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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 DA2CDC433DB for ; Sat, 13 Feb 2021 09:38:47 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 819D861490 for ; Sat, 13 Feb 2021 09:38:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 819D861490 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id F07D38D00C0; Sat, 13 Feb 2021 04:38:46 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EB9C28D0060; Sat, 13 Feb 2021 04:38:46 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DA70D8D00C0; Sat, 13 Feb 2021 04:38:46 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0234.hostedemail.com [216.40.44.234]) by kanga.kvack.org (Postfix) with ESMTP id C24058D0060 for ; Sat, 13 Feb 2021 04:38:46 -0500 (EST) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 77801180255B7 for ; Sat, 13 Feb 2021 09:38:46 +0000 (UTC) X-FDA: 77812745052.02.8BA9401 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf02.hostedemail.com (Postfix) with ESMTP id A4C82407F8DF for ; Sat, 13 Feb 2021 09:38:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=mWJvVJACvFScrB2vebO1a+QtpFPtimGD/qsrp7JzPqY=; b=HisRhfraJdwK4126cj8ntjaBTw Hs3A1IjOv95JebZkjEjEUl+ASLg/tZNvc0tpnB7+UfW62yAxn7wCoH3j3U2Hn4GvccCU3X6Un+K/Z s623ixK2yJdO2IN4X61WU/fAXc64UK2s0bORgx84K8EoOGung9OrRWOsMhRKtbeEebg3bb1zp3NWd fk0o+J31QrZ8eCJiQ7ag4o+UBFQIGb2DK3aDY1RV6jaETjgZsIy7q8DclRXUB/8pQO9pQ6g+w2dDq IEwb4/rJQLUk6p8vA5k/lnO7Xgi7LTril49BWG2cwcrBFbqkHVw/pMlxCZEBKSPvEuxGuODWJleL/ iErvlo8A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lArNm-00CkBF-TD; Sat, 13 Feb 2021 09:38:31 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id B347B3003E1; Sat, 13 Feb 2021 10:38:28 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id A27D820299B4B; Sat, 13 Feb 2021 10:38:28 +0100 (CET) Date: Sat, 13 Feb 2021 10:38:28 +0100 From: Peter Zijlstra To: Andi Kleen Cc: Joerg Roedel , David Rientjes , Borislav Petkov , Andy Lutomirski , Sean Christopherson , Andrew Morton , "Kirill A. Shutemov" , Brijesh Singh , Tom Lendacky , Jon Grimm , Thomas Gleixner , Christoph Hellwig , Paolo Bonzini , Ingo Molnar , x86@kernel.org, linux-mm@kvack.org Subject: Re: AMD SEV-SNP/Intel TDX: validation of memory pages Message-ID: References: <7515a81a-19e-b063-2081-3f5e79f0f7a8@google.com> <20210212131907.GI5453@suse.de> <20210212145318.GK5453@suse.de> <20210212152813.GA28884@suse.de> <20210212214205.GF365765@tassilo.jf.intel.com> <20210212215852.GL8912@worktop.programming.kicks-ass.net> <20210212223918.GG365765@tassilo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210212223918.GG365765@tassilo.jf.intel.com> X-Stat-Signature: 9c8sanqrpn5syu9jq6nxt3iae3d9an3s X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: A4C82407F8DF Received-SPF: none (infradead.org>: No applicable sender policy available) receiver=imf02; identity=mailfrom; envelope-from=""; helo=casper.infradead.org; client-ip=90.155.50.34 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1613209121-516760 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Feb 12, 2021 at 02:39:18PM -0800, Andi Kleen wrote: > > But AFAI recursive #VE is entirely possible. The moment #VE reads that > > ve_info thing, NMIs can happen, which can trigger another #VE which then > > clobbers your stack and we're irrecoverably screwed again. > > I don't believe we have anything currently in the NMI handler that > would trigger #VE. While some operations may need TDCALL (like MSR > accesses) those should be all directly hooked. > > Also in general to avoid clobbering your stack you would just need > to make sure to adjust the IST stack before you do anything that > could cause another #VE. NMI can touch user-pages, which then brings the on-demand #VE.