linux-kernel - Re: [PATCH 0/3] arm64:msr: Add MSR driver

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Date:   Tue, 1 Dec 2020 22:33:42 +0800
From:   wangrongwei <rongwei.wang@...ux.alibaba.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     catalin.marinas@....com, Will Deacon <will@...nel.org>,
        bjorn.andersson@...aro.org, shawnguo@...nel.org, vkoul@...nel.org,
        geert+renesas@...der.be, Anson.Huang@....com, michael@...le.cc,
        krzk@...nel.org, olof@...om.net, vincenzo.frascino@....com,
        ardb@...nel.org, masahiroy@...nel.org, gshan@...hat.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/3] arm64:msr: Add MSR driver



> 2020年12月1日 下午7:26，Borislav Petkov <bp@...en8.de> 写道：
> 
> On Tue, Dec 01, 2020 at 11:44:52AM +0800, wangrongwei wrote:
>> Indeed, I have read the commit message, and it seems that writes data
>> to a system register may cause many problems. Actually, we have taken
>> this into account. In the current version, we have separated the read
>> and write functions to the system registers into two commands,
> 
> There's rdmsr and wrmsr in msr-tools on x86 too.
Yes, and x86 also provides two instructions with the same name in the instruction set, but not in ARM.
> 
>> In providing the WRASR function, we consider that users should bear
>> the consequences of rewriting registers during the debugging phase. In
>> fact, most of the time we rarely use WRASR, and only use it when we
>> are very confident.
> 
> As I said, there should never never ever be a tool which allows writing
> of registers from userspace. If I could go back in time, I'd stop this
> on x86 but it is too late now. Not for ARM though.
> 
> Also, do you see how all the people who replied to your mail, put the
> text under the quoted text. Do that too, pls, from now on, and refrain
> from top-posting.
Thank you for the reminder, it has been corrected!
> 
> Thx.
> 
> -- 
> Regards/Gruss,
>    Boris.
> 
> https://people.kernel.org/tglx/notes-about-netiquette
Thanks,
Rongwei Wang.