Received: by 2002:ac0:a581:0:0:0:0:0 with SMTP id m1-v6csp884046imm; Fri, 29 Jun 2018 07:57:43 -0700 (PDT) X-Google-Smtp-Source: ADUXVKKaLUjmiDrIbKyOrvNDcd8aGyLw78otla24SObuRzUHz3o8tFcMkPmPUuK+pS3jOKWdYgUi X-Received: by 2002:a17:902:a5:: with SMTP id a34-v6mr15452318pla.80.1530284263645; Fri, 29 Jun 2018 07:57:43 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1530284263; cv=none; d=google.com; s=arc-20160816; b=tcBuNxFN3ikLkWLYAPYEpPsRa5Yum9HpoPUuHdTJ4X4iIazRm3Tci1WfGbTLmmR940 9jgB/EA8TcWDbybeF3k698ohstedUFEOX6ESsppsTXXa2TFDfVj6gs1NKl5UNuWXbX0W VABTwdD84ddhAT8cu338nkzB/LXiG7qnEd7S+ISwtK72aDlR54sZQoyK+BvRBnpll5x3 2+Ovvw62/FWmgqWPYfbebaOwTJm1VZuxFv0+SF03u9hqAuBKmJzKdD9+RjnrG6qQ/h9+ vtG+wfrvLJ9t0gJWyAhTVbf0Lt5UvfuODX7rcLVO7YFqeiKVER6dMrMk53Opnelp4d5V 2wkw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding :content-language:in-reply-to:mime-version:user-agent:date :message-id:autocrypt:openpgp:from:cc:references:to:subject :arc-authentication-results; bh=kdlsqwW8FdeoUj3PlpJ/5yttgK+/jaWrB0/7ajWn4qw=; b=TuS6OrUBO9/UTg5fW1vdB2avUfwPX1hjxPG4DH9xLbNCPS5wjfNQbxYpEHDr2Ilwlf +CazzJjcvKm4ia3OgPLkcHkl6s0i//LGfi53v1Y/3de3MdOMJNK7nxc0JLcocNXo14JK BoTNI7mEyklWKVB1+/Zk+IBWFnzkJVLcZX3akkAS6jR9p3XDTwy2Mhzyw4pwXvCDDzj+ /ZFEjnY8s+dckL2SqZPMNtNlP48FotWWxYsa/CkYmbDgzaVPhYnk98VkCg7RgkoWbLG+ aQvDFjYJul0U+Kq2pHd5wnwyrpIlG47fop5wMvlAi+GjHlwngOBG6rckjyYt9MKgs89w 8F4A== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id g5-v6si8493408pgp.91.2018.06.29.07.57.29; Fri, 29 Jun 2018 07:57:43 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755456AbeF2O4r (ORCPT + 99 others); Fri, 29 Jun 2018 10:56:47 -0400 Received: from mga12.intel.com ([192.55.52.136]:27776 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751234AbeF2O4p (ORCPT ); Fri, 29 Jun 2018 10:56:45 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 29 Jun 2018 07:56:45 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,285,1526367600"; d="scan'208";a="236631778" Received: from unknown (HELO [10.254.106.50]) ([10.254.106.50]) by orsmga005.jf.intel.com with ESMTP; 29 Jun 2018 07:56:40 -0700 Subject: Re: [PATCH v2 1/4] x86/split_lock: Enumerate #AC exception for split locked access feature To: Fenghua Yu , Thomas Gleixner , Ingo Molnar , H Peter Anvin References: <1530282807-66555-1-git-send-email-fenghua.yu@intel.com> <1530282807-66555-2-git-send-email-fenghua.yu@intel.com> Cc: Ashok Raj , Alan Cox , Peter Zijlstra , Rafael Wysocki , Tony Luck , Ravi V Shankar , linux-kernel , x86 From: Dave Hansen Openpgp: preference=signencrypt Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzShEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gPGRhdmVAc3I3MS5uZXQ+wsF7BBMBAgAlAhsDBgsJCAcDAgYVCAIJ CgsEFgIDAQIeAQIXgAUCTo3k0QIZAQAKCRBoNZUwcMmSsMO2D/421Xg8pimb9mPzM5N7khT0 2MCnaGssU1T59YPE25kYdx2HntwdO0JA27Wn9xx5zYijOe6B21ufrvsyv42auCO85+oFJWfE