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 BA0CFC433EF for ; Thu, 16 Dec 2021 16:42:03 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.248087.427887 (Exim 4.92) (envelope-from ) id 1mxtpK-0004YI-QD; Thu, 16 Dec 2021 16:41:54 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 248087.427887; Thu, 16 Dec 2021 16:41:54 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mxtpK-0004YA-N9; Thu, 16 Dec 2021 16:41:54 +0000 Received: by outflank-mailman (input) for mailman id 248087; Thu, 16 Dec 2021 16:41:53 +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 1mxtpJ-00044L-1f for xen-devel@lists.xenproject.org; Thu, 16 Dec 2021 16:41:53 +0000 Received: from ppsw-32.csi.cam.ac.uk (ppsw-32.csi.cam.ac.uk [131.111.8.132]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id 11824273-5e8f-11ec-85d3-df6b77346a89; Thu, 16 Dec 2021 17:41:51 +0100 (CET) Received: from hades.srcf.societies.cam.ac.uk ([131.111.179.67]:44476) by ppsw-32.csi.cam.ac.uk (ppsw.cam.ac.uk [131.111.8.136]:25) with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) id 1mxtpG-000IYz-1v (Exim 4.95) (return-path ); Thu, 16 Dec 2021 16:41:50 +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 566351FB21; Thu, 16 Dec 2021 16:41:50 +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: 11824273-5e8f-11ec-85d3-df6b77346a89 X-Cam-AntiVirus: no malware found X-Cam-ScannerInfo: https://help.uis.cam.ac.uk/email-scanner-virus Message-ID: <8e648c7b-33a6-642c-e4ff-78f17a35dbe3@srcf.net> Date: Thu, 16 Dec 2021 16:41:50 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [PATCH v2 1/4] x86/cpuid: Split dom0 handling out of init_domain_cpuid_policy() Content-Language: en-GB To: Jan Beulich , Andrew Cooper Cc: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Wei Liu , Xen-devel References: <20211215222115.6829-1-andrew.cooper3@citrix.com> <20211215222115.6829-2-andrew.cooper3@citrix.com> From: Andrew Cooper In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 16/12/2021 16:38, Jan Beulich wrote: > On 15.12.2021 23:21, Andrew Cooper wrote: >> To implement dom0-cpuid= support, the special cases would need extending. >> However there is already a problem with late hwdom where the special cases >> override toolstack settings, which is unintended and poor behaviour. >> >> Introduce a new init_dom0_cpuid_policy() for the purpose, moving the ITSC and >> ARCH_CAPS logic. The is_hardware_domain() can be dropped, and for now there >> is no need to rerun recalculate_cpuid_policy(); this is a relatively expensive >> operation, and will become more-so over time. > Would you mind leaving it there in a commented out form, hinting at when > it may need re-enabling? Leave what?  The recalculate_cpuid_policy()?  That comes back in later in the series. ~Andrew > >> Rearrange the logic in create_dom0() to make room for a call to >> init_dom0_cpuid_policy(). The AMX plans for having variable sized XSAVE >> states require that modifications to the policy happen before vCPUs are >> created. >> >> Additionally, factor out domid into a variable so we can be slightly more >> correct in the case of a failure, and also print the error from >> domain_create(). This will at least help distinguish -EINVAL from -ENOMEM. >> >> No practical change in behaviour. >> >> Signed-off-by: Andrew Cooper > Preferably with said comment added: > Reviewed-by: Jan Beulich > > Jan > >