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=-1.1 required=3.0 tests=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 BEDDFC433DF for ; Tue, 23 Jun 2020 16:10:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 93E6A20702 for ; Tue, 23 Jun 2020 16:10:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="HF6CnrEx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732224AbgFWQKW (ORCPT ); Tue, 23 Jun 2020 12:10:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41950 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728472AbgFWQKW (ORCPT ); Tue, 23 Jun 2020 12:10:22 -0400 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 235E4C061573; Tue, 23 Jun 2020 09:10:22 -0700 (PDT) Received: from zn.tnic (p200300ec2f0d47007938aef930b6c4fb.dip0.t-ipconnect.de [IPv6:2003:ec:2f0d:4700:7938:aef9:30b6:c4fb]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 445861EC0390; Tue, 23 Jun 2020 18:10:18 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1592928618; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=gRvNeLgnj5EUYtezLWiSTfwu1q6G/wPTT9fdfyj9xYQ=; b=HF6CnrExk3oqYwLL7mzTIOKSsMDwnWe7KIL7Waj5xzeGYvsheaQPN2zwe3L4v9bRqaYG4p EbVI8ncLyIZjl4G5EBxgSjDAQS4/izgGnmNmB6re445rstGW+hSsroF+PmiaIEAQ7DwxNc u/r/VHsDr5fc86TkEBe6YgmjNWYfxXI= Date: Tue, 23 Jun 2020 18:10:10 +0200 From: Borislav Petkov To: Andrew Cooper Cc: Peter Zijlstra , Joerg Roedel , Andy Lutomirski , Joerg Roedel , Dave Hansen , Tom Lendacky , Mike Stunes , Dan Williams , Dave Hansen , "H. Peter Anvin" , Juergen Gross , Jiri Slaby , Kees Cook , kvm list , LKML , Thomas Hellstrom , Linux Virtualization , X86 ML , Sean Christopherson Subject: Re: Should SEV-ES #VC use IST? (Re: [PATCH] Allow RDTSC and RDTSCP from userspace) Message-ID: <20200623161010.GE32590@zn.tnic> References: <20200623104559.GA4817@hirez.programming.kicks-ass.net> <20200623111107.GG31822@suse.de> <20200623111443.GC4817@hirez.programming.kicks-ass.net> <20200623114324.GA14101@suse.de> <20200623115014.GE4817@hirez.programming.kicks-ass.net> <20200623121237.GC14101@suse.de> <20200623130322.GH4817@hirez.programming.kicks-ass.net> <20200623144940.GE14101@suse.de> <20200623151607.GJ4817@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 23, 2020 at 04:32:22PM +0100, Andrew Cooper wrote: > MSR_MCG_STATUS.MCIP, and yes - any #MC before that point will > immediately Shutdown.  Any #MC between that point and IRET will clobber > its IST stack and end up sad. Well, at some point we should simply accept that we're living a little on the edge. That is, until we get IRET with a mask of to-reenable vectors which has #MC, NMI and whatever else vectors. It would be even better if that mask were configurable. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette