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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 5B4D3ECE58D for ; Wed, 9 Oct 2019 10:40:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3CDE32133F for ; Wed, 9 Oct 2019 10:40:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730708AbfJIKk6 (ORCPT ); Wed, 9 Oct 2019 06:40:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47754 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727219AbfJIKk5 (ORCPT ); Wed, 9 Oct 2019 06:40:57 -0400 Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 62CF27EBAE for ; Wed, 9 Oct 2019 10:40:57 +0000 (UTC) Received: by mail-wr1-f72.google.com with SMTP id k4so925872wru.1 for ; Wed, 09 Oct 2019 03:40:57 -0700 (PDT) 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:openpgp:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=abCd/PKSbtDlFwGQhdNXFUNQ7UiKs2xVKNU/aJBjBBk=; b=S4r7PWa3qaidb64I8KqUm7eIFgtTPK1Yg4EEKZADNBq7gasoh19Zapn4+FC3hS+Qcv zv/G/EwnT5kLNuJj8UiQUQlhqQXcOl2A0cOBbakO1lVaNCEzunHl1h+gDT+6w9fX0eWx X4rRvco9ULm9Rjj5yPkYtIKx8cOndmyMr2cRiH04efojcaM/5IEFq5yF451Aka9kPYGv wVyzCnmQRFxX+OWpEmw/rx2Wk+AWWBMR/Y8vFvetqNxJLdHGn23fUuAwCj2PlPfZiDoB GEiVu1Go/iycbWpbTDErXduoY2/6qVqKTIPTvmE78WNdTOGKXmSIG8LhGGwI3kJDuR9a xPxA== X-Gm-Message-State: APjAAAXBliojnOqhgPzVO6S6OnPD/GamU2Ky6VHjoVXZz5xWPKxoY1lm MoMzb/yI8+t18n9Pzp/QU77BoMIrffU6wFOxg+X4L7AmBJvJob9j1Cef8NQIOjM4y51sl9bRhJS gFFOPLf+3JJUGlnyXBKXrj/DS X-Received: by 2002:a1c:2681:: with SMTP id m123mr2216812wmm.92.1570617655928; Wed, 09 Oct 2019 03:40:55 -0700 (PDT) X-Google-Smtp-Source: APXvYqwT2x/b1oBSgwdq+6U7Wh93Jf0B2d8CCa3AaNhng0FeeOSIcddFsBpCniq0qNd7tXS1DtNUgg== X-Received: by 2002:a1c:2681:: with SMTP id m123mr2216782wmm.92.1570617655636; Wed, 09 Oct 2019 03:40:55 -0700 (PDT) Received: from [192.168.10.150] ([93.56.166.5]) by smtp.gmail.com with ESMTPSA id d78sm1880033wmd.47.2019.10.09.03.40.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 09 Oct 2019 03:40:55 -0700 (PDT) Subject: Re: [PATCH v2 4/8] KVM: VMX: Optimize vmx_set_rflags() for unrestricted guest To: Sean Christopherson , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= Cc: Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Reto Buerki , Liran Alon References: <20190927214523.3376-1-sean.j.christopherson@intel.com> <20190927214523.3376-5-sean.j.christopherson@intel.com> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: <99e57095-d855-99d7-e10e-a415c6ef13b2@redhat.com> Date: Wed, 9 Oct 2019 12:40:53 +0200 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: <20190927214523.3376-5-sean.j.christopherson@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27/09/19 23:45, Sean Christopherson wrote: > Rework vmx_set_rflags() to avoid the extra code need to handle emulation > of real mode and invalid state when unrestricted guest is disabled. The > primary reason for doing so is to avoid the call to vmx_get_rflags(), > which will incur a VMREAD when RFLAGS is not already available. When > running nested VMs, the majority of calls to vmx_set_rflags() will occur > without an associated vmx_get_rflags(), i.e. when stuffing GUEST_RFLAGS > during transitions between vmcs01 and vmcs02. > > Note, vmx_get_rflags() guarantees RFLAGS is marked available. Slightly nicer this way: diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 8de9853d7ab6..62ab19d65efd 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1431,9 +1431,17 @@ unsigned long vmx_get_rflags(struct kvm_vcpu *vcpu) void vmx_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags) { struct vcpu_vmx *vmx = to_vmx(vcpu); - unsigned long old_rflags = vmx_get_rflags(vcpu); + unsigned long old_rflags; + + if (enable_unrestricted_guest) { + __set_bit(VCPU_EXREG_RFLAGS, (ulong *)&vcpu->arch.regs_avail); + vmx->rflags = rflags; + vmcs_writel(GUEST_RFLAGS, rflags); + return; + } + + old_rflags = vmx_get_rflags(vcpu); - __set_bit(VCPU_EXREG_RFLAGS, (ulong *)&vcpu->arch.regs_avail); vmx->rflags = rflags; if (vmx->rmode.vm86_active) { vmx->rmode.save_rflags = rflags; Paolo