From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 10/11] KVM: MMU: fix detecting misaligned accessed Date: Wed, 27 Jul 2011 12:15:29 +0300 Message-ID: <4E2FD731.7010206@redhat.com> References: <4E2EA3DB.7040403@cn.fujitsu.com> <4E2EA5AA.2010708@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , LKML , KVM To: Xiao Guangrong Return-path: In-Reply-To: <4E2EA5AA.2010708@cn.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.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