Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH] x86/pkeys: Manually set X86_FEATURE_OSPKE to preserve
 existing changes
To:     Borislav Petkov <bp@alien8.de>
Cc:     Sean Christopherson <sean.j.christopherson@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>, linux-kernel@vger.kernel.org,
        Dave Hansen <dave.hansen@linux.intel.com>
References: <20200226231615.13664-1-sean.j.christopherson@intel.com>
 <a492b4f4-4a54-5e5a-b79f-e21f9038f259@intel.com>
 <20200227180100.GB18629@zn.tnic>
From:   Jacob Keller <jacob.e.keller@intel.com>
Organization: Intel Corporation
Message-ID: <fbf2b74e-bc37-985a-11f0-03e5ae5e390c@intel.com>
Date:   Thu, 27 Feb 2020 10:20:36 -0800
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101
 Thunderbird/68.5.0
MIME-Version: 1.0
In-Reply-To: <20200227180100.GB18629@zn.tnic>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


On 2/27/2020 10:01 AM, Borislav Petkov wrote:
> 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.
> 

Yep, thanks.

>> 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.

Right. Nothing quite equivalent to that for per-CPU changes though.

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

Completely understandable. Especially since changes here are tricky to
get right, this being a case in point.

Thanks,
Jake