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=unavailable 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 13949ECE58C for ; Wed, 9 Oct 2019 16:38:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DD693206BB for ; Wed, 9 Oct 2019 16:38:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731619AbfJIQig (ORCPT ); Wed, 9 Oct 2019 12:38:36 -0400 Received: from mga06.intel.com ([134.134.136.31]:9175 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730674AbfJIQif (ORCPT ); Wed, 9 Oct 2019 12:38:35 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 09 Oct 2019 09:38:35 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.67,276,1566889200"; d="scan'208";a="205799690" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.41]) by orsmga002.jf.intel.com with ESMTP; 09 Oct 2019 09:38:35 -0700 Date: Wed, 9 Oct 2019 09:38:35 -0700 From: Sean Christopherson To: Paolo Bonzini Cc: Radim =?utf-8?B?S3LEjW3DocWZ?= , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Reto Buerki , Liran Alon Subject: Re: [PATCH v2 4/8] KVM: VMX: Optimize vmx_set_rflags() for unrestricted guest Message-ID: <20191009163835.GB19952@linux.intel.com> References: <20190927214523.3376-1-sean.j.christopherson@intel.com> <20190927214523.3376-5-sean.j.christopherson@intel.com> <99e57095-d855-99d7-e10e-a415c6ef13b2@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <99e57095-d855-99d7-e10e-a415c6ef13b2@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Oct 09, 2019 at 12:40:53PM +0200, Paolo Bonzini wrote: > 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; Works for me. Do you want me to spin a v3 to incorporate this and remove the open coding of the RIP/RSP accessors? Or are you planning on squashing the changes as you apply?