linux-kernel - Re: [PATCH v5 1/7] mce: fix set_mce_nospec to always unmap the whole page

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Date:   Sun, 6 Feb 2022 08:30:24 +0000
From:   Jane Chu <jane.chu@...cle.com>
To:     Dan Williams <dan.j.williams@...el.com>,
        Christoph Hellwig <hch@...radead.org>
CC:     "david@...morbit.com" <david@...morbit.com>,
        "djwong@...nel.org" <djwong@...nel.org>,
        "vishal.l.verma@...el.com" <vishal.l.verma@...el.com>,
        "dave.jiang@...el.com" <dave.jiang@...el.com>,
        "agk@...hat.com" <agk@...hat.com>,
        "snitzer@...hat.com" <snitzer@...hat.com>,
        "dm-devel@...hat.com" <dm-devel@...hat.com>,
        "ira.weiny@...el.com" <ira.weiny@...el.com>,
        "willy@...radead.org" <willy@...radead.org>,
        "vgoyal@...hat.com" <vgoyal@...hat.com>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "nvdimm@...ts.linux.dev" <nvdimm@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-xfs@...r.kernel.org" <linux-xfs@...r.kernel.org>
Subject: Re: [PATCH v5 1/7] mce: fix set_mce_nospec to always unmap the whole
 page

On 2/3/2022 9:23 PM, Dan Williams wrote:
> On Thu, Feb 3, 2022 at 5:42 AM Christoph Hellwig <hch@...radead.org> wrote:
>>
>> On Wed, Feb 02, 2022 at 11:07:37PM +0000, Jane Chu wrote:
>>> On 2/2/2022 1:20 PM, Jane Chu wrote:
>>>>> Wouldn't it make more sense to move these helpers out of line rather
>>>>> than exporting _set_memory_present?
>>>>
>>>> Do you mean to move
>>>>      return change_page_attr_set(&addr, numpages, __pgprot(_PAGE_PRESENT), 0);
>>>> into clear_mce_nospec() for the x86 arch and get rid of _set_memory_present?
>>>> If so, sure I'll do that.
>>>
>>> Looks like I can't do that.  It's either exporting
>>> _set_memory_present(), or exporting change_page_attr_set().  Perhaps the
>>> former is more conventional?
>>
>> These helpers above means set_mce_nospec and clear_mce_nospec.  If they
>> are moved to normal functions instead of inlines, there is no need to
>> export the internals at all.
> 
> Agree, {set,clear}_mce_nospec() can just move to arch/x86/mm/pat/set_memory.c.

Got it, will do.

thanks!
-jane