K2R/IpLle09GDx5tcEmMAHX6KSxpHmGuJmUPibHVbfep2aCh9lKaDqQR07gXXWK5/yU1Dx0r VVFRaHTasp9fZ9AmY4K9/BSA3VkQ8v3OrxNty3OdsrmTTzO91YszpdbjjEFZK53zXy6tUD2d e1i0kBBS6NLAAsqEtneplz88T/v7MpLmpY30N9gQU3QyRC50jJ7LU9RazMjUQY1WohVsR56d ORqFxS8ChhyJs7BI34vQusYHDTp6PnZHUppb9WIzjeWlC7Jc8lSBDlEWodmqQQgp5+6AfhTD kDv1a+W5+ncq+Uo63WHRiCPuyt4di4/0zo28RVcjtzlGBZtmz2EIC3vUfmoZbO/Gn6EKbYAn rzz3iU/JWV8DwQ+sZSGu0HmvYMt6t5SmqWQo/hyHtA7uF5Wxtu1lCgolSQw4t49ZuOyOnQi5 f8R3nE7lpVCSF1TT+h8kMvFPv3VG7KunyjHr3sEptYxQs4VRxqeirSuyBv1TyxT+LdTm6j4a mulOWf+YtFRAgIYyyN5YOepDEBv4LUM8Tz98lZiNMlFyRMNrsLV6Pv6SxhrMxbT6TNVS5D+6 UorTLotDZKp5+M7BTQRUY85qARAAsgMW71BIXRgxjYNCYQ3Xs8k3TfAvQRbHccky50h99TUY sqdULbsb3KhmY29raw1bgmyM0a4DGS1YKN7qazCDsdQlxIJp9t2YYdBKXVRzPCCsfWe1dK/q 66UVhRPP8EGZ4CmFYuPTxqGY+dGRInxCeap/xzbKdvmPm01Iw3YFjAE4PQ4hTMr/H76KoDbD cq62U50oKC83ca/PRRh2QqEqACvIH4BR7jueAZSPEDnzwxvVgzyeuhwqHY05QRK/wsKuhq7s UuYtmN92Fasbxbw2tbVLZfoidklikvZAmotg0dwcFTjSRGEg0Gr3p/xBzJWNavFZZ95Rj7Et db0lCt0HDSY5q4GMR+SrFbH+jzUY/ZqfGdZCBqo0cdPPp58krVgtIGR+ja2Mkva6ah94/oQN lnCOw3udS+Eb/aRcM6detZr7XOngvxsWolBrhwTQFT9D2NH6ryAuvKd6yyAFt3/e7r+HHtkU kOy27D7IpjngqP+b4EumELI/NxPgIqT69PQmo9IZaI/oRaKorYnDaZrMXViqDrFdD37XELwQ gmLoSm2VfbOYY7fap/AhPOgOYOSqg3/Nxcapv71yoBzRRxOc4FxmZ65mn+q3rEM27yRztBW9 AnCKIc66T2i92HqXCw6AgoBJRjBkI3QnEkPgohQkZdAb8o9WGVKpfmZKbYBo4pEAEQEAAcLB XwQYAQIACQUCVGPOagIbDAAKCRBoNZUwcMmSsJeCEACCh7P/aaOLKWQxcnw47p4phIVR6pVL e4IEdR7Jf7ZL00s3vKSNT+nRqdl1ugJx9Ymsp8kXKMk9GSfmZpuMQB9c6io1qZc6nW/3TtvK pNGz7KPPtaDzvKA4S5tfrWPnDr7n15AU5vsIZvgMjU42gkbemkjJwP0B1RkifIK60yQqAAlT YZ14P0dIPdIPIlfEPiAWcg5BtLQU4Wg3cNQdpWrCJ1E3m/RIlXy/2Y3YOVVohfSy+4kvvYU3 lXUdPb04UPw4VWwjcVZPg7cgR7Izion61bGHqVqURgSALt2yvHl7cr68NYoFkzbNsGsye9ft M9ozM23JSgMkRylPSXTeh5JIK9pz2+etco3AfLCKtaRVysjvpysukmWMTrx8QnI5Nn5MOlJj 1Ov4/50JY9pXzgIDVSrgy6LYSMc4vKZ3QfCY7ipLRORyalFDF3j5AGCMRENJjHPD6O7bl3Xo 4DzMID+8eucbXxKiNEbs21IqBZbbKdY1GkcEGTE7AnkA3Y6YB7I/j9mQ3hCgm5muJuhM/2Fr OPsw5tV/LmQ5GXH0JQ/TZXWygyRFyyI2FqNTx4WHqUn3yFj8rwTAU1tluRUYyeLy0ayUlKBH ybj0N71vWO936MqP6haFERzuPAIpxj2ezwu0xb1GjTk4ynna6h5GjnKgdfOWoRtoWndMZxbA z5cecg== Message-ID: Date: Fri, 29 Jun 2018 07:56:40 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <1530282807-66555-2-git-send-email-fenghua.yu@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/29/2018 07:33 AM, Fenghua Yu wrote: > +/* Detect feature of #AC for split lock by probing bit 29 in MSR_TEST_CTL. */ > +void detect_ac_split_lock(void) > +{ > + u64 val, orig_val; > + int ret; > + > + /* Attempt to read the MSR. If the MSR doesn't exist, reading fails. */ > + ret = rdmsrl_safe(MSR_TEST_CTL, &val); > + if (ret) > + return; This is a bit fast and loose with how the feature is detected, which might be OK, but can we call out why we are doing this, please? Is this MSR not really model-specific? Is it OK to go poking at it on all x86 variants? Or, do we at _least_ need a check for Intel cpus in here?