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From: Jason Wang <jasowang@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	jgg@mellanox.com, aarcange@redhat.com, jglisse@redhat.com,
	linux-mm@kvack.org,
	James Bottomley <James.Bottomley@hansenpartnership.com>,
	Christoph Hellwig <hch@infradead.org>,
	David Miller <davem@davemloft.net>,
	linux-arm-kernel@lists.infradead.org,
	linux-parisc@vger.kernel.org
Subject: Re: [PATCH 2/2] vhost: re-introducing metadata acceleration through kernel virtual address
Date: Mon, 9 Sep 2019 15:23:58 +0800
Message-ID: <4ee20058-0beb-111c-6750-556965423f04@redhat.com> (raw)
In-Reply-To: <20190909004504-mutt-send-email-mst@kernel.org>


On 2019/9/9 下午12:45, Michael S. Tsirkin wrote:
>>> Since idx can be speculated, I guess we need array_index_nospec here?
>> So we have
>>
>> ACQUIRE(mmu_lock)
>>
>> get idx
>>
>> RELEASE(mmu_lock)
>>
>> ACQUIRE(mmu_lock)
>>
>> read array[idx]
>>
>> RELEASE(mmu_lock)
>>
>> Then I think idx can't be speculated consider we've passed RELEASE +
>> ACQUIRE?
> I don't think memory barriers have anything to do with speculation,
> they are architectural.
>

Oh right. Let me add array_index_nospec() in next version.

Thanks


  reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190905122736.19768-1-jasowang@redhat.com>
2019-09-05 12:27 ` Jason Wang
2019-09-08 11:05   ` Michael S. Tsirkin
2019-09-09  2:18     ` Jason Wang
2019-09-09  2:30       ` Jason Wang
2019-09-09  4:45       ` Michael S. Tsirkin
2019-09-09  7:23         ` Jason Wang [this message]
     [not found] ` <20190906032154.9376-1-hdanton@sina.com>
2019-09-06 12:51   ` Jason Wang

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