[PATCH 0/2] arm64: kexec_file_load vs memory reservations

[Bhupesh Sharma]

Hi Will,

On Tue, 18 May 2021 at 17:19, Will Deacon <will at kernel.org> wrote:
>
> [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 for adding me in Cc.
Yes, I will look and test these patches asap.

Regards,
Bhupesh