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

[Gonglei (Arei)]

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.

Regards,
-Gonglei