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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	[thread overview]
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


WARNING: multiple messages have this Message-ID (diff)
From: Jason Wang <jasowang@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: aarcange@redhat.com, Christoph Hellwig <hch@infradead.org>,
	linux-parisc@vger.kernel.org, kvm@vger.kernel.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	James Bottomley <James.Bottomley@hansenpartnership.com>,
	linux-mm@kvack.org, jglisse@redhat.com, jgg@mellanox.com,
	David Miller <davem@davemloft.net>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 2/2] vhost: re-introducing metadata acceleration through kernel virtual address
Date: Mon, 9 Sep 2019 15:23:58 +0800	[thread overview]
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


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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2019-09-09  7:24 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-05 12:27 [PATCH 0/2] Revert and rework on the metadata accelreation Jason Wang
2019-09-05 12:27 ` [PATCH 1/2] Revert "vhost: access vq metadata through kernel virtual address" Jason Wang
2019-09-05 12:27 ` Jason Wang
2019-09-06 13:46   ` Michael S. Tsirkin
2019-09-09  7:16     ` Jason Wang
2019-09-09  7:16     ` Jason Wang
2019-09-06 13:46   ` Michael S. Tsirkin
2019-09-05 12:27 ` [PATCH 2/2] vhost: re-introducing metadata acceleration through kernel virtual address Jason Wang
2019-09-05 12:27   ` Jason Wang
2019-09-08 11:05   ` Michael S. Tsirkin
2019-09-08 11:05     ` Michael S. Tsirkin
2019-09-09  2:18     ` Jason Wang
2019-09-09  2:18     ` Jason Wang
2019-09-09  2:18       ` Jason Wang
2019-09-09  2:30       ` Jason Wang
2019-09-09  2:30         ` Jason Wang
2019-09-09  2:30       ` Jason Wang
2019-09-09  4:45       ` Michael S. Tsirkin
2019-09-09  4:45         ` Michael S. Tsirkin
2019-09-09  4:45         ` Michael S. Tsirkin
2019-09-09  7:23         ` Jason Wang
2019-09-09  7:23         ` Jason Wang [this message]
2019-09-09  7:23           ` Jason Wang
2019-09-08 11:05   ` Michael S. Tsirkin
2019-09-05 12:27 ` Jason Wang
2019-09-05 13:59 ` [PATCH 0/2] Revert and rework on the metadata accelreation Jason Gunthorpe
2019-09-05 13:59 ` Jason Gunthorpe
2019-09-05 13:59   ` Jason Gunthorpe
2019-09-06 10:02   ` Jason Wang
2019-09-06 10:02   ` Jason Wang
2019-09-06 10:02     ` Jason Wang
2019-09-06 13:15     ` David Miller
2019-09-09  7:18       ` Jason Wang
2019-09-09  7:18       ` Jason Wang
2019-09-09 12:15         ` Michael S. Tsirkin
2019-09-09 12:15         ` Michael S. Tsirkin
2019-09-06 13:15     ` David Miller
2019-09-07 15:03     ` Jason Gunthorpe
2019-09-07 15:03       ` Jason Gunthorpe
2019-09-07 15:03       ` Jason Gunthorpe
2019-09-09  2:29       ` Jason Wang
2019-09-09  2:29         ` Jason Wang
2019-09-09  2:29       ` Jason Wang
2019-09-06  3:21 ` [PATCH 2/2] vhost: re-introducing metadata acceleration through kernel virtual address Hillf Danton
2019-09-06  3:21   ` Hillf Danton
2019-09-06 12:51   ` Jason Wang
2019-09-06 12:51     ` Jason Wang
2019-09-06 12:51   ` Jason Wang
2019-09-06  3:21 ` Hillf Danton

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