From: Olivier Matz <olivier.matz@6wind.com>
To: "Tan, Jianfeng" <jianfeng.tan@intel.com>,
"dev@dpdk.org" <dev@dpdk.org>,
"Xie, Huawei" <huawei.xie@intel.com>,
"yuanhan.liu@linux.intel.com" <yuanhan.liu@linux.intel.com>
Subject: Re: [dpdk-dev] [PATCH] virtio: fix packet corruption
Date: Tue, 19 Jul 2016 15:59:51 +0200 [thread overview]
Message-ID: <1c15f3d4-ed12-c315-cf88-8a71cc6fee5f@6wind.com> (raw)
In-Reply-To: <ED26CBA2FAD1BF48A8719AEF02201E36106216C8@SHSMSX103.ccr.corp.intel.com>
Hi,
On 07/19/2016 03:57 PM, Tan, Jianfeng wrote:
>
>
>> -----Original Message-----
>> From: Olivier Matz [mailto:olivier.matz@6wind.com]
>> Sent: Tuesday, July 19, 2016 9:11 PM
>> To: Tan, Jianfeng; dev@dpdk.org; Xie, Huawei; yuanhan.liu@linux.intel.com
>> Subject: Re: [PATCH] virtio: fix packet corruption
>>
>> Hi Jianfeng,
>>
>> On 07/19/2016 03:03 PM, Tan, Jianfeng wrote:
>>> Hi Oliver,
>>>
>>>> -----Original Message-----
>>>> From: Olivier Matz [mailto:olivier.matz@6wind.com]
>>>> Sent: Tuesday, July 19, 2016 8:32 PM
>>>> To: dev@dpdk.org; Tan, Jianfeng; Xie, Huawei;
>> yuanhan.liu@linux.intel.com
>>>> Subject: [PATCH] virtio: fix packet corruption
>>>>
>>>> The support of virtio-user changed the way the mbuf dma address is
>>>> retrieved, using a physical address in case of virtio-pci and a virtual
>>>> address in case of virtio-user.
>>>>
>>>> This change introduced some possible memory corruption in packets,
>>>> replacing:
>>>> m->buf_physaddr + RTE_PKTMBUF_HEADROOM
>>>> by:
>>>> m->buf_physaddr + m->data_off (through a macro)
>>>>
>>>> This patch fixes this issue, restoring the original behavior.
>>>
>>> Could you be more specific on why we cannot use m->data_off here?
>>
>> There is no guarantee that m->data_off == RTE_PKTMBUF_HEADROOM here
>> as
>> virtqueue_enqueue_recv_refill() is called on a mbuf that is just
>> allocated with rte_mbuf_raw_alloc(). An alternative would be to set
>> data_off to RTE_PKTMBUF_HEADROOM, but as it's a fix and we are close to
>> the release, I prefered to restore the initial behavior.
>
> Oh yes, gotcha.
>
> But if we do not set data_off properly, it's still buggy when others consume these mbufs, right?
>
This is done later in virtio_recv_pkts*() functions, one the host has
written the data in the mbuf.
next prev parent reply other threads:[~2016-07-19 14:00 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-19 12:31 Olivier Matz
2016-07-19 13:03 ` Tan, Jianfeng
2016-07-19 13:11 ` Olivier Matz
2016-07-19 13:57 ` Tan, Jianfeng
2016-07-19 13:59 ` Olivier Matz [this message]
2016-07-19 14:23 ` Tan, Jianfeng
2016-07-21 8:28 ` Yuanhan Liu
2016-07-21 22:28 ` Thomas Monjalon
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