Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753556AbdIFMau (ORCPT ); Wed, 6 Sep 2017 08:30:50 -0400 Received: from foss.arm.com ([217.140.101.70]:50118 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752766AbdIFMar (ORCPT ); Wed, 6 Sep 2017 08:30:47 -0400 Subject: Re: [PATCH] arm64: KVM: VHE: save and restore some PSTATE bits To: gengdongjiu , 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" , mark.rutland@arm.com, catalin.marinas@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> <57ba125f-9c3c-3504-35a6-9800a47450cf@huawei.com> Cc: James Morse , zhanghaibin7@huawei.com, Huangshaoyu From: Vladimir Murzin Message-ID: Date: Wed, 6 Sep 2017 13:30:43 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <57ba125f-9c3c-3504-35a6-9800a47450cf@huawei.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1101 Lines: 36 On 06/09/17 13:14, gengdongjiu wrote: > > > 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" Do you see effect of "PAN is unexpectedly enabled"? Cheers Vladimir > >> >> Cheers >> Vladimir >> >> . >> > >