From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xiao Guangrong Subject: Re: [PATCH 1/2] KVM: MMU: don't make direct sp read-only if !map_writable Date: Tue, 14 Dec 2010 09:53:29 +0800 Message-ID: <4D06CE19.9000908@cn.fujitsu.com> References: <4D05F5F6.3070909@cn.fujitsu.com> <4D05F62D.9040308@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , LKML , KVM To: Avi Kivity Return-path: In-Reply-To: <4D05F62D.9040308@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 12/13/2010 06:32 PM, Avi Kivity wrote: > On 12/13/2010 12:31 PM, Xiao Guangrong wrote: >> Currently, if the page is not allowed to write, then it can drop >> ACC_WRITE_MASK in pte_access, and the direct sp's access is: >> gw->pt_access& gw->pte_access >> so, it also removes the write access in the direct sp. >> >> There is a problem: if the access of those pages which map thought the >> same >> mapping in guest is different in host, it causes host switch direct sp >> very >> frequently. > > I just sent a patch to fix this in a different way, please review it. > Your patch is good for me, please ignore this one :-) Umm, do we need move "access &= ~ACC_WRITE_MASK" into set_spte() then can remove the same code in the caller?