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,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 D261CC433E1 for ; Thu, 20 Aug 2020 17:21:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ABA3420724 for ; Thu, 20 Aug 2020 17:21:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="DkpdICMe" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730568AbgHTRVn (ORCPT ); Thu, 20 Aug 2020 13:21:43 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:31154 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730544AbgHTRVc (ORCPT ); Thu, 20 Aug 2020 13:21:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1597944089; 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=rvDNF5Q3wwtznjdzEy9L2Cc3y4PlB8JtkjTiFM9v96o=; b=DkpdICMe113oxxJXIOehcL4LNQRw8VTuKvnZzLwRbEukHCy1ZemG0oJUdSfpWm39cDi9qW 1yd1AXYB31TtFZm9/jW5Kz0mEFevum7+0zoYaPPWbwI58cgH+T6DpCmf6F7T351LJM3aPy MgU63+Cwaj2yBVY/HYSpx/Cp081sUnM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-172-DJeVJEdTNtK3jEvIg62OwQ-1; Thu, 20 Aug 2020 13:21:25 -0400 X-MC-Unique: DJeVJEdTNtK3jEvIg62OwQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 824E8873155; Thu, 20 Aug 2020 17:21:23 +0000 (UTC) Received: from treble (ovpn-117-70.rdu2.redhat.com [10.10.117.70]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A46305C893; Thu, 20 Aug 2020 17:21:20 +0000 (UTC) Date: Thu, 20 Aug 2020 12:21:18 -0500 From: Josh Poimboeuf To: Andy Lutomirski Cc: peterz@infradead.org, Brian Gerst , the arch/x86 maintainers , Linux Kernel Mailing List , Kyle Huey , Alexandre Chartre , Robert O'Callahan , "Paul E. McKenney" , Frederic Weisbecker , Paolo Bonzini , Sean Christopherson , Masami Hiramatsu , Petr Mladek , Steven Rostedt , Joel Fernandes , Boris Ostrovsky , Juergen Gross , Andy Lutomirski Subject: Re: [RFC][PATCH 4/7] x86/debug: Move historical SYSENTER junk into exc_debug_kernel() Message-ID: <20200820172118.n5injemo3ic63x6j@treble> References: <20200820163453.GE1362448@hirez.programming.kicks-ass.net> <156769F5-0BCC-4FB8-A56D-0E92601F558A@amacapital.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <156769F5-0BCC-4FB8-A56D-0E92601F558A@amacapital.net> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 20, 2020 at 09:43:15AM -0700, Andy Lutomirski wrote: > > > > On Aug 20, 2020, at 9:35 AM, peterz@infradead.org wrote: > > > > On Thu, Aug 20, 2020 at 11:17:29AM -0500, Josh Poimboeuf wrote: > >> On Thu, Aug 20, 2020 at 05:21:11PM +0200, peterz@infradead.org wrote: > > > >>> qemu-gdb stub should eat the event before it lands in the guest > >> > >> Are we sure about that? I triggered the warning just now, stepping > >> through the debug handler. > > > > Not sure at all, that's what seemed reasonable, but since when did that > > stop virt ;-) > > > > Also, can you trigger that same with upstream? Because I suspect this > > ought to tickle the old code too. > > I’ve lost track of how many bugs QEMU and KVM have in this space. > Let’s keep it as a warning, but a bug. But let’s get rid of the > totally bogus TIF_SINGLESTEP manipulation. By "but a bug", I assume you mean "not a bug" :-) -- Josh