Re: [PATCH AUTOSEL 4.19 133/191] efi: honour memory reservations passed via a linux specific config table

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On Sun, Nov 10, 2019 at 08:33:47AM +0100, Ard Biesheuvel wrote:
On Sun, 10 Nov 2019 at 03:44, Sasha Levin <sashal@xxxxxxxxxx> wrote:

From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>

[ Upstream commit 71e0940d52e107748b270213a01d3b1546657d74 ]

In order to allow the OS to reserve memory persistently across a
kexec, introduce a Linux-specific UEFI configuration table that
points to the head of a linked list in memory, allowing each kernel
to add list items describing memory regions that the next kernel
should treat as reserved.

This is useful, e.g., for GICv3 based ARM systems that cannot disable
DMA access to the LPI tables, forcing them to reuse the same memory
region again after a kexec reboot.

Tested-by: Jeremy Linton <jeremy.linton@xxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

NAK

This doesn't belong in -stable, and I'd be interested in understanding
how this got autoselected, and how I can prevent this from happening
again in the future.

It was selected because it's part of a fix for a real issue reported by
users:

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1806766

Besides ubuntu, it is also carried by:

SUSE: https://www.suse.com/support/update/announcement/2019/suse-su-20191530-1/
CentOS: https://koji.mbox.centos.org/koji/buildinfo?buildID=4558

As a way to resolve the reported bug.

Any reason this *shouldn't* be in stable? I'm aware that there might be
dependencies that are not obvious to me, but the solution here is to
take those dependencies as well rather than ignore the process
completely.

--
Thanks,
Sasha



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