From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1751693AbdA0WOc (ORCPT <rfc822;w@1wt.eu>);
        Fri, 27 Jan 2017 17:14:32 -0500
Received: from mail-wm0-f51.google.com ([74.125.82.51]:36625 "EHLO
        mail-wm0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751314AbdA0WOY (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Fri, 27 Jan 2017 17:14:24 -0500
Date: Fri, 27 Jan 2017 22:13:11 +0000
From: Matt Fleming <matt@codeblueprint.co.uk>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Dave Young <dyoung@redhat.com>, Nicolai Stange <nicstange@gmail.com>,
        "linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "x86@kernel.org" <x86@kernel.org>, Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, "hpa@zytor.com" <hpa@zytor.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Mika =?iso-8859-1?Q?Penttil=E4?= <mika.penttila@nextfour.com>,
        Bhupesh Sharma <bhsharma@redhat.com>
Subject: Re: [PATCH 1/4] efi/x86: make efi_memmap_reserve only insert into
 boot mem areas
Message-ID: <20170127221311.GH31613@codeblueprint.co.uk>
References: <20170112094118.815108042@redhat.com>
 <20170112094214.860924858@redhat.com>
 <87r348r0k9.fsf@gmail.com>
 <20170112212952.GB2709@dhcp-128-65.nay.redhat.com>
 <20170127144813.GE31613@codeblueprint.co.uk>
 <CAKv+Gu8oos1Ksp4fMXXn5ug4Gc-GS9KkbQNZb3A7__6wg5X5AQ@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAKv+Gu8oos1Ksp4fMXXn5ug4Gc-GS9KkbQNZb3A7__6wg5X5AQ@mail.gmail.com>
User-Agent: Mutt/1.5.24+41 (02bc14ed1569) (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, 27 Jan, at 05:04:50PM, Ard Biesheuvel wrote:
> On 27 January 2017 at 14:48, Matt Fleming <matt@codeblueprint.co.uk> wrote:
> > On Fri, 13 Jan, at 05:29:52AM, Dave Young wrote:
> >>
> >> It sounds reasonable though I'm still not sure about EFI_LOADER*.
> >>
> >> The main purpose of this patch is to address the invalid mem ranges
> >> case. As Ard mentioned I will test with Peter's patch first, if it works
> >> fine I would like to either drop this patch as a future improvement or add
> >> it at the end of the next post.
> >>
> >> Matt, what's your opinion about the boot_only check and the EFI_LOADERS*
> >> question?
> >
> > The main reason that efi_mem_reserve() isn't used for EFI_LOADER
> > regions today is because we already have a mechanism for reserving it
> > via memblock_reserve(), which we do during a very early stage of boot
> > when parsing all the different types of SETUP_* objects.
> >
> > It's questionable whether it would make sense to switch to
> > efi_mem_reserve() for EFI_LOADER regions because then you'd
> > potentially have different APIs for different SETUP_* objects.
> >
> > As things stand today, I would suggest triggering a WARN_ON() if
> > someone tries to efi_mem_reserve() an EFI_LOADER region, until/unless
> > the day comes when a user exists in the kernel.
> 
> Hmm, I just queued this. Should we drop it again?

Does dropping it break the entire series?

Having had some time to re-read Dave's commit log, it sounds like it
just papers over a bug, which is that efi_memmap_insert() cannot deal
with reserved entries, which all look like they describe the same
region.

So I guess my question is: Shouldn't you fix that instead of requiring
the caller of efi_memmap_insert() to understand what type of entries
it's mapping?