linux-kernel - Re: [PATCH] arm64: KVM: VHE: save and restore some PSTATE bits

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Message-ID: <57ba125f-9c3c-3504-35a6-9800a47450cf@huawei.com>
Date:   Wed, 6 Sep 2017 20:14:20 +0800
From:   gengdongjiu <gengdongjiu@...wei.com>
To:     Vladimir Murzin <vladimir.murzin@....com>,
        Marc Zyngier <marc.zyngier@....com>,
        "christoffer.dall@...aro.org" <christoffer.dall@...aro.org>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "rkrcmar@...hat.com" <rkrcmar@...hat.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "kvmarm@...ts.cs.columbia.edu" <kvmarm@...ts.cs.columbia.edu>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "suzuki.poulose@....com" <suzuki.poulose@....com>,
        <mark.rutland@....com>, <catalin.marinas@....com>
CC:     James Morse <James.Morse@....com>, <zhanghaibin7@...wei.com>,
        Huangshaoyu <huangshaoyu@...wei.com>
Subject: Re: [PATCH] arm64: KVM: VHE: save and restore some PSTATE bits



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
> 
> .
>