From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 747D8C433E1 for ; Tue, 25 Aug 2020 19:49:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5065820782 for ; Tue, 25 Aug 2020 19:49:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="g1XjYt4T"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="2g3lJNGu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726706AbgHYTtK (ORCPT ); Tue, 25 Aug 2020 15:49:10 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:51978 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726149AbgHYTtJ (ORCPT ); Tue, 25 Aug 2020 15:49:09 -0400 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1598384947; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Nx2guUxaBEVRMrKDYjrAwhgM23aIhrP6oY6kMfLb3ZY=; b=g1XjYt4TEhfIY6zrAYI2vv7JWz6a8/qZG+rhV5sdrhKQwt5rS3GTPX98RLngamtPG9Z0Y3 ntvwf0MVpAvbdcNSDVleHqSaE4p5MlEYpYwvz7nk29+5U2TCyOKncN04dwSr0OWPdIgPJG A0QSLZ0sA0h+HgZx/mQgRmO6I4yG2sHs1lsqMr3E/5CqXK42C+h/ARaLPPjp2MWk1QlXyk v8uEnyfhYM2ViD4JqdUrsapwJA+hp33e9/oG1extMtwpcl8QfTKvS1iv25lguijo5REdDp E/ZBLpZDhpgjaK4SpEzZRinrpGEDdfHgzczMI7oVnvGJo4BWezDtXkkgGUrtOQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1598384947; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Nx2guUxaBEVRMrKDYjrAwhgM23aIhrP6oY6kMfLb3ZY=; b=2g3lJNGuoxX9O8r/+8OdIEIqhjw+1a9reAJCb6GL7K9VJOf6bRa85U3T6T4Bopph0LPMC4 HIa0NGsb+LXwOSCA== To: "Luck\, Tony" , Andy Lutomirski , "Christopherson\, Sean J" Cc: Andrew Cooper , LKML , X86 ML , Linus Torvalds , Tom Lendacky , Pu Wen , Stephen Hemminger , Sasha Levin , Dirk Hohndel , Jan Kiszka , Tony W Wang-oc , "H. Peter Anvin" , "Mallick\, Asit K" , Gordon Tetlow , David Kaplan Subject: RE: TDX #VE in SYSCALL gap (was: [RFD] x86: Curing the exception and syscall trainwreck in hardware) In-Reply-To: References: <875z98jkof.fsf@nanos.tec.linutronix.de> <3babf003-6854-e50a-34ca-c87ce4169c77@citrix.com> <20200825043959.GF15046@sjchrist-ice> <20200825171903.GA20660@sjchrist-ice> Date: Tue, 25 Aug 2020 21:49:07 +0200 Message-ID: <87ft8ay098.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 25 2020 at 17:35, Tony Luck wrote: >> > Or malicious hypervisor action, and that's a problem. >> > >> > Suppose the hypervisor remaps a GPA used in the SYSCALL gap (e.g. the >> > actual SYSCALL text or the first memory it accesses -- I don't have a >> > TDX spec so I don't know the details). > > Is it feasible to defend against a malicious (or buggy) hypervisor? > > Obviously, we can't leave holes that guests can exploit. But the hypervisor > can crash the system no matter how clever TDX is. If it crashes and burns reliably then fine, but is that guaranteed? I have serious doubts about that given the history and fragility of all of this and I really have zero interest in dealing with the fallout a year from now. Thanks, tglx