From: Matt Fleming <matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
To: Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Cc: "Nicolai Stange"
<nicstange-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
"Ingo Molnar" <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
"Thomas Gleixner" <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>,
"H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>,
"x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org"
<x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
"Mika Penttilä"
<mika.penttila-MRsr7dthA9VWk0Htik3J/w@public.gmane.org>,
"Dan Williams"
<dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
"Dave Young" <dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
"linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH v3 2/2] efi: efi_mem_reserve(): don't reserve through memblock after mm_init()
Date: Mon, 9 Jan 2017 13:00:33 +0000 [thread overview]
Message-ID: <20170109130033.GH16838@codeblueprint.co.uk> (raw)
In-Reply-To: <CAKv+Gu9B_amUwKuQCfMj6d96EpcLdeBDm732E0iqKSkRp11Z4w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
On Fri, 06 Jan, at 07:28:40PM, Ard Biesheuvel wrote:
>
> This is my point exactly. But it appears efi_free_boot_services()
> occurs much later than I thought, and so there is a sizabe time window
> where SLAB is up but reservations can still be made. But we don't
> check whether efi_free_boot_services() has been called.
True. This has only been correct thus far because all code has been
audited, but adding a check to catch future offenders is a good idea.
> Another problem is that we never check that the reservation is
> covered by a BootServicesData region, which are the only ones that
> are guaranteed to be retained up to this point.
The runtime regions are guaranteed to be retained too.
Again, this shouldn't actually be a problem today, but the potential
for breakage here warrants some kind of check and loud warning.
WARNING: multiple messages have this Message-ID (diff)
From: Matt Fleming <matt@codeblueprint.co.uk>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: "Nicolai Stange" <nicstange@gmail.com>,
"Ingo Molnar" <mingo@kernel.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
"x86@kernel.org" <x86@kernel.org>,
"Mika Penttilä" <mika.penttila@nextfour.com>,
"Dan Williams" <dan.j.williams@intel.com>,
"Dave Young" <dyoung@redhat.com>,
"linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 2/2] efi: efi_mem_reserve(): don't reserve through memblock after mm_init()
Date: Mon, 9 Jan 2017 13:00:33 +0000 [thread overview]
Message-ID: <20170109130033.GH16838@codeblueprint.co.uk> (raw)
In-Reply-To: <CAKv+Gu9B_amUwKuQCfMj6d96EpcLdeBDm732E0iqKSkRp11Z4w@mail.gmail.com>
On Fri, 06 Jan, at 07:28:40PM, Ard Biesheuvel wrote:
>
> This is my point exactly. But it appears efi_free_boot_services()
> occurs much later than I thought, and so there is a sizabe time window
> where SLAB is up but reservations can still be made. But we don't
> check whether efi_free_boot_services() has been called.
True. This has only been correct thus far because all code has been
audited, but adding a check to catch future offenders is a good idea.
> Another problem is that we never check that the reservation is
> covered by a BootServicesData region, which are the only ones that
> are guaranteed to be retained up to this point.
The runtime regions are guaranteed to be retained too.
Again, this shouldn't actually be a problem today, but the potential
for breakage here warrants some kind of check and loud warning.
next prev parent reply other threads:[~2017-01-09 13:00 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-05 12:51 [PATCH v3 1/2] x86/efi: don't allocate memmap through memblock after mm_init() Nicolai Stange
2017-01-05 12:51 ` Nicolai Stange
[not found] ` <20170105125130.2815-1-nicstange-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-01-05 12:51 ` [PATCH v3 2/2] efi: efi_mem_reserve(): don't reserve " Nicolai Stange
2017-01-05 12:51 ` Nicolai Stange
[not found] ` <20170105125130.2815-2-nicstange-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-01-06 8:35 ` Ard Biesheuvel
2017-01-06 8:35 ` Ard Biesheuvel
2017-01-06 13:02 ` Nicolai Stange
[not found] ` <87wpe8mjdk.fsf-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-01-06 16:41 ` Ard Biesheuvel
2017-01-06 16:41 ` Ard Biesheuvel
[not found] ` <CAKv+Gu_BnSf_LMsWHTeFaTak8iV1Cwex7WBEsufwYRrBzY8KzQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-01-06 17:46 ` Nicolai Stange
2017-01-06 17:46 ` Nicolai Stange
[not found] ` <87showm682.fsf-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-01-06 19:28 ` Ard Biesheuvel
2017-01-06 19:28 ` Ard Biesheuvel
[not found] ` <CAKv+Gu9B_amUwKuQCfMj6d96EpcLdeBDm732E0iqKSkRp11Z4w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-01-08 0:24 ` Nicolai Stange
2017-01-08 0:24 ` Nicolai Stange
2017-01-09 13:07 ` Matt Fleming
2017-01-09 13:00 ` Matt Fleming [this message]
2017-01-09 13:00 ` Matt Fleming
2017-01-05 21:30 ` [PATCH v3 1/2] x86/efi: don't allocate memmap " Dan Williams
2017-01-05 21:30 ` Dan Williams
2017-01-09 6:43 ` [tip:efi/urgent] x86/efi: Don't " tip-bot for Nicolai Stange
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