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From: Paolo Bonzini <pbonzini@redhat.com>
To: Xiao Guangrong <guangrong.xiao@linux.intel.com>,
	Lan Tianyu <tianyu.lan@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>
Cc: gleb@kernel.org, mingo@redhat.com, hpa@zytor.com, x86@kernel.org,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] KVM: Remove redundant smp_mb() in the kvm_mmu_commit_zap_page()
Date: Thu, 10 Mar 2016 16:31:10 +0100	[thread overview]
Message-ID: <56E1933E.20909@redhat.com> (raw)
In-Reply-To: <56E19224.9090906@redhat.com>



On 10/03/2016 16:26, Paolo Bonzini wrote:
> Compared to smp_load_acquire(), smp_mb() adds an ordering between stores
> and loads.

Here, the ordering is load-store, hence...

> The load of kvm->tlbs_dirty should then be
> 
> 	/*
> 	 * Read tlbs_dirty before setting KVM_REQ_TLB_FLUSH in
> 	 * kvm_make_all_cpus_request.  This
> 	 */
> 	long dirty_count = smp_load_acquire(kvm->tlbs_dirty);
> 
> Tianyu, I think Xiao provided the information that I was missing.  Would
> you like to prepare the patch?

Thanks,

Paolo

  reply	other threads:[~2016-03-10 15:31 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-04  1:35 [PATCH] KVM: Remove redundant smp_mb() in the kvm_mmu_commit_zap_page() Lan Tianyu
2016-03-04  7:21 ` Thomas Gleixner
2016-03-04  7:12   ` Lan Tianyu
2016-03-04  8:49     ` Paolo Bonzini
2016-03-08  8:36       ` Lan Tianyu
2016-03-08 15:27         ` Paolo Bonzini
2016-03-09  7:18           ` Lan Tianyu
2016-03-10 17:07             ` Paolo Bonzini
2016-03-10 18:08               ` Xiao Guangrong
2016-03-10 14:40           ` Xiao Guangrong
2016-03-10 15:26             ` Paolo Bonzini
2016-03-10 15:31               ` Paolo Bonzini [this message]
2016-03-10 15:45                 ` Xiao Guangrong
2016-03-10 16:04                   ` Paolo Bonzini
2016-03-10 17:57                     ` Xiao Guangrong
2016-03-11  1:13               ` Lan Tianyu
2016-03-04  8:04 ` Paolo Bonzini
2016-03-04 13:48   ` Xiao Guangrong

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