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 D4A6FC433F5 for ; Wed, 1 Dec 2021 19:12:55 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.236207.409709 (Exim 4.92) (envelope-from ) id 1msV22-0008Ru-2i; Wed, 01 Dec 2021 19:12:42 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 236207.409709; Wed, 01 Dec 2021 19:12:42 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1msV21-0008Rn-W4; Wed, 01 Dec 2021 19:12:41 +0000 Received: by outflank-mailman (input) for mailman id 236207; Wed, 01 Dec 2021 19:12:40 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1msV20-0008Rh-Lp for xen-devel@lists.xenproject.org; Wed, 01 Dec 2021 19:12:40 +0000 Received: from ppsw-33.csi.cam.ac.uk (ppsw-33.csi.cam.ac.uk [131.111.8.133]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id a6da67bc-52da-11ec-b1df-f38ee3fbfdf7; Wed, 01 Dec 2021 20:12:39 +0100 (CET) Received: from hades.srcf.societies.cam.ac.uk ([131.111.179.67]:50700) by ppsw-33.csi.cam.ac.uk (ppsw.cam.ac.uk [131.111.8.137]:25) with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) id 1msV1z-000SHc-he (Exim 4.95) (return-path ); Wed, 01 Dec 2021 19:12:39 +0000 Received: from [192.168.1.10] (host-92-12-61-86.as13285.net [92.12.61.86]) (Authenticated sender: amc96) by hades.srcf.societies.cam.ac.uk (Postfix) with ESMTPSA id 437E41FD7A; Wed, 1 Dec 2021 19:12:39 +0000 (GMT) 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: a6da67bc-52da-11ec-b1df-f38ee3fbfdf7 X-Cam-AntiVirus: no malware found X-Cam-ScannerInfo: https://help.uis.cam.ac.uk/email-scanner-virus Message-ID: <352d554d-dbea-e7b9-e499-91517ffc17c3@srcf.net> Date: Wed, 1 Dec 2021 19:12:39 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.2 Subject: Re: [PATCH 4/4] x86/ucode: Use altcall, and __initdata_cf_clobber Content-Language: en-GB To: Jan Beulich , Andrew Cooper Cc: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Wei Liu , Xen-devel References: <20211126212258.7550-1-andrew.cooper3@citrix.com> <20211126212258.7550-5-andrew.cooper3@citrix.com> <8943376d-b6cc-6c04-c4aa-c8d30800dfca@suse.com> From: Andrew Cooper In-Reply-To: <8943376d-b6cc-6c04-c4aa-c8d30800dfca@suse.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 01/12/2021 08:23, Jan Beulich wrote: > On 26.11.2021 22:22, Andrew Cooper wrote: >> Microcode loading is not a fastpath, but there are control flow security >> benefits from using altcall()'s hardening side effect. >> >> Convert the existing microcode_ops pointer into a __read_mostly structure, and >> move {amd,intel}_ucode_ops into __initdata_cf_clobber. >> >> Signed-off-by: Andrew Cooper > Again subject to the resolution of the const aspect and perhaps > with __read_mostly converted to __ro_after_init (assuming its > introduction goes in first) > Reviewed-by: Jan Beulich Thanks. Given how simple __ro_after_init was, it would be preferable to get that in first, than to go around patching these a second time. ~Andrew