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Subject: Re: [PATCH 25/43] x86/mm/kaiser: Unmap kernel from userspace page
 tables (core patch)
To: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>
References: <20171124091448.7649-1-mingo@kernel.org>
 <20171124091448.7649-26-mingo@kernel.org>
 <20171124121638.ej2flgfvctw2cqer@hirez.programming.kicks-ass.net>
Cc: linux-kernel@vger.kernel.org, Andy Lutomirski <luto@amacapital.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        "H . Peter Anvin" <hpa@zytor.com>, Borislav Petkov <bp@alien8.de>,
        Linus Torvalds <torvalds@linux-foundation.org>
From: Dave Hansen <dave.hansen@linux.intel.com>
Message-ID: <36922832-274f-89fa-d39d-b73e75292216@linux.intel.com>
Date: Fri, 24 Nov 2017 08:33:09 -0800
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On 11/24/2017 04:16 AM, Peter Zijlstra wrote:
> On Fri, Nov 24, 2017 at 10:14:30AM +0100, Ingo Molnar wrote:
>> +The minimalistic kernel portion of the user page tables try to
>> +map only what is needed to enter/exit the kernel such as the
>> +entry/exit functions themselves and the interrupt descriptor
>> +table (IDT).  
> 
>                 There are a few unnecessary things that get mapped
>> +such as the first C function when entering an interrupt (see
>> +comments in kaiser.c).
> 
> If I understood Andy's patches correctly, this should no longer be
> required. Is this text still correct?

It is out of date.  We were able to remove the irq handler mappings.