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Date:      Tue, 27 Oct 2020 09:24:45 -0700
From:      Benjamin Kaduk <kaduk@mit.edu>
To:        Mark Johnston <markj@freebsd.org>
Cc:        Neel Chauhan <neel@neelc.org>, freebsd-hackers@freebsd.org
Subject:   Re: QAT driver
Message-ID:  <20201027162445.GN39170@kduck.mit.edu>
In-Reply-To: <20201027130754.GE31663@raichu>
References:  <20201026200059.GA66299@raichu> <723fbd7326df42ce30cd5e361db9c736@neelc.org> <20201027032720.GB31663@raichu> <20201027045735.GJ39170@kduck.mit.edu> <20201027130754.GE31663@raichu>

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On Tue, Oct 27, 2020 at 09:07:54AM -0400, Mark Johnston wrote:
> On Mon, Oct 26, 2020 at 09:57:35PM -0700, Benjamin Kaduk wrote:
> > On Mon, Oct 26, 2020 at 11:27:20PM -0400, Mark Johnston wrote:
> > > On Mon, Oct 26, 2020 at 08:00:08PM -0700, Neel Chauhan wrote:
> > > > Hi,
> > > > 
> > > > This is great news for me with my home HPE ML110 G10/Xeon 4108 server.
> > > > 
> > > > However, I will not be able to test this patch unless it can get 
> > > > backported to 12.1 or 12.2 once it's out, and I don't expect backporting 
> > > > to happen.
> > > 
> > > Indeed, it wouldn't appear before 12.3.
> > > 
> > > > I have one question about this: will I be able to use this to accelerate 
> > > > OpenSSL? Is additional code needed?
> > > 
> > > In principle OpenSSL can make use of cryptodev(4) using the cryptodev
> > > engine, which would allow requests to be handled by qat(4) (or any other
> > > hardware crypto driver loaded in the kernel).  I don't know that the
> > > cryptodev engine is really maintained these days though.  More
> > 
> > The openssl cryptodev engine was rewritten in
> > https://github.com/openssl/openssl/pull/3744 , but engines are going to be
> > deprecated in openssl 3.0.
> 
> Is this the devcrypto engine?  It appears to be broken on FreeBSD: it

Yes, the devcrypto engine.

> tries to invoke CIOCGSESSION on a /dev/crypto descriptor, but one is
> supposed to first use CRIOGET to get a separate descriptor with which
> sessions are associated.

As the linked page says, "implemented based on cryptodev-linux and then
adjusted to work on FreeBSD 8.4".  I don't know of anyone testing it on a
recent FreeBSD prior to your report.

> truss(1)ing "openssl speed -evp aes-128-cbc -engine devcrypto" yields:
> 
> 82677: openat(AT_FDCWD,"/dev/crypto",O_RDWR,00)  = 3 (0x3)
> 82677: ioctl(3,CIOCGSESSION,0x7fffffffde70)      ERR#22 'Invalid argument'
> 82677: ioctl(3,CIOCGSESSION,0x7fffffffde70)      ERR#22 'Invalid argument'
> 82677: ioctl(3,CIOCGSESSION,0x7fffffffde70)      ERR#22 'Invalid argument'
> 82677: ioctl(3,CIOCGSESSION,0x7fffffffde70)      ERR#22 'Invalid argument'
> 82677: ioctl(3,CIOCGSESSION,0x7fffffffde70)      ERR#22 'Invalid argument'
> ...
> 
> > In theory someone (Intel?) could write an
> > openssl "provider" that utilizes the QAT hardware, but (unsurprisingly,
> > given that the interface isn't even finalized yet!) no one has done that
> > yet.
> 
> What's the difference between providers and engines?  There is a QAT
> engine for OpenSSL.

OpenSSL is getting a big rearchitecture for the 3.0.0 release, and
providers are the new way to provide external implementations for crypto
algorithms and such; the openssl/provider interface is arguably cleaner and
definitely more extensible than the openssl/engine interface.  There's a
bit more information at, e.g.,
https://wiki.openssl.org/index.php/OpenSSL_3.0#Providers and
https://www.openssl.org/blog/blog/2019/11/07/3.0-update/ (which links to
https://www.openssl.org/docs/OpenSSL300Design.html).

-Ben



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