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

[Sasha Levin]

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