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

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Message-ID: <CAPcyv4g7Vqp6Z2+EXHdv95oqQxfdvPDAnzBiRG2KqobaHzOAsg@mail.gmail.com>
Date:   Thu, 3 Feb 2022 21:23:00 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     Jane Chu <jane.chu@...cle.com>,
        "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 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.