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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT 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 CA64BC31E46 for ; Wed, 12 Jun 2019 17:13:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A9D5C215EA for ; Wed, 12 Jun 2019 17:13:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392141AbfFLRN2 (ORCPT ); Wed, 12 Jun 2019 13:13:28 -0400 Received: from mga12.intel.com ([192.55.52.136]:14682 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390335AbfFLRN2 (ORCPT ); Wed, 12 Jun 2019 13:13:28 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Jun 2019 10:13:27 -0700 X-ExtLoop1: 1 Received: from romley-ivt3.sc.intel.com ([172.25.110.60]) by fmsmga008.fm.intel.com with ESMTP; 12 Jun 2019 10:13:27 -0700 Date: Wed, 12 Jun 2019 10:04:04 -0700 From: Fenghua Yu To: Sean Christopherson Cc: Borislav Petkov , Thomas Gleixner , Ingo Molnar , H Peter Anvin , Ravi V Shankar , linux-kernel , x86 Subject: Re: [RFC PATCH] x86/cpufeatures: Enumerate new AVX512 bfloat16 instructions Message-ID: <20190612170404.GF180343@romley-ivt3.sc.intel.com> References: <1560186158-174788-1-git-send-email-fenghua.yu@intel.com> <20190610192026.GI5488@zn.tnic> <20190611181920.GC180343@romley-ivt3.sc.intel.com> <20190611194701.GJ31772@zn.tnic> <20190612033259.GE180343@romley-ivt3.sc.intel.com> <20190612040259.GC32652@zn.tnic> <20190612141049.GA20308@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190612141049.GA20308@linux.intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 12, 2019 at 07:10:49AM -0700, Sean Christopherson wrote: > On Wed, Jun 12, 2019 at 06:02:59AM +0200, Borislav Petkov wrote: > > On Tue, Jun 11, 2019 at 08:32:59PM -0700, Fenghua Yu wrote: > > > Currently KVM doesn't simulate scattered features (the ones in CPUID_LNX_* > > > in cpuid_leafs) as reverse_cpuid[] doesn't contain CPUID_LNX_*. > > > > 43500e6f294d ("x86/cpufeatures: Remove get_scattered_cpuid_leaf()") > > > > > After the X86_FEATURES_CQM_* features are changed to scattered features, > > > they will not be simulated by KVM any more as CPUID_F_0_EDX and CPUID_F_1_EDX > > > are removed. > > > > Does KVM even support resctrl? I doubt only exporting a couple of CPUID > > bits into the guest is enough... > > KVM doesn't support resctrl. Moving X86_FEATURES_CQM_* to a scattered > leaf won't affect KVM. > > > > Should patch #1 simulate X86_FEATURE_CQM_* in KVM? Or let KVM guys handle > > > the scattered features? > > > > Right, the scattered thing was removed as KVM didn't need it, > > apparently, see above. > > Let KVM people deal with it, in the unlikely event someone adds resctrl > support to KVM. Thank you for your insight, Boris and Sean! -Fenghua