linux-kernel - Re: [PATCH] x86/pkeys: Manually set X86_FEATURE

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Message-ID: <20200227180100.GB18629@zn.tnic>
Date:   Thu, 27 Feb 2020 19:01:00 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Jacob Keller <jacob.e.keller@...el.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
        Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH] x86/pkeys: Manually set X86_FEATURE_OSPKE to preserve
 existing changes

On Wed, Feb 26, 2020 at 04:16:13PM -0800, Jacob Keller wrote:
> I tested this and it resolves my report! Thanks for a timely fix.

Adding your Tested-by.

> I agree with the analysis. Perhaps it would make sense in the long term
> to find a solution where get_cpu_cap can remember what was cleared for
> each CPU and restore those? It already does this using the global
> variables...

get_cpu_cap() remembers if you use setup_force_cpu_cap() but I agree
that that whole feature bit handling is a bit, hm, "strange". It had its
raisins.

FWIW, we had started cleaning those up but then the security nightmares
happened so on the backburner it went...

Thx.

-- 
Regards/Gruss,
    Boris.

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