From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linutronix.de (193.142.43.55:993) by crypto-ml.lab.linutronix.de with IMAP4-SSL for ; 23 Oct 2019 07:25:04 -0000 Received: from mx2.suse.de ([195.135.220.15] helo=mx1.suse.de) by Galois.linutronix.de with esmtps (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1iNB0x-0004Ka-7c for speck@linutronix.de; Wed, 23 Oct 2019 09:25:04 +0200 Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 0C563B004 for ; Wed, 23 Oct 2019 07:24:57 +0000 (UTC) Date: Wed, 23 Oct 2019 09:24:48 +0200 From: Borislav Petkov Subject: [MODERATED] Re: [PATCH v7 10/10] TAAv7 10 Message-ID: <20191023072448.GC12272@zn.tnic> References: <20191022183920.6ecpldfejup3hekf@treble> MIME-Version: 1.0 In-Reply-To: <20191022183920.6ecpldfejup3hekf@treble> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable To: speck@linutronix.de List-ID: On Tue, Oct 22, 2019 at 01:39:20PM -0500, speck for Josh Poimboeuf wrote: > Regardless, this patch adds complexity and still seems very fragile. It > will add maintenance issues and probably introduce bugs. And, most > importantly there's *still* not a real world justification for it. > Please drop it from the series. Yeah, and here's nasty use case if we did the runtime toggle thing: you boot with TSX on, start guests, they see TSX and start using it and then you disable it in the host. I believe I read somewhere Andrew saying it won't #UD but it would abort all transactions, which is still not nice and leaves the burden on the sysadmin explaining why guests experience perf penatly all of a sudden. Not good. --=20 Regards/Gruss, Boris. SUSE Software Solutions Germany GmbH, GF: Felix Imend=C3=B6rffer, HRB 36809, = AG N=C3=BCrnberg --=20