linux-kernel - Re: [PATCH] x86/paravirt: Drop {read,write}

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Date:   Mon, 15 Jul 2019 07:26:25 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     Juergen Gross <jgross@...e.com>
Cc:     Andrew Cooper <andrew.cooper3@...rix.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Borislav Petkov <bp@...en8.de>,
        Stephane Eranian <eranian@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        FengTang <feng.tang@...el.com>,
        Andy Lutomirski <luto@...nel.org>, X86 ML <x86@...nel.org>,
        Linux Virtualization <virtualization@...ts.linux-foundation.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        "Rafael J.Wysocki" <rjw@...ysocki.net>,
        Pavel Machek <pavel@....cz>,
        Alok Kataria <akataria@...are.com>,
        Nadav Amit <namit@...are.com>
Subject: Re: [PATCH] x86/paravirt: Drop {read,write}_cr8() hooks

On Mon, Jul 15, 2019 at 6:23 AM Juergen Gross <jgross@...e.com> wrote:
>
> On 15.07.19 15:00, Andrew Cooper wrote:
> > There is a lot of infrastructure for functionality which is used
> > exclusively in __{save,restore}_processor_state() on the suspend/resume
> > path.
> >
> > cr8 is an alias of APIC_TASKPRI, and APIC_TASKPRI is saved/restored
> > independently by lapic_{suspend,resume}().
>
> Aren't those called only with CONFIG_PM set?
>


Unless I'm missing something, we only build any of the restore code
(including the write_cr8() call) if CONFIG_PM_SLEEP is set, and that
selects CONFIG_PM, so we should be fine, I think.