All of lore.kernel.org
 help / color / mirror / Atom feed
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

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
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

_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

  parent reply	other threads:[~2021-05-18 11:51 UTC|newest]

Thread overview: 34+ 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 ` Marc Zyngier
2021-04-29 13:35 ` [PATCH 1/2] firmware/efi: Tell memblock about EFI reservations Marc Zyngier
2021-04-29 13:35   ` Marc Zyngier
2021-05-03 18:56   ` Moritz Fischer
2021-05-03 18:56     ` Moritz Fischer
2021-05-13  3:20     ` Dave Young
2021-05-13  3:20       ` Dave Young
2021-05-13 11:11       ` Marc Zyngier
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
2021-04-29 13:35   ` Marc Zyngier
2021-05-03 18:57   ` Moritz Fischer
2021-05-03 18:57     ` Moritz Fischer
2021-05-12 18:04 ` [PATCH 0/2] arm64: kexec_file_load vs memory reservations Marc Zyngier
2021-05-12 18:04   ` Marc Zyngier
2021-05-13  3:17   ` Dave Young
2021-05-13  3:17     ` Dave Young
2021-05-13 11:07     ` Marc Zyngier
2021-05-13 11:07       ` Marc Zyngier
2021-05-18 11:48 ` Will Deacon [this message]
2021-05-18 11:48   ` Will Deacon
2021-05-18 14:23   ` Bhupesh Sharma
2021-05-18 14:23     ` Bhupesh Sharma
2021-05-19 15:19 ` Catalin Marinas
2021-05-19 15:19   ` Catalin Marinas
2021-05-25 16:22   ` Marc Zyngier
2021-05-25 16:22     ` Marc Zyngier
2021-06-02 14:22 ` James Morse
2021-06-02 14:22   ` James Morse
2021-06-02 15:59   ` Marc Zyngier
2021-06-02 15:59     ` Marc Zyngier
2021-06-02 16:58     ` James Morse
2021-06-02 16:58       ` James Morse

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210518114857.GA7914@willie-the-truck \
    --to=will@kernel.org \
    --cc=ardb@kernel.org \
    --cc=bhupesh.sharma@linaro.org \
    --cc=catalin.marinas@arm.com \
    --cc=ebiederm@xmission.com \
    --cc=guohanjun@huawei.com \
    --cc=james.morse@arm.com \
    --cc=kernel-team@android.com \
    --cc=kexec@lists.infradead.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=lorenzo.pieralisi@arm.com \
    --cc=mark.rutland@arm.com \
    --cc=maz@kernel.org \
    --cc=sudeep.holla@arm.com \
    --cc=takahiro.akashi@linaro.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.