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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 C409DC5DF60 for ; Wed, 6 Nov 2019 01:01:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7C2AF2087E for ; Wed, 6 Nov 2019 01:01:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730125AbfKFBBW (ORCPT ); Tue, 5 Nov 2019 20:01:22 -0500 Received: from mga09.intel.com ([134.134.136.24]:35686 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729614AbfKFBBV (ORCPT ); Tue, 5 Nov 2019 20:01:21 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Nov 2019 17:01:21 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,272,1569308400"; d="scan'208";a="205687897" Received: from cqiang-mobl.ccr.corp.intel.com (HELO [10.239.198.110]) ([10.239.198.110]) by orsmga006.jf.intel.com with ESMTP; 05 Nov 2019 17:01:18 -0800 Subject: Re: [PATCH] KVM: X86: Dynamically allocating MSR number lists(msrs_to_save[], emulated_msrs[], msr_based_features[]) To: Paolo Bonzini , Xiaoyao Li , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Sean Christopherson , Vitaly Kuznetsov , Jim Mattson , Joerg Roedel Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20191105092031.8064-1-chenyi.qiang@intel.com> <4a5fd5b4-64b7-726a-57a5-a5c669ce84f6@redhat.com> <477da390-4bdb-c25d-24b1-5b57c3bf78bb@intel.com> From: cqiang Message-ID: Date: Wed, 6 Nov 2019 09:01:18 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On 11/5/2019 9:03 PM, Paolo Bonzini wrote: > On 05/11/19 13:51, Xiaoyao Li wrote: >> On 11/5/2019 7:30 PM, Paolo Bonzini wrote: >>> On 05/11/19 10:20, Chenyi Qiang wrote: >>>> The three msr number lists(msrs_to_save[], emulated_msrs[] and >>>> msr_based_features[]) are global arrays of kvm.ko, which are >>>> initialized/adjusted (copy supported MSRs forward to override the >>>> unsupported MSRs) when installing kvm-{intel,amd}.ko, but it doesn't >>>> reset these three arrays to their initial value when uninstalling >>>> kvm-{intel,amd}.ko. Thus, at the next installation, kvm-{intel,amd}.ko >>>> will initialize the modified arrays with some MSRs lost and some MSRs >>>> duplicated. >>>> >>>> So allocate and initialize these three MSR number lists dynamically when >>>> installing kvm-{intel,amd}.ko and free them when uninstalling. >>>> >>>> Cc: stable@vger.kernel.org >>>> Reviewed-by: Xiaoyao Li >>>> Signed-off-by: Chenyi Qiang >>>> --- >>>>   arch/x86/kvm/x86.c | 86 ++++++++++++++++++++++++++++++---------------- >>>>   1 file changed, 57 insertions(+), 29 deletions(-) >>>> >>>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >>>> index ff395f812719..08efcf6351cc 100644 >>>> --- a/arch/x86/kvm/x86.c >>>> +++ b/arch/x86/kvm/x86.c >>>> @@ -1132,13 +1132,15 @@ EXPORT_SYMBOL_GPL(kvm_rdpmc); >>>>    * List of msr numbers which we expose to userspace through >>>> KVM_GET_MSRS >>>>    * and KVM_SET_MSRS, and KVM_GET_MSR_INDEX_LIST. >>>>    * >>>> - * This list is modified at module load time to reflect the >>>> + * The three msr number lists(msrs_to_save, emulated_msrs, >>>> msr_based_features) >>>> + * are allocated and initialized at module load time and freed at >>>> unload time. >>>> + * msrs_to_save is selected from the msrs_to_save_all to reflect the >>>>    * capabilities of the host cpu. This capabilities test skips MSRs >>>> that are >>>> - * kvm-specific. Those are put in emulated_msrs; filtering of >>>> emulated_msrs >>>> + * kvm-specific. Those are put in emulated_msrs_all; filtering of >>>> emulated_msrs >>>>    * may depend on host virtualization features rather than host cpu >>>> features. >>>>    */ >>>>   -static u32 msrs_to_save[] = { >>>> +const u32 msrs_to_save_all[] = { >>> >>> This can remain static. >> >> How about static const u32 msrs_to_save_all[] ? >> >> Or you think static is enough? > > "static const" is best indeed (that's what I meant, but I wasn't very > clear). > Yes, considering the read-only property and scope of these arrays, "static const" is more accurate. Thanks. > Paolo > >>>>       MSR_IA32_SYSENTER_CS, MSR_IA32_SYSENTER_ESP, >>>> MSR_IA32_SYSENTER_EIP, >>>>       MSR_STAR, >>>>   #ifdef CONFIG_X86_64 >>>> @@ -1179,9 +1181,10 @@ static u32 msrs_to_save[] = { >>>>       MSR_ARCH_PERFMON_EVENTSEL0 + 16, MSR_ARCH_PERFMON_EVENTSEL0 + 17, >>>>   }; >>>>   +static u32 *msrs_to_save; >>> >>> You can use ARRAY_SIZE to allocate the destination arrays statically. >> >> It's much better, then we don't need to allocation and free. >> Got it. Thanks! >>> Paolo >>> >