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Message-ID: <CAMj1kXFjsdnNy=7yMwCQsAyKrratU0_9eemviHug6VeGbSEmOg@mail.gmail.com>
Date: Mon, 31 May 2021 21:36:34 +0200
From: Ard Biesheuvel <ardb@...nel.org>
To: Marc Zyngier <maz@...nel.org>
Cc: kexec@...ts.infradead.org,
Linux ARM <linux-arm-kernel@...ts.infradead.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Mark Rutland <mark.rutland@....com>,
James Morse <james.morse@....com>,
Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
Hanjun Guo <guohanjun@...wei.com>,
Sudeep Holla <sudeep.holla@....com>,
Eric Biederman <ebiederm@...ssion.com>,
Bhupesh SHARMA <bhupesh.sharma@...aro.org>,
AKASHI Takahiro <takahiro.akashi@...aro.org>,
Dave Young <dyoung@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Moritz Fischer <mdf@...nel.org>,
Android Kernel Team <kernel-team@...roid.com>
Subject: Re: [PATCH v2 0/5] arm64: Make kexec_file_load honor iomem reservations
On Mon, 31 May 2021 at 11:57, Marc Zyngier <maz@...nel.org> wrote:
>
> This series is a complete departure from the approach I initially sent
> almost a month ago[0]. Instead of trying to teach EFI, ACPI and other
> subsystem to use memblock, I've decided to stick with the iomem
> resource tree and use that exclusively for arm64.
>
> This means that my current approach is (despite what I initially
> replied to both Dave and Catalin) to provide an arm64-specific
> implementation of arch_kexec_locate_mem_hole() which walks the
> resource tree and excludes ranges of RAM that have been registered for
> any odd purpose. This is exactly what the userspace implementation
> does, and I don't really see a good reason to diverge from it.
>
> Again, this allows my Synquacer board to reliably use kexec_file_load
> with as little as 256M, something that would always fail before as it
> would overwrite most of the reserved tables.
>
> Although this series still targets 5.14, the initial patch is a
> -stable candidate, and disables non-kdump uses of kexec_file_load. I
> have limited it to 5.10, as earlier kernels will require a different,
> probably more invasive approach.
>
> Catalin, Ard: although this series has changed a bit compared to v1,
> I've kept your AB/RB tags. Should anything seem odd, please let me
> know and I'll drop them.
>
Fine with me.
> Thanks,
>
> M.
>
> * From v1 [1]:
> - Move the overlap exclusion into find_next_iomem_res()
> - Handle child resource not overlapping with parent
> - Provide walk_system_ram_excluding_child_res() as a top level
> walker
> - Simplify arch-specific code
> - Add initial patch disabling non-crash kernels
>
> [0] https://lore.kernel.org/r/20210429133533.1750721-1-maz@kernel.org
> [1] https://lore.kernel.org/r/20210526190531.62751-1-maz@kernel.org
>
> Marc Zyngier (5):
> arm64: kexec_file: Forbid non-crash kernels
> kexec_file: Make locate_mem_hole_callback global
> kernel/resource: Allow find_next_iomem_res() to exclude overlapping
> child resources
> kernel/resource: Introduce walk_system_ram_excluding_child_res()
> arm64: kexec_image: Restore full kexec functionnality
>
> arch/arm64/kernel/kexec_image.c | 39 ++++++++++++++++
> include/linux/ioport.h | 3 ++
> include/linux/kexec.h | 1 +
> kernel/kexec_file.c | 6 +--
> kernel/resource.c | 82 +++++++++++++++++++++++++++++----
> 5 files changed, 119 insertions(+), 12 deletions(-)
>
> --
> 2.30.2
>
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