From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752573AbdK3MUg (ORCPT ); Thu, 30 Nov 2017 07:20:36 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35284 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752457AbdK3MUb (ORCPT ); Thu, 30 Nov 2017 07:20:31 -0500 Subject: Re: [PATCH v3 7/9] KVM: x86: Implement Intel Processor Trace MSRs read/write To: Luwei Kang , kvm@vger.kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, rkrcmar@redhat.com, linux-kernel@vger.kernel.org, joro@8bytes.org, Chao Peng References: <1511814242-12949-1-git-send-email-luwei.kang@intel.com> <1511814242-12949-8-git-send-email-luwei.kang@intel.com> From: Paolo Bonzini Message-ID: <3cfad210-6633-66cf-0276-95d4ca1af273@redhat.com> Date: Thu, 30 Nov 2017 13:20:27 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <1511814242-12949-8-git-send-email-luwei.kang@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Thu, 30 Nov 2017 12:20:31 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27/11/2017 21:24, Luwei Kang wrote: > + case MSR_IA32_RTIT_ADDR0_A ... MSR_IA32_RTIT_ADDR3_B: { > + u32 eax, ebx, ecx, edx; > + > + cpuid_count(0x14, 1, &eax, &ebx, &ecx, &edx); Please cache the cpuid_count result, or do the cpuid_count after testing vmx_pt_supported() (which you can use instead of going through kvm_x86_ops). Thanks, Paolo > + if (!kvm_x86_ops->pt_supported() || msrs_to_save[i] - > + MSR_IA32_RTIT_ADDR0_A >= (eax & 0x7)) > + continue; > + break;