From owner-freebsd-arch@freebsd.org Mon Jan 25 19:59:57 2021 Return-Path: Delivered-To: freebsd-arch@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 7EFD14EFD40 for ; Mon, 25 Jan 2021 19:59:57 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from smtp.freebsd.org (smtp.freebsd.org [96.47.72.83]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4DPggx2jsJz3Fx2; Mon, 25 Jan 2021 19:59:57 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from John-Baldwins-MacBook-Pro.local (unknown [IPv6:2601:648:8681:1cb0:5c12:2e91:6a1e:30bf]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) (Authenticated sender: jhb) by smtp.freebsd.org (Postfix) with ESMTPSA id 9A8421E37; Mon, 25 Jan 2021 19:59:56 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Subject: Re: Should we enable KERN_TLS on amd64 for FreeBSD 13? To: Allan Jude , Andrew Gallatin , freebsd-arch@FreeBSD.org, Ed Maste References: <8eff83e5-49bc-d410-626e-603c03877b80@cs.duke.edu> From: John Baldwin Message-ID: Date: Mon, 25 Jan 2021 11:59:55 -0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 25 Jan 2021 19:59:57 -0000 On 1/25/21 10:45 AM, Allan Jude wrote: > On 2021-01-08 12:26, Andrew Gallatin wrote: >> >> Kernel TLS (KTLS) support was added roughly a year ago, and provides >> an efficient software or hardware accelerated path to have the kernel >> (or the NIC) handle TLS crypto.  This is quite useful for web and >> NFS servers, and provides a huge (2x -> 5x) efficiency gain by >> avoiding data copies into userspace for crypto, and potentially >> offloading the crypto to hardware. >> >> >> KTLS is well tested on amd64, having been used in production at Netflix >> for nearly 4 years.   The vast majority of Netflix video has been served >> via KTLS for the last few years.  Its what has allowed us to serve >> 100Gb/s on Xeon 2697A cpus for years, and what allows us to serve >> nearly 400Gb/s on AMD servers with NICs which support crypto offload. >> >> I have received a few requests to enable it by default in GENERIC, and >> I'd like to get some opinions. >> >> There are essentially 3 options >> >> 1) Fully enable KTLS by adding 'options KERN_TLS' to GENERIC, and >> flipping kern.ipc.tls.enable=1 >> >> The advantage of this is that it "just works" out of the box for users, >> and for reviewers. >> >> The drawback is that new code is thrust on unsuspecting users, >> potentially exposing them to bugs that we have not found in our >> somewhat limited web serving workload. >> >> 2) Enable KTLS in GENERIC, but leave it turned off by default. >> >> This option allows users to enable ktls without a rebuild of GENERIC, >> but does not enable it by default. So they can enable it if they >> know about it, but are protected from bugs. >> >> The disadvantages of this are that it increases the kernel size >> by ~20K, starts up one thread per core on every amd64 machine, >> and it adds more required tuning to get good performance from FreeBSD. >> >> >> 3) Continue along with KTLS disabled in GENERIC >> >> This is the lowest risk, but adds a higher bar for users wanting >> to use ktls. >> >> >> >> Note that the discussion is focused on amd64 only, as KTLS will >> only work on 64-bit platforms which use a direct map.  It has >> not been tested at all on ppc64, and currently causes a >> panic-at-boot on arm64 due to what are suspected to be problems >> in the arm64 PCB setup. See: >> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=247945 >> >> Drew >> > > Just before this went in, Ed cleaned up the arm64 GENERIC to get it > closer to the amd64 one. Can we enable KERN_TLS in arm64 GENERIC as well? Well, I also fixed a bug KERN_TLS exposed on arm64 that was gating for this (247945). I would not be opposed to enabling it on arm64, but I have not personally tested it on arm64. If someone can verify it works ok on arm64 I'd be happy for it to be enabled there. -- John Baldwin