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

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Message-ID: <b7d8388d-d9df-9cc4-3d07-82e7f807017a@arm.com>
Date:   Wed, 6 Sep 2017 13:30:43 +0100
From:   Vladimir Murzin <vladimir.murzin@....com>
To:     gengdongjiu <gengdongjiu@...wei.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 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
>>
>> .
>>
> 
>