linux-kernel - Re: [PATCH v23 07/28] x86/mm: Remove _PAGE

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Message-ID: <81fa71ee-3b0b-b959-b8c2-19e1a5adc4c4@intel.com>
Date:   Mon, 22 Mar 2021 07:52:31 -0700
From:   "Yu, Yu-cheng" <yu-cheng.yu@...el.com>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
Cc:     x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-mm@...ck.org,
        linux-arch@...r.kernel.org, linux-api@...r.kernel.org,
        Arnd Bergmann <arnd@...db.de>,
        Andy Lutomirski <luto@...nel.org>,
        Balbir Singh <bsingharora@...il.com>,
        Borislav Petkov <bp@...en8.de>,
        Cyrill Gorcunov <gorcunov@...il.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Eugene Syromiatnikov <esyr@...hat.com>,
        Florian Weimer <fweimer@...hat.com>,
        "H.J. Lu" <hjl.tools@...il.com>, Jann Horn <jannh@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Kees Cook <keescook@...omium.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Nadav Amit <nadav.amit@...il.com>,
        Oleg Nesterov <oleg@...hat.com>, Pavel Machek <pavel@....cz>,
        Peter Zijlstra <peterz@...radead.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@...el.com>,
        Dave Martin <Dave.Martin@....com>,
        Weijiang Yang <weijiang.yang@...el.com>,
        Pengfei Xu <pengfei.xu@...el.com>,
        Haitao Huang <haitao.huang@...el.com>,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH v23 07/28] x86/mm: Remove _PAGE_DIRTY from kernel RO pages

On 3/22/2021 2:13 AM, Kirill A. Shutemov wrote:
> On Tue, Mar 16, 2021 at 08:10:33AM -0700, Yu-cheng Yu wrote:
>> The x86 family of processors do not directly create read-only and Dirty
>> PTEs.  These PTEs are created by software.  One such case is that kernel
>> read-only pages are historically setup as Dirty.
>>
>> New processors that support Shadow Stack regard read-only and Dirty PTEs as
>> shadow stack pages.  This results in ambiguity between shadow stack and
>> kernel read-only pages.  To resolve this, removed Dirty from kernel read-
>> only pages.
>>
>> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@...el.com>
>> Cc: "H. Peter Anvin" <hpa@...or.com>
>> Cc: Kees Cook <keescook@...omium.org>
>> Cc: Thomas Gleixner <tglx@...utronix.de>
>> Cc: Dave Hansen <dave.hansen@...ux.intel.com>
>> Cc: Christoph Hellwig <hch@....de>
>> Cc: Andy Lutomirski <luto@...nel.org>
>> Cc: Ingo Molnar <mingo@...hat.com>
>> Cc: Borislav Petkov <bp@...en8.de>
>> Cc: Peter Zijlstra <peterz@...radead.org>
> 
> Looks good to me.
> 
> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> 

Thanks for reviewing.

Yu-cheng