[PATCH] arm64: respect mem= for EFI

[Ard Biesheuvel]

On 5 December 2014 at 19:12, Catalin Marinas <catalin.marinas at arm.com> wrote:
> On Thu, Dec 04, 2014 at 11:22:20AM +0000, Mark Rutland wrote:
>> Hi all,
>>
>> While trying to debug a userspace test failure, I noticed that the mem=
>> option didn't work when booting via EFI due to some unfortunate init
>> ordering.
>>
>> However, with that alone fixed (patch below) things blow up early if a
>> mem= option is passed to the kernel, because of the way we currently map
>> the EFI runtime services.
>>
>> I've given this patch a spin atop of Ard's rework of the runtime
>> services mapping [1], and that's far happier; I can boot to userspace
>> and memory is limited int he way I expect.
>>
>> Assuming people are fine with this, would this make sense to append to
>> the runtime services mapping series?
>>
>> Cheers,
>> Mark.
>>
>> [1] https://git.linaro.org/people/ard.biesheuvel/linux-arm.git/shortlog/refs/heads/efi-for-arm64
>>
>> ---->8----
>> When booting with EFI, we acquire the EFI memory map after parsing the
>> early params. This unfortuantely renders the option useless as we call
>> memblock_enforce_memory_limit (which uses memblock_remove_range behind
>> the scenes) before we've added any memblocks. We end up removing
>> nothing, then adding all of memory later when efi_init calls
>> reserve_regions.
>>
>> Instead, we can log the limit and apply this later when we do the rest
>> of the memblock work in memblock_init, which should work regardless of
>> the presence of EFI. At the same time we may as well move the early
>> parameter into arm64's mm/init.c, close to arm64_memblock_init.
>>
>> Any memory which must be mapped (e.g. for use by EFI runtime services)
>> must be mapped explicitly reather than relying on the linear mapping,
>> which may be truncated as a result of a mem= option passed on the kernel
>> command line.
>>
>> Signed-off-by: Mark Rutland <mark.rutland at arm.com>
>> Cc: Ard Biesheuvel <ard.biesheuvel at linaro.org>
>> Cc: Catalin Marinas <catalin.marinas at arm.com>
>> Cc: Leif Lindholm <leif.lindholm at linaro.org>
>> Cc: Will Deacon <will.deacon at arm.com>
>
> Acked-by: Catalin Marinas <catalin.marinas at arm.com>

This works fine on top of the final version of my UEFI virtmap series.

Acked-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
Tested-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>