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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id 3A1F5C433EF for ; Tue, 12 Jun 2018 21:08:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ECD0F2086E for ; Tue, 12 Jun 2018 21:08:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ECD0F2086E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=maciej.szmigiero.name Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934187AbeFLVIm (ORCPT ); Tue, 12 Jun 2018 17:08:42 -0400 Received: from vps-vb.mhejs.net ([37.28.154.113]:36886 "EHLO vps-vb.mhejs.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932985AbeFLVIk (ORCPT ); Tue, 12 Jun 2018 17:08:40 -0400 Received: by vps-vb.mhejs.net with esmtps (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.90_1) (envelope-from ) id 1fSqWl-0007sg-UO; Tue, 12 Jun 2018 23:08:31 +0200 Subject: Re: [PATCH v6 8/8] x86/microcode/AMD: Don't scan past the CPU equivalence table data To: Borislav Petkov Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org References: <04a252b1e06673b8a1f62196093d0573d302fc1b.1526767245.git.mail@maciej.szmigiero.name> <20180605085506.GB27701@nazgul.tnic> From: "Maciej S. Szmigiero" Openpgp: preference=signencrypt Autocrypt: addr=mail@maciej.szmigiero.name; prefer-encrypt=mutual; keydata= xsFNBFpGusUBEADXUMM2t7y9sHhI79+2QUnDdpauIBjZDukPZArwD+sDlx5P+jxaZ13XjUQc 6oJdk+jpvKiyzlbKqlDtw/Y2Ob24tg1g/zvkHn8AVUwX+ZWWewSZ0vcwp7u/LvA+w2nJbIL1 N0/QUUdmxfkWTHhNqgkNX5hEmYqhwUPozFR0zblfD/6+XFR7VM9yT0fZPLqYLNOmGfqAXlxY m8nWmi+lxkd/PYqQQwOq6GQwxjRFEvSc09m/YPYo9hxh7a6s8hAP88YOf2PD8oBB1r5E7KGb Fv10Qss4CU/3zaiyRTExWwOJnTQdzSbtnM3S8/ZO/sL0FY/b4VLtlZzERAraxHdnPn8GgxYk oPtAqoyf52RkCabL9dsXPWYQjkwG8WEUPScHDy8Uoo6imQujshG23A99iPuXcWc/5ld9mIo/ Ee7kN50MOXwS4vCJSv0cMkVhh77CmGUv5++E/rPcbXPLTPeRVy6SHgdDhIj7elmx2Lgo0cyh uyxyBKSuzPvb61nh5EKAGL7kPqflNw7LJkInzHqKHDNu57rVuCHEx4yxcKNB4pdE2SgyPxs9 9W7Cz0q2Hd7Yu8GOXvMfQfrBiEV4q4PzidUtV6sLqVq0RMK7LEi0RiZpthwxz0IUFwRw2KS/ 9Kgs9LmOXYimodrV0pMxpVqcyTepmDSoWzyXNP2NL1+GuQtaTQARAQABzTBNYWNpZWogUy4g U3ptaWdpZXJvIDxtYWlsQG1hY2llai5zem1pZ2llcm8ubmFtZT7CwZQEEwEIAD4WIQRyeg1N 257Z9gOb7O+Ef143kM4JdwUCWka6xQIbAwUJA8JnAAULCQgHAgYVCgkICwIEFgIDAQIeAQIX gAAKCRCEf143kM4Jdx4+EACwi1bXraGxNwgFj+KI8T0Xar3fYdaOF7bb7cAHllBCPQkutjnx 8SkYxqGvSNbBhGtpL1TqAYLB1Jr+ElB8qWEV6bJrffbRmsiBPORAxMfu8FF+kVqCYZs3nbku XNzmzp6R/eii40S+XySiscmpsrVQvz7I+xIIYdC0OTUu0Vl3IHf718GBYSD+TodCazEdN96k p9uD9kWNCU1vnL7FzhqClhPYLjPCkotrWM4gBNDbRiEHv1zMXb0/jVIR/wcDIUv6SLhzDIQn Lhre8LyKwid+WQxq7ZF0H+0VnPf5q56990cEBeB4xSyI+tr47uNP2K1kmW1FPd5q6XlIlvh2 WxsG6RNphbo8lIE6sd7NWSY3wXu4/R1AGdn2mnXKMp2O9039ewY6IhoeodCKN39ZR9LNld2w Dp0MU39LukPZKkVtbMEOEi0R1LXQAY0TQO//0IlAehfbkkYv6IAuNDd/exnj59GtwRfsXaVR Nw7XR/8bCvwU4svyRqI4luSuEiXvM9rwDAXbRKmu+Pk5h+1AOV+KjKPWCkBEHaASOxuApouQ aPZw6HDJ3fdFmN+m+vNcRPzST30QxGrXlS5GgY6CJ10W9gt/IJrFGoGxGxYjj4WzO97Rg6Mq WMa7wMPPNcnX5Nc/b8HW67Jhs3trj0szq6FKhqBsACktOU4g/ksV8eEtnM7AzQRaRrwiAQwA xnVmJqeP9VUTISps+WbyYFYlMFfIurl7tzK74bc67KUBp+PHuDP9p4ZcJUGC3UZJP85/GlUV dE1NairYWEJQUB7bpogTuzMI825QXIB9z842HwWfP2RW5eDtJMeujzJeFaUpmeTG9snzaYxY