Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030668Ab2ERC1l (ORCPT ); Thu, 17 May 2012 22:27:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:10855 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966624Ab2ERC1i (ORCPT ); Thu, 17 May 2012 22:27:38 -0400 Date: Thu, 17 May 2012 23:22:41 -0300 From: Marcelo Tosatti To: Xudong Hao Cc: avi@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, haitao.shan@intel.com, xiantao.zhang@intel.com, xudong.hao@intel.com Subject: Re: [PATCH 4/4] Enabling Access bit when doing memory swapping Message-ID: <20120518022241.GA14096@amt.cnet> References: <20120516011230.GE14256@hp-xd.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120516011230.GE14256@hp-xd.sh.intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1869 Lines: 45 On Wed, May 16, 2012 at 09:12:30AM +0800, Xudong Hao wrote: > Enabling Access bit when doing memory swapping. > > Signed-off-by: Haitao Shan > Signed-off-by: Xudong Hao > --- > arch/x86/kvm/mmu.c | 13 +++++++------ > arch/x86/kvm/vmx.c | 6 ++++-- > 2 files changed, 11 insertions(+), 8 deletions(-) > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index ff053ca..5f55f98 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -1166,7 +1166,8 @@ static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp, > int young = 0; > > /* > - * Emulate the accessed bit for EPT, by checking if this page has > + * In case of absence of EPT Access and Dirty Bits supports, > + * emulate the accessed bit for EPT, by checking if this page has > * an EPT mapping, and clearing it if it does. On the next access, > * a new EPT mapping will be established. > * This has some overhead, but not as much as the cost of swapping > @@ -1179,11 +1180,11 @@ static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp, > while (spte) { > int _young; > u64 _spte = *spte; > - BUG_ON(!(_spte & PT_PRESENT_MASK)); > - _young = _spte & PT_ACCESSED_MASK; > + BUG_ON(!is_shadow_present_pte(_spte)); > + _young = _spte & shadow_accessed_mask; > if (_young) { > young = 1; > - clear_bit(PT_ACCESSED_SHIFT, (unsigned long *)spte); > + *spte &= ~shadow_accessed_mask; > } Now a dirty bit can be lost. Is there a reason to remove the clear_bit? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/