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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 CE925C432C0 for ; Wed, 20 Nov 2019 12:21:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A31D822310 for ; Wed, 20 Nov 2019 12:21:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KGETTphF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729133AbfKTMVm (ORCPT ); Wed, 20 Nov 2019 07:21:42 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:31650 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728611AbfKTMVm (ORCPT ); Wed, 20 Nov 2019 07:21:42 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1574252500; h=from:from:reply-to:subject:subject: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=0y+Va4NBLdVxptKCFSjrSqw/jstEexITDbBbQwJO4B4=; b=KGETTphFxIk9KLvcppqsxEH/0BCMm0Fr0n4wkhLgD5G1t8g+Rk3eb9FTd8j7qWc+4cyIQF 5lMNDTThZTnJH5EBLgLuf4prJV4/67kMA2Mfqm6OLe5aRSVi6BZctyNINF+IkFsjo1cfsZ QObUhIEwOwbRaJ18iHi8mLeqfEqgv2s= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-282-ZI7HMh2TPMyq1suL5LJojQ-1; Wed, 20 Nov 2019 07:21:39 -0500 Received: by mail-wr1-f70.google.com with SMTP id w9so21109530wrn.9 for ; Wed, 20 Nov 2019 04:21:38 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=3CRYoC+FXuRRRB1nkQ2UTEB7lD0/kwekRSpLwkYD6lI=; b=ZSIPbCvfzw/My5VkrK5a/9KsPdsyG6jMNVsN2TudRH+DiDw9chkmPKZ1A1A2JIIGqt Umn+mF647mIR9tl2sJ4FJ9DCgqNncpUIqgfkM73iGzBB2wkWGc8wGa5rWRtLrzM/cqaj 3PgXXpd6AVvKgbENWfSOwH1i0oej1NEuGrup60wMS46VUKlveSb1jlYINL8SkN/eNCAm 6Og+e7QmxJIW/oaBYlkLUJpB+wBYuC7cMt+GmTFVH7+DGOfTtSbnpDs38oqbWUg8fQZk EISOFktixPEkSxjLYrA2LoUgZQ4NvLyVn6Sg7pN1yQtDXjmj5YLccM2miQlY6lb/dpVY Eoww== X-Gm-Message-State: APjAAAWLkqm94cp09kGaqOLVMDiZknSMIPf3GLXRDfEGM8D37XmDaz18 RE0q7AHEF8zUOWJbzHp+TEzqySec5bhL7xUixgTc35AzoCZWVAKEGpwVK9qSZRN7sjXId/FAb5A MjqxomsRWlLgGgwGIKqYx2/ci X-Received: by 2002:adf:dc81:: with SMTP id r1mr3153630wrj.84.1574252497878; Wed, 20 Nov 2019 04:21:37 -0800 (PST) X-Google-Smtp-Source: APXvYqyKPOrrwukpzYwVmy5KkrfH43kXkleuhypNH0euma/SjTaLdY4e1rCrLeWxMJWnK4K36Jyv+Q== X-Received: by 2002:adf:dc81:: with SMTP id r1mr3153590wrj.84.1574252497590; Wed, 20 Nov 2019 04:21:37 -0800 (PST) Received: from ?IPv6:2001:b07:6468:f312:dc24:9a59:da87:5724? ([2001:b07:6468:f312:dc24:9a59:da87:5724]) by smtp.gmail.com with ESMTPSA id u16sm31686955wrr.65.2019.11.20.04.21.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 20 Nov 2019 04:21:36 -0800 (PST) Subject: Re: [PATCH 4/5] KVM: vmx: implement MSR_IA32_TSX_CTRL disable RTM functionality To: Jim Mattson Cc: LKML , kvm list , Sean Christopherson References: <1574101067-5638-1-git-send-email-pbonzini@redhat.com> <1574101067-5638-5-git-send-email-pbonzini@redhat.com> From: Paolo Bonzini Message-ID: <656c0af1-6c56-8a08-ff86-745409f6968c@redhat.com> Date: Wed, 20 Nov 2019 13:21:35 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-MC-Unique: ZI7HMh2TPMyq1suL5LJojQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19/11/19 22:06, Jim Mattson wrote: >> + switch (index) { >> + case MSR_IA32_TSX_CTRL: >> + /* No need to pass TSX_CTRL_CPUID_CLEAR through.= */ >> + vmx->guest_msrs[j].mask =3D ~(u64)TSX_CTRL_CPUID= _CLEAR; >> + break; > Why even bother with the special case here? Does this make the wrmsr fast= er? >=20 No, but it can avoid the wrmsr altogether if the guest uses the same DISABLE_RTM setting but a different value for CPUID_CLEAR. More important, while I am confident re-enabling TSX while in the kernel and only restoring MSR_IA32_TSX_CTRL on return to userspace, I'm more wary of changing CPUID bits while the kernel is running. I will update the comment. Paolo