Re: [dpdk-dev] [PATCH v2] examples/vhost_crypto: fix zero copy

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 11/16/2018 10:48 AM, Maxime Coquelin wrote:
> 
> 
> On 11/14/18 12:16 PM, Fan Zhang wrote:
>> This patch fixes the zero copy enable problem for vhost crypto
>> sample application.
>>
>> For some Crypto PMDs such as AESNI-MB and AESNI-GCM the data to
>> be processed will be made a copy in the same buffer but next to the
>> data. For example, to encrypt 64 bytes data the PMD will copy this
>> data from offset 64 to offset 123. This requires the application
>> provides the buffer with at least double of the data size.
>>
>> However there is no way for VMs to know this limitation. When
>> zero-copy is enabled in Vhost the PMD may overwrite the buffer
>> next to the VM data to be processed, and further cause problems
>> such as Segmentation Fault or even worse, crashes the VM.
>>
>> To fix the problem the user should avoid enabling the zero copy
>> for these Crypto PMDs. This patch adds the checking of the PMD
>> names to see if zero copy can be applied.
>>
>> Fixes: 709521f4c2cd ("examples/vhost_crypto: support multi-core")
>>
>> Signed-off-by: Fan Zhang <roy.fan.zhang@intel.com>
>> ---
>> v2:
>> - removed unecessary checks
>> - Changed log message when zero-copy is not applicable.
>>
>>   examples/vhost_crypto/main.c | 17 +++++++++++++++++
>>   1 file changed, 17 insertions(+)
>>
> 
> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Applied to dpdk-next-net/master, thanks.