From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752493AbaHRKZM (ORCPT ); Mon, 18 Aug 2014 06:25:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:65152 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750807AbaHRKZJ (ORCPT ); Mon, 18 Aug 2014 06:25:09 -0400 Message-ID: <53F1D476.1030801@redhat.com> Date: Mon, 18 Aug 2014 12:24:54 +0200 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.7.0 MIME-Version: 1.0 To: Wanpeng Li CC: Gleb Natapov , hpa@zytor.com, x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/5] KVM: vmx: don't vmx_segment_cache_clear twice in enter_pmode References: <1408355431-115633-1-git-send-email-wanpeng.li@linux.intel.com> <1408355431-115633-3-git-send-email-wanpeng.li@linux.intel.com> In-Reply-To: <1408355431-115633-3-git-send-email-wanpeng.li@linux.intel.com> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Il 18/08/2014 11:50, Wanpeng Li ha scritto: > vmx_segment_cache_clear() will be called by vmx_set_segment() > which lead to vmx_segment_cache_clear() is called twice in > enter_pmode(). This patch remove the duplicate call site. > > Reviewed-by: Yang Zhang > Signed-off-by: Wanpeng Li > --- > arch/x86/kvm/vmx.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 2963303..c97c44c 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -3183,8 +3183,6 @@ static void enter_pmode(struct kvm_vcpu *vcpu) > > vmx->rmode.vm86_active = 0; > > - vmx_segment_cache_clear(vmx); > - > vmx_set_segment(vcpu, &vmx->rmode.segs[VCPU_SREG_TR], VCPU_SREG_TR); > > flags = vmcs_readl(GUEST_RFLAGS); > I think this is not useful and obscures the code a bit. It would be a bigger improvement to see when fix_pmode_seg really needs to call vmx_set_segment, and avoid the call. Are you seeing enter_pmode high in any profiles? Paolo