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=-12.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1D1FEC433ED for ; Thu, 22 Apr 2021 08:32:13 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id AC5E161426 for ; Thu, 22 Apr 2021 08:32:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AC5E161426 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.115196.219667 (Exim 4.92) (envelope-from ) id 1lZUki-0005me-FZ; Thu, 22 Apr 2021 08:32:00 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 115196.219667; Thu, 22 Apr 2021 08:32:00 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lZUki-0005mX-C9; Thu, 22 Apr 2021 08:32:00 +0000 Received: by outflank-mailman (input) for mailman id 115196; Thu, 22 Apr 2021 08:31:58 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lZUkg-0005mS-TH for xen-devel@lists.xenproject.org; Thu, 22 Apr 2021 08:31:58 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 664c74df-573b-489b-bd76-7ebe9fee989e; Thu, 22 Apr 2021 08:31:58 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 3D383AD80; Thu, 22 Apr 2021 08:31:57 +0000 (UTC) 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: 664c74df-573b-489b-bd76-7ebe9fee989e X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1619080317; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Itmj1dp0jX2qjPeM0M8JlSoAYgWKoD9M1ycMH63OQYY=; b=F37WVmwdpCK+X/rQmCbQWirxjRYK9Ed2TOa8K/JvUovkrHiGQKuUHDTqL7asM0CnnkHSdn uUyqCgdw3Gg9brY1auKlhPg/2IP1zzEwyGNRcytvGz+AquRqcKqZzyM5oA/Q+UprnhUu65 zwUs3AMkNPch8cpw5EM08qTUmnjM8Hs= Subject: Re: [PATCH v2 14/21] libs/guest: introduce helper to check cpu policy compatibility To: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Andrew Cooper Cc: Ian Jackson , Wei Liu , xen-devel@lists.xenproject.org References: <20210413140140.73690-1-roger.pau@citrix.com> <20210413140140.73690-15-roger.pau@citrix.com> From: Jan Beulich Message-ID: <9349102e-7019-c6c3-3830-6374b47f314b@suse.com> Date: Thu, 22 Apr 2021 10:31:57 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit On 22.04.2021 10:22, Roger Pau Monné wrote: > On Wed, Apr 14, 2021 at 03:36:54PM +0200, Jan Beulich wrote: >> On 13.04.2021 16:01, Roger Pau Monne wrote: >>> --- a/tools/libs/guest/xg_cpuid_x86.c >>> +++ b/tools/libs/guest/xg_cpuid_x86.c >>> @@ -925,3 +925,22 @@ int xc_cpu_policy_update_msrs(xc_interface *xch, xc_cpu_policy_t policy, >>> >>> return rc; >>> } >>> + >>> +bool xc_cpu_policy_is_compatible(xc_interface *xch, const xc_cpu_policy_t host, >>> + const xc_cpu_policy_t guest) >>> +{ >>> + struct cpu_policy_errors err = INIT_CPU_POLICY_ERRORS; >>> + struct cpu_policy h = { &host->cpuid, &host->msr }; >>> + struct cpu_policy g = { &guest->cpuid, &guest->msr }; >>> + int rc = x86_cpu_policies_are_compatible(&h, &g, &err); >>> + >>> + if ( !rc ) >>> + return true; >>> + >>> + if ( err.leaf != -1 ) >>> + ERROR("Leaf %#x subleaf %#x is not compatible", err.leaf, err.subleaf); >>> + if ( err.msr != -1 ) >>> + ERROR("MSR index %#x is not compatible", err.msr); >> >> Personally I'm against making assumptions like these ones about what >> (in this case) INIT_CPU_POLICY_ERRORS actually expands to (i.e. three >> times -1). I can see how alternatives to this are quickly going to >> get ugly, so I'll leave it to others to judge. > > Would you like me to define a separate POLICY_ERROR? ie: > > #define INIT_CPU_POLICY_ERROR -1 > #define INIT_CPU_POLICY_ERRORS { INIT_CPU_POLICY_ERROR, \ > INIT_CPU_POLICY_ERROR, \ > INIT_CPU_POLICY_ERROR } I would prefer this; I'm not sure (nit: properly parenthesized) -1 is the value to use though, considering the fields are unsigned. I wonder what Andrew thinks, as he did introduce all of this. > We already have a bunch of open coded -1 checks anyway, but might > prevent new ones from appearing. Indeed. Jan