbs(kvm);
>   
>   	if (locked)
> 

Queued up to here for 5.15, thanks!

Paolo