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 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7920EC5AD49 for ; Mon, 26 May 2025 18:42:17 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.997725.1378539 (Exim 4.92) (envelope-from ) id 1uJclp-0008Ed-1F; Mon, 26 May 2025 18:41:57 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 997725.1378539; Mon, 26 May 2025 18:41:57 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1uJclo-0008EW-Ux; Mon, 26 May 2025 18:41:56 +0000 Received: by outflank-mailman (input) for mailman id 997725; Mon, 26 May 2025 18:41:56 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1uJclo-0008EO-BI for xen-devel@lists.xenproject.org; Mon, 26 May 2025 18:41:56 +0000 Received: from chassiron.antioche.eu.org (chassiron.antioche.eu.org [2001:41d0:fc2c:4d01::1]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 173484b9-3a61-11f0-a2fb-13f23c93f187; Mon, 26 May 2025 20:41:53 +0200 (CEST) Received: from rochebonne.antioche.eu.org (rochebonne [10.0.0.1]) by chassiron.antioche.eu.org (8.18.1/8.16.1) with ESMTP id 54QIfpR1004279; Mon, 26 May 2025 20:41:51 +0200 (MEST) Received: by rochebonne.antioche.eu.org (Postfix, from userid 1210) id 4BDD31A4D0; Mon, 26 May 2025 20:41:16 +0200 (CEST) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 173484b9-3a61-11f0-a2fb-13f23c93f187 Date: Mon, 26 May 2025 20:41:16 +0200 From: Manuel Bouyer To: Andrew Cooper Cc: xen-devel@lists.xenproject.org Subject: Re: Xen 4.18.5 PV dbregs fail Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.4 (chassiron.antioche.eu.org [109.190.99.82]); Mon, 26 May 2025 20:41:51 +0200 (MEST) On Mon, May 26, 2025 at 07:06:04PM +0100, Andrew Cooper wrote: > On 26/05/2025 6:59 pm, Manuel Bouyer wrote: > > Hello, > > since I updated to Xen 4.18.5 (from 4.18.4), NetBSD's dbregs-related tests > > are failing. Only for PV; PVH and HVM guests are fine. They are > > failing for both 32bits and 64bits guests. > > > > I tracked it down to dr6 being 0xffff0ff0 after the trace trap, when at > > last one of the lower bits should be 1 (I think it's bit 0, from the code). > > > > I looked at the commit log between 4.18.4 and 4.18.5 but didn't see > > anything obvious. > > > > Any idea ? > > > > Have you got a link to the test in question? For example, dbregs_dr0_trap_code in https://cvsweb.netbsd.org/bsdweb.cgi/src/tests/lib/libc/sys/t_ptrace_x86_wait.h?rev=1.33;content-type=text%2Fplain What's failing is ATF_REQUIRE_EQ(info.psi_siginfo.si_code, TRAP_DBREG); I added printfs in the kernel to show the debug registers when the process traps, this is where the 0xffff0ff0 value comes from. -- Manuel Bouyer NetBSD: 26 ans d'experience feront toujours la difference --