linux-kernel - Re: [PATCH 1/4] efi/x86: make efi_memmap_reserve only insert into boot mem areas

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Message-ID: <CAKv+Gu8oos1Ksp4fMXXn5ug4Gc-GS9KkbQNZb3A7__6wg5X5AQ@mail.gmail.com>
Date:   Fri, 27 Jan 2017 17:04:50 +0000
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     Matt Fleming <matt@...eblueprint.co.uk>
Cc:     Dave Young <dyoung@...hat.com>,
        Nicolai Stange <nicstange@...il.com>,
        "linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "hpa@...or.com" <hpa@...or.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Mika Penttilä <mika.penttila@...tfour.com>,
        Bhupesh Sharma <bhsharma@...hat.com>
Subject: Re: [PATCH 1/4] efi/x86: make efi_memmap_reserve only insert into
 boot mem areas

On 27 January 2017 at 14:48, Matt Fleming <matt@...eblueprint.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?