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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9F6C3C433FE for ; Thu, 29 Sep 2022 16:28:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236275AbiI2Q1y (ORCPT ); Thu, 29 Sep 2022 12:27:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57896 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236173AbiI2Q1S (ORCPT ); Thu, 29 Sep 2022 12:27:18 -0400 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 09AF8149D16 for ; Thu, 29 Sep 2022 09:26:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1664468801; x=1696004801; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=Omj4s+TYR9HP2Mo9RreV0sozGn4K2bgnUI3UDLk6NsI=; b=dylUSpaF4v2UO6L7bNUeCTv4aFJc/knrk04/qGVB1N1svNo+oRiHD4MD 2AwnUgA/i5QwJQh97u+/rwe/Mb6E+vkSo3GHZXHjNNHDTjrCSPfVpwAA+ tuDCtSgRBe1EMitpPXtnj5xTEtgBVDq9tqCbLGJxku8SVyRw8D3C1m/3J VLmWbhFs7YptPPKRvYHMOyqfySv/YSyg4lrXVdQ+Z6N+UCZrT34HMFT2g eTTe/byIEWxfEHzFIHhUDFWin6TUcEsnTmjBILKwELHLq5zD6S7GhxqOK wchoSLsYyeWJLTYfPdRsuPG5Q5PaPx108xdzL3qv85rA6/Hq2XYILR/Xi A==; X-IronPort-AV: E=McAfee;i="6500,9779,10485"; a="289112364" X-IronPort-AV: E=Sophos;i="5.93,355,1654585200"; d="scan'208";a="289112364" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Sep 2022 09:26:40 -0700 X-IronPort-AV: E=McAfee;i="6500,9779,10485"; a="867455516" X-IronPort-AV: E=Sophos;i="5.93,355,1654585200"; d="scan'208";a="867455516" Received: from ticela-or-324.amr.corp.intel.com (HELO [10.251.13.128]) ([10.251.13.128]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Sep 2022 09:26:39 -0700 Message-ID: Date: Thu, 29 Sep 2022 09:26:38 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH] x86/split_lock: Restore warn mode (and add a new one) to avoid userspace regression Content-Language: en-US To: "Guilherme G. Piccoli" , tony.luck@intel.com, tglx@linutronix.de, linux-kernel@vger.kernel.org, x86@kernel.org Cc: mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, luto@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, Fenghua Yu , Joshua Ashton , Paul Gofman , Pavel Machek , Pierre-Loup Griffais , Melissa Wen References: <20220928142109.150263-1-gpiccoli@igalia.com> <24f31510-5b33-ada5-9f0e-117420403e8c@intel.com> <1c742ae1-98cb-a5c1-ba3f-5e79b8861f0b@igalia.com> <7917fde2-a381-5404-c5ae-6ffd433f85ec@igalia.com> From: Dave Hansen In-Reply-To: <7917fde2-a381-5404-c5ae-6ffd433f85ec@igalia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/29/22 08:30, Guilherme G. Piccoli wrote: >> How about we give it a few weeks and see if the current behavior impacts >> anyone else? Maybe the best route will be more clear then. > ...I disagree in just letting it fly for weeks with all players of God > of War 2 running modern Intel chips unable to play in 5.19+ because of > this change. Let's be precise here, though. It isn't that folks can't play. It's that we *intentionally* put something in place that kept them from playing. They can play just fine after disabling split lock detection. > Certainly we have more games/applications that are impacted, I just > don't think we should wait on having 3 userspace breakages reported, > for example, to take an action - why should gamers live with this for > an arbitrary amount of time, until others report more issues? They don't have to live with it. They can turn it off. That's why the command-line disable is there. The real question in my head is whether the misery is intentional or not. Is breaking games what folks _intended_ with split_lock_detect=warn? Or, is this a more severe penalty than we expected and maybe we should back off for the default?