linux-kernel - Re: x86/paravirt: Use a single ops structure

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Message-ID: <CAB9dFdtw1_YuBXUY3Rb74WisR1iipZK+Sm60pD4cvcrYvbZb6w@mail.gmail.com>
Date:   Tue, 30 Oct 2018 10:33:38 -0300
From:   Marc Dionne <marc.dionne@...istor.com>
To:     jgross@...e.com
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: x86/paravirt: Use a single ops structure

On Mon, Oct 29, 2018 at 11:25 AM Juergen Gross <jgross@...e.com> wrote:
>
> On 29/10/2018 13:58, Marc Dionne wrote:
> > On Tue, Oct 23, 2018 at 2:37 PM Linux Kernel Mailing List
> > <linux-kernel@...r.kernel.org> wrote:
> >>
> >> Commit:     5c83511bdb9832c86be20fb86b783356e2f58062
> >> Parent:     27876f3882fdd4acb3d3614a0133ecdc777fc292
> >> Refname:    refs/heads/master
> >> Web:        https://git.kernel.org/torvalds/c/5c83511bdb9832c86be20fb86b783356e2f58062
> >> Author:     Juergen Gross <jgross@...e.com>
> >> AuthorDate: Tue Aug 28 09:40:19 2018 +0200
> >> Committer:  Thomas Gleixner <tglx@...utronix.de>
> >> CommitDate: Mon Sep 3 16:50:35 2018 +0200
> >>
> >>     x86/paravirt: Use a single ops structure
> >>
> >>     Instead of using six globally visible paravirt ops structures combine
> >>     them in a single structure, keeping the original structures as
> >>     sub-structures.
> >>
> >>     This avoids the need to assemble struct paravirt_patch_template at
> >>     runtime on the stack each time apply_paravirt() is being called (i.e.
> >>     when loading a module).
> >
> > The above commit replaces pv_lock_ops, which was EXPORT_SYMBOL, with
> > something that is part of pv_ops, which is EXPORT_SYMBOL_GPL.    When
> > CONFIG_PARAVIRT_SPINLOCKS is set, this has the side effect of making
> > spin_lock() unusable by out of tree modules, which will likely be an
> > issue for many, if not most of them.
>
> Thanks for noticing!
>
> Sending a patch soon...
>
>
> Juergen

Thanks for the quick patch.  Does this also need fixing for arm/arm64?
I can't easily verify but it seems like it would have the same issue.

Marc