Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753459AbdIFMP3 (ORCPT ); Wed, 6 Sep 2017 08:15:29 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:5565 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752788AbdIFMP0 (ORCPT ); Wed, 6 Sep 2017 08:15:26 -0400 Subject: Re: [PATCH] arm64: KVM: VHE: save and restore some PSTATE bits To: Vladimir Murzin , Marc Zyngier , "christoffer.dall@linaro.org" , "pbonzini@redhat.com" , "rkrcmar@redhat.com" , "linux-arm-kernel@lists.infradead.org" , "kvmarm@lists.cs.columbia.edu" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "suzuki.poulose@arm.com" , , References: <0184EA26B2509940AA629AE1405DD7F2015DF717@DGGEMA503-MBX.china.huawei.com> <2a5d4299-2523-aef5-7db1-f351ca66b562@arm.com> <981d7334-8841-d3e3-0833-1aa061bf97a2@arm.com> <62860a85-c29c-87bb-24b7-c6e5ac6065f9@huawei.com> <31b18967-c32a-1761-7e60-15c0de28203c@arm.com> CC: James Morse , , Huangshaoyu From: gengdongjiu Message-ID: <57ba125f-9c3c-3504-35a6-9800a47450cf@huawei.com> Date: Wed, 6 Sep 2017 20:14:20 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <31b18967-c32a-1761-7e60-15c0de28203c@arm.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.142.68.147] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020201.59AFE6B3.006B,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 570afe614323726a0ec56b533c2c6037 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 955 Lines: 27 On 2017/9/6 20:00, Vladimir Murzin wrote: > On 06/09/17 11:35, gengdongjiu wrote: >> Vladimir, >> >> On 2017/9/6 17:41, Vladimir Murzin wrote: >>> Can you please elaborate on cases where PAN is not enabled? >> >> I mean the informal private usage, For example, he disabled the PAN dynamically to let kernel space to access the user space. >> After he dynamic disabled the PAN, then switched to guest OS. after return to host. he found the PAN stage is modified. >> Of cause this is not a formal usage, in our host kernel, it is always enabled, no dynamic change, but I means it may exist such cases. >> >> > > So, in short, there is no real issue with PAN, right? What about UAO? For the PAN, if host OS dynamically enable/disable PAN should have issue. Do you think that is not a issue as above description? "host OS dynamically disable the PAN, but after go back from the guest OS, The PAN is unexpectedly enabled" > > Cheers > Vladimir > > . >