linux-kernel - Re: [Patch v3] x86/head/64: remove redundant check on level2_kernel_pgt's _PAGE

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Message-ID: <wwmqtzeukfrzriysxe3b5ueo5iehqnaf55puaok33cbu56pemb@rzq2m7naja4q>
Date: Thu, 23 May 2024 15:40:57 +0300
From: "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
To: Wei Yang <richard.weiyang@...il.com>
Cc: tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, 
	dave.hansen@...ux.intel.com, x86@...nel.org, linux-kernel@...r.kernel.org, 
	Ingo Molnar <mingo@...nel.org>, Steve Wahl <steve.wahl@....com>
Subject: Re: [Patch v3] x86/head/64: remove redundant check on
 level2_kernel_pgt's _PAGE_PRESENT bit

On Thu, May 23, 2024 at 12:35:39PM +0000, Wei Yang wrote:
> Remove a redundant check on kernel code's PMD _PAGE_PRESENT attribute
> before fix up.
> 
> Current process looks like this:
> 
>     pmd in [0, _text)
>         unset _PAGE_PRESENT
>     pmd in [_text, _end]
>         if (_PAGE_PRESENT)
>             fix up delta
>     pmd in (_end, 512)
>         unset _PAGE_PRESENT
> 
> level2_kernel_pgt compiled with _PAGE_PRESENT set. The check is
> redundant
> 
> Signed-off-by: Wei Yang <richard.weiyang@...il.com>
> CC: Thomas Gleixner <tglx@...utronix.de>
> CC: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> CC: Ingo Molnar <mingo@...nel.org>
> CC: Steve Wahl <steve.wahl@....com>

Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

-- 
  Kiryl Shutsemau / Kirill A. Shutemov