From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linutronix.de (146.0.238.70:993) by crypto-ml.lab.linutronix.de with IMAP4-SSL for ; 22 Feb 2019 09:20:26 -0000 Received: from merlin.infradead.org ([2001:8b0:10b:1231::1]) by Galois.linutronix.de with esmtps (TLS1.2:RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1gx70K-0001Lh-Uk for speck@linutronix.de; Fri, 22 Feb 2019 10:20:25 +0100 Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gx70J-0001Bs-M4 for speck@linutronix.de; Fri, 22 Feb 2019 09:20:23 +0000 Date: Fri, 22 Feb 2019 10:20:21 +0100 From: Peter Zijlstra Subject: [MODERATED] Re: [patch V3 5/9] MDS basics 5 Message-ID: <20190222092021.GW32494@hirez.programming.kicks-ass.net> References: <20190221234431.922117624@linutronix.de> <20190221235534.821554289@linutronix.de> <7e028ea7-dcc7-e931-a888-df60f69a348c@citrix.com> MIME-Version: 1.0 In-Reply-To: <7e028ea7-dcc7-e931-a888-df60f69a348c@citrix.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable To: speck@linutronix.de List-ID: On Fri, Feb 22, 2019 at 12:46:46AM +0000, speck for Andrew Cooper wrote: > On 21/02/2019 23:44, speck for Thomas Gleixner wrote: > > + There is one non maskable exception which returns through paranoid ex= it > > + and is not mitigated: #DF. If user space is able to trigger a double > > + fault the possible MDS leakage is the least problem to worry about. >=20 > What about espfix64?=C2=A0 An IRET fault from that ends up at #DF, and > purposefully recovers.=C2=A0 It is trigger-able from at least modify_ldt(). >=20 > The #DF path is normally fatal, but in the cases that it's not, an extra > VERW isn't going to be the slow part. What about the #MC, do_mce has paranoid=3D1 on.