Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759902AbcJ1J4h (ORCPT ); Fri, 28 Oct 2016 05:56:37 -0400 Received: from mga07.intel.com ([134.134.136.100]:13169 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759063AbcJ1J4e (ORCPT ); Fri, 28 Oct 2016 05:56:34 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,557,1473145200"; d="scan'208";a="1077138894" Date: Fri, 28 Oct 2016 17:55:49 +0800 From: He Chen To: Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, Radim =?utf-8?B?S3LEjW3DocWZ?= , Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , Luwei Kang , Piotr Luc Subject: Re: [PATCH] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS features to kvm guest Message-ID: <20161028095549.GA9295@he> References: <1477645960-6898-1-git-send-email-he.chen@linux.intel.com> <98097397-f1a5-c0b0-0620-31d07b715272@redhat.com> <20161028094645.GA8148@he> <462c1f5a-1b91-7d03-d192-23d778ae54af@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <462c1f5a-1b91-7d03-d192-23d778ae54af@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1956 Lines: 56 On Fri, Oct 28, 2016 at 11:54:13AM +0200, Paolo Bonzini wrote: > > > On 28/10/2016 11:46, He Chen wrote: > > On Fri, Oct 28, 2016 at 11:31:05AM +0200, Paolo Bonzini wrote: > >> > >> > >> On 28/10/2016 11:12, He Chen wrote: > >>> The spec can be found in Intel Software Developer Manual or in > >>> Instruction Set Extensions Programming Reference. > >>> > >>> Signed-off-by: Luwei Kang > >>> Signed-off-by: He Chen > >>> --- > >>> arch/x86/kvm/cpuid.c | 7 ++++++- > >>> 1 file changed, 6 insertions(+), 1 deletion(-) > >>> > >>> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > >>> index afa7bbb..328b169 100644 > >>> --- a/arch/x86/kvm/cpuid.c > >>> +++ b/arch/x86/kvm/cpuid.c > >>> @@ -376,6 +376,10 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, > >>> /* cpuid 7.0.ecx*/ > >>> const u32 kvm_cpuid_7_0_ecx_x86_features = F(PKU) | 0 /*OSPKE*/; > >>> > >>> + /* cpuid 7.0.edx*/ > >>> + const u32 kvm_cpuid_7_0_edx_x86_features = > >>> + 0x4 /* AVX512-4VNNIW */ | 0x8 /* AVX512-4FMAPS */; > >> > >> Please define the new features in cpufeature.h first. > >> > > These 2 new features defined as scattered features in kernel. > > In cpufeature.h, there are: > > #define X86_FEATURE_AVX512_4VNNIW (7*32+16) > > #define X86_FEATURE_AVX512_4FMAPS (7*32+17) > > > > Please see disscusion here: > > https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1250183.html > > Uff, that sucks. :( I'd agree with hpa's position in that thread. > > Please do something like > > /* These are scattered features in cpufeature.h. */ > #define KVM_CPUID_BIT_AVX512_4VNNIW 2 > #define KVM_CPUID_BIT_AVX512_4FMAPS 3 > #define KF(x) bit(KVM_CPUID_BIT_##x) > > and then > > const u32 kvm_cpuid_7_0_edx_x86_features = > KF(AVX512_4VNNIW) | KF(AVX512_4FMAPS) > > I'll think of a trick to avoid using F for scattered features... > Appreciate it :-)