Re: [PATCH v8 1/1] crypto: add virtio-crypto driver

From	Christian Borntraeger <borntraeger@de.ibm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v8 1/1] crypto: add virtio-crypto driver
Date	2017-01-12 15:20 +0100
Message-ID	<sYOop-4Za-15@gated-at.bofh.it> (permalink)
References	<sOtEB-8g3-1@gated-at.bofh.it> <sOtOi-8jg-13@gated-at.bofh.it> <sY3IS-1gX-7@gated-at.bofh.it> <sY3Sx-1k3-1@gated-at.bofh.it> <sY4bT-1qK-5@gated-at.bofh.it>
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On 01/10/2017 01:56 PM, Christian Borntraeger wrote:
> On 01/10/2017 01:36 PM, Gonglei (Arei) wrote:
>> Hi,
>>
>>>
>>> On 12/15/2016 03:03 AM, Gonglei wrote:
>>> [...]
>>>> +
>>>> +static struct crypto_alg virtio_crypto_algs[] = { {
>>>> +	.cra_name = "cbc(aes)",
>>>> +	.cra_driver_name = "virtio_crypto_aes_cbc",
>>>> +	.cra_priority = 501,
>>>
>>>
>>> This is still higher than the hardware-accelerators (like intel aesni or the
>>> s390 cpacf functions or the arm hw). aesni and s390/cpacf are supported by the
>>> hardware virtualization and available to the guests. I do not see a way how
>>> virtio
>>> crypto can be faster than that (in the end it might be cpacf/aesni + overhead)
>>> instead it will very likely be slower.
>>> So we should use a number that is higher than software implementations but
>>> lower than the hw ones.
>>>
>>> Just grepping around, the software ones seem be be around 100 and the
>>> hardware
>>> ones around 200-400. So why was 150 not enough?
>>>
>> I didn't find a documentation about how we use the priority, and I assumed
>> people use virtio-crypto will configure hardware accelerators in the
>> host. So I choosed the number which bigger than aesni's priority.
> 
> Yes, but the aesni driver will only bind if there is HW support in the guest.
> And if aesni is available in the guest (or the s390 aes function from cpacf)
> it will always be faster than the same in the host via virtio.So your priority
> should be smaller.


any opinion on this?

Thread

Re: [PATCH v8 1/1] crypto: add virtio-crypto driver Christian Borntraeger <borntraeger@de.ibm.com> - 2017-01-10 13:30 +0100
  RE: [PATCH v8 1/1] crypto: add virtio-crypto driver "Gonglei (Arei)" <arei.gonglei@huawei.com> - 2017-01-10 13:40 +0100
    Re: [PATCH v8 1/1] crypto: add virtio-crypto driver Christian Borntraeger <borntraeger@de.ibm.com> - 2017-01-10 14:00 +0100
      Re: [PATCH v8 1/1] crypto: add virtio-crypto driver Christian Borntraeger <borntraeger@de.ibm.com> - 2017-01-12 15:20 +0100
        Re: [PATCH v8 1/1] crypto: add virtio-crypto driver "Michael S. Tsirkin" <mst@redhat.com> - 2017-01-12 15:30 +0100
          RE: [PATCH v8 1/1] crypto: add virtio-crypto driver "Gonglei (Arei)" <arei.gonglei@huawei.com> - 2017-01-13 03:00 +0100

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