From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756291Ab3A2C6J (ORCPT ); Mon, 28 Jan 2013 21:58:09 -0500 Received: from e28smtp04.in.ibm.com ([122.248.162.4]:47267 "EHLO e28smtp04.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753008Ab3A2C6I (ORCPT ); Mon, 28 Jan 2013 21:58:08 -0500 Message-ID: <51073AB7.3050207@linux.vnet.ibm.com> Date: Tue, 29 Jan 2013 10:57:59 +0800 From: Xiao Guangrong User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Gleb Natapov CC: Marcelo Tosatti , Avi Kivity , LKML , KVM Subject: Re: [PATCH v2 01/12] KVM: MMU: lazily drop large spte References: <50FFB5A1.5090708@linux.vnet.ibm.com> <20130127120657.GA21650@redhat.com> In-Reply-To: <20130127120657.GA21650@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13012902-5564-0000-0000-00000665EDF4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/27/2013 08:06 PM, Gleb Natapov wrote: > On Wed, Jan 23, 2013 at 06:04:17PM +0800, Xiao Guangrong wrote: >> Do not drop large spte until it can be insteaded by small pages so that >> the guest can happliy read memory through it >> >> The idea is from Avi: >> | As I mentioned before, write-protecting a large spte is a good idea, >> | since it moves some work from protect-time to fault-time, so it reduces >> | jitter. This removes the need for the return value. >> >> Signed-off-by: Xiao Guangrong >> --- >> arch/x86/kvm/mmu.c | 21 ++++++--------------- >> 1 files changed, 6 insertions(+), 15 deletions(-) >> >> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c >> index 9f628f7..0f90269 100644 >> --- a/arch/x86/kvm/mmu.c >> +++ b/arch/x86/kvm/mmu.c >> @@ -1105,7 +1105,7 @@ static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep) >> >> /* >> * Write-protect on the specified @sptep, @pt_protect indicates whether >> - * spte writ-protection is caused by protecting shadow page table. >> + * spte write-protection is caused by protecting shadow page table. >> * @flush indicates whether tlb need be flushed. >> * >> * Note: write protection is difference between drity logging and spte >> @@ -1114,31 +1114,23 @@ static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep) >> * its dirty bitmap is properly set. >> * - for spte protection, the spte can be writable only after unsync-ing >> * shadow page. >> - * >> - * Return true if the spte is dropped. >> */ >> -static bool >> +static void >> spte_write_protect(struct kvm *kvm, u64 *sptep, bool *flush, bool pt_protect) > Since return value is not longer used make the function return true if flush is needed > instead of returning it via pointer to a variable. Right, i forgot to check it, will update it in the next version. Thanks for your pointing it out.