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

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Date:   Mon, 15 Jul 2019 16:52:11 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     Borislav Petkov <bp@...en8.de>,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        Stephane Eranian <eranian@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        FengTang <feng.tang@...el.com>, 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>,
        LKML <linux-kernel@...r.kernel.org>,
        Alok Kataria <akataria@...are.com>,
        Nadav Amit <namit@...are.com>
Subject: Re: [PATCH] x86/paravirt: Drop {read,write}_cr8() hooks

On 15.07.19 16:26, Andy Lutomirski wrote:
> 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.
> 

Okay, in that case I'd suggest to remove "cr8" from struct saved_context
as it won't be used any longer.


Juergen