From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753904Ab2IXLYV (ORCPT ); Mon, 24 Sep 2012 07:24:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36694 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752459Ab2IXLYT (ORCPT ); Mon, 24 Sep 2012 07:24:19 -0400 Date: Mon, 24 Sep 2012 13:24:16 +0200 From: Gleb Natapov To: Xiao Guangrong Cc: Avi Kivity , Marcelo Tosatti , LKML , KVM Subject: Re: [PATCH v3 1/7] KVM: MMU: fix release noslot pfn Message-ID: <20120924112416.GA23096@redhat.com> References: <505C0FA8.5070007@linux.vnet.ibm.com> <505C0FCF.2070308@linux.vnet.ibm.com> <20120923091335.GA20907@redhat.com> <505FE8B4.8030309@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <505FE8B4.8030309@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 24, 2012 at 12:59:32PM +0800, Xiao Guangrong wrote: > On 09/23/2012 05:13 PM, Gleb Natapov wrote: > > On Fri, Sep 21, 2012 at 02:57:19PM +0800, Xiao Guangrong wrote: > >> We can not directly call kvm_release_pfn_clean to release the pfn > >> since we can meet noslot pfn which is used to cache mmio info into > >> spte > >> > > Wouldn't it be better to move the check into kvm_release_pfn_clean()? > > I think there is no reason for us to prefer to adding this branch in > the common code. :) Is the function performance critical? Is function called without the check on a hot path? The function already contains much heavier kvm_is_mmio_pfn() check. If most/all function invocation require check before call it's better to move it inside. -- Gleb.