From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754276Ab1G0JPg (ORCPT ); Wed, 27 Jul 2011 05:15:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57460 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753985Ab1G0JPe (ORCPT ); Wed, 27 Jul 2011 05:15:34 -0400 Message-ID: <4E2FD731.7010206@redhat.com> Date: Wed, 27 Jul 2011 12:15:29 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.18) Gecko/20110621 Fedora/3.1.11-1.fc15 Thunderbird/3.1.11 MIME-Version: 1.0 To: Xiao Guangrong CC: Marcelo Tosatti , LKML , KVM Subject: Re: [PATCH 10/11] KVM: MMU: fix detecting misaligned accessed References: <4E2EA3DB.7040403@cn.fujitsu.com> <4E2EA5AA.2010708@cn.fujitsu.com> In-Reply-To: <4E2EA5AA.2010708@cn.fujitsu.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/26/2011 02:31 PM, Xiao Guangrong wrote: > Sometimes, we only modify the last one byte of a pte to update status bit, > for example, clear_bit is used to clear r/w bit in linux kernel and 'andb' > instruction is used in this function, in this case, kvm_mmu_pte_write will > treat it as misaligned access, and the shadow page table is zapped > > @@ -3597,6 +3597,14 @@ static bool detect_write_misaligned(struct kvm_mmu_page *sp, gpa_t gpa, > > offset = offset_in_page(gpa); > pte_size = sp->role.cr4_pae ? 8 : 4; > + > + /* > + * Sometimes, the OS only writes the last one bytes to update status > + * bits, for example, in linux, andb instruction is used in clear_bit(). > + */ > + if (sp->role.level == 1&& !(offset& (pte_size - 1))&& bytes == 1) > + return false; > + Could be true for level > 1, no? -- error compiling committee.c: too many arguments to function