From: Will Deacon <will@kernel.org>
To: Marc Zyngier <maz@kernel.org>
Cc: kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org,
Catalin Marinas <catalin.marinas@arm.com>,
Ard Biesheuvel <ardb@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
James Morse <james.morse@arm.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Hanjun Guo <guohanjun@huawei.com>,
Sudeep Holla <sudeep.holla@arm.com>,
Eric Biederman <ebiederm@xmission.com>,
bhupesh.sharma@linaro.org,
AKASHI Takahiro <takahiro.akashi@linaro.org>,
kernel-team@android.com
Subject: Re: [PATCH 0/2] arm64: kexec_file_load vs memory reservations
Date: Tue, 18 May 2021 12:48:58 +0100 [thread overview]
Message-ID: <20210518114857.GA7914@willie-the-truck> (raw)
In-Reply-To: <20210429133533.1750721-1-maz@kernel.org>
[Fixing Bhupesh's email address]
On Thu, Apr 29, 2021 at 02:35:31PM +0100, Marc Zyngier wrote:
> It recently became apparent that using kexec with kexec_file_load() on
> arm64 is pretty similar to playing Russian roulette.
>
> Depending on the amount of memory, the HW supported and the firmware
> interface used, your secondary kernel may overwrite critical memory
> regions without which the secondary kernel cannot boot (the GICv3 LPI
> tables being a prime example of such reserved regions).
>
> It turns out that there is at least two ways for reserved memory
> regions to be described to kexec: /proc/iomem for the userspace
> implementation, and memblock.reserved for kexec_file. And of course,
> our LPI tables are only reserved using the resource tree, leading to
> the aforementioned stamping. Similar things could happen with ACPI
> tables as well.
>
> On my 24xA53 system artificially limited to 256MB of RAM (yes, it
> boots with that little memory), trying to kexec a secondary kernel
> failed every times. I can only presume that this was mostly tested
> using kdump, which preserves the entire kernel memory range.
>
> This small series aims at triggering a discussion on what are the
> expectations for kexec_file, and whether we should unify the two
> reservation mechanisms.
Bhupesh, since you've been involved with kexec file on arm64 before, please
could you take a look at these patches?
Thanks,
Will
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next prev parent reply other threads:[~2021-05-18 11:51 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-29 13:35 [PATCH 0/2] arm64: kexec_file_load vs memory reservations Marc Zyngier
2021-04-29 13:35 ` [PATCH 1/2] firmware/efi: Tell memblock about EFI reservations Marc Zyngier
2021-05-03 18:56 ` Moritz Fischer
2021-05-13 3:20 ` Dave Young
2021-05-13 11:11 ` Marc Zyngier
2021-04-29 13:35 ` [PATCH 2/2] ACPI: arm64: Reserve the ACPI tables in memblock Marc Zyngier
2021-05-03 18:57 ` Moritz Fischer
2021-05-12 18:04 ` [PATCH 0/2] arm64: kexec_file_load vs memory reservations Marc Zyngier
2021-05-13 3:17 ` Dave Young
2021-05-13 11:07 ` Marc Zyngier
2021-05-18 11:48 ` Will Deacon [this message]
2021-05-18 14:23 ` Bhupesh Sharma
2021-05-19 15:19 ` Catalin Marinas
2021-05-25 16:22 ` Marc Zyngier
2021-06-02 14:22 ` James Morse
2021-06-02 15:59 ` Marc Zyngier
2021-06-02 16:58 ` James Morse
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