N3r0TDKj5dZwSIThIMQpsmhH2zylkT0jH7kBPxb8IkCQ1c6wgKITwoHFjTIO0B75U7bBNSDp XUaUDvd6T3xd1Fz57ujAvKHrZfWtaNSGwLmUYQAcFvrKDGPB5Z3ggkiTtkmW3OCQbnIxGJJw /+HefYhB5/kCcpKUQ2RYcYgCZ0/WcES1xU5dnNe4i0a5gsOFSOYCpNCfTHttVxKxZZTQ/rxj XwTuToXmTI4Nehn96t25DHZ0t9L9UEJ0yxH2y8Av4rtf75K2yAXFZa8dHnQgCkyjA/gs0ujG wD+Gs7dYQxP4i+rLhwBWD3mawJxLxY0vGwkG7k7npqanlsWlATHpOdqBMUiAR22hs02FikAo iXNgWTy7ABEBAAHCwXwEGAEIACYWIQRyeg1N257Z9gOb7O+Ef143kM4JdwUCWka8IgIbDAUJ A8JnAAAKCRCEf143kM4Jd9nXD/9jstJU6L1MLyr/ydKOnY48pSlZYgII9rSnFyLUHzNcW2c/ qw9LPMlDcK13tiVRQgKT4W+RvsET/tZCQcap2OF3Z6vd1naTur7oJvgvVM5lVhUia2O60kEZ XNlMLFwLSmGXhaAXNBySpzN2xStSLCtbK58r7Vf9QS0mR0PGU2v68Cb8fFWcYu2Yzn3RXf0Y dIVWvaQG9whxZq5MdJm5dknfTcCG+MtmbP/DnpQpjAlgVmDgMgYTBW1W9etU36YW0pTqEYuv 6cmRgSAKEDaYHhFLTR1+lLJkp5fFo3Sjm7XqmXzfSv9JGJGMKzoFOMBoLYv+VFnMoLX5UJAs 0JyFqFY2YxGyLd4J103NI/ocqQeU0TVvOZGVkENPSxIESnbxPghsEC0MWEbGsvqA8FwvU7Xf GhZPYzTRf7CndDnezEA69EhwpZXKs4CvxbXo5PDTv0OWzVaAWqq8s8aTMJWWAhvobFozJ63z afYHkuEjMo0Xps3o3uvKg7coooH521nNsv4ci+KeBq3mgMCRAy0g/Ef+Ql7mt900RCBHu4tk tOhPc3J1ep/e2WAJ4ngUqJhilzyCJnzVJ4cT79VK/uPtlfUCZdUz+jTC88TmP1p5wlucS31k Thy/CV4cqDFB8yzEujTSiRzd7neG3sH0vcxBd69uvSxLZPLGID840k0v5sftPA== Message-ID: <957d6884-f24b-0d40-7584-d4386d05af21@maciej.szmigiero.name> Date: Tue, 12 Jun 2018 23:08:31 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180605085506.GB27701@nazgul.tnic> 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 05.06.2018 10:55, Borislav Petkov wrote: > On Sun, May 20, 2018 at 12:07:22AM +0200, Maciej S. Szmigiero wrote: >> Currently, the code scanning a CPU equivalence table read from a microcode >> container file assumes that it actually contains a terminating zero entry, >> but if does not then the code will continue the scan past its valid data. >> >> For the late loader this can be improved by always appending a terminating >> zero entry to such table when loading it. >> This way we don't need an extra global variable for holding the table size >> and we don't have to reject such incomplete tables (for backward >> compatibility with the existing code which didn't do so). >> >> For the early loader, since we can't allocate memory and have to work >> in-place, let's pass an explicit size of this table to its scanning >> functions so they will know when to stop. > > I don't like the difference between early and late here. Just pass > explicit size to the late loader too. That was the solution before this patch series version (6) - there was a variable holding the CPU equivalence table size for the late loader, but you didn't like it:> Instead of adding yet another global var which needs handling too, > and touching so many places, just do all checks and preparations in > install_equiv_cpu_table() so that the rest of the code can get what it > expects: terminating zero entry and proper size. And we would need to hold this explicit size somewhere since the table scanning function in the late loader is on a different call path than microcode file parsing. Maciej