Re: WTF: patch "[PATCH] arm/arm64: KVM: Add PSCI version selection API" was seriously submitted to be applied to the 4.16-stable tree?

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Apr 30, 2018 at 04:12:35PM +0100, Marc Zyngier wrote:
> On 30/04/18 16:09, Greg KH wrote:
> > On Mon, Apr 30, 2018 at 04:37:48PM +0200, Christoffer Dall wrote:
> >> On Sun, Apr 29, 2018 at 02:34:45PM +0200, gregkh@linuxfoundation.org wrote:
> >>> The patch below was submitted to be applied to the 4.16-stable tree.
> >>>
> >>> I fail to see how this patch meets the stable kernel rules as found at
> >>> Documentation/process/stable-kernel-rules.rst.
> >>>
> >>> I could be totally wrong, and if so, please respond to 
> >>> <stable@vger.kernel.org> and let me know why this patch should be
> >>> applied.  Otherwise, it is now dropped from my patch queues, never to be
> >>> seen again.
> >>
> >> This patch ensures that current userspace drivers of KVM VMs will fail
> >> migration to targets that do not support spectre/meltdown mitigations.
> >> Without this patch, VMs can be migrated to hosts that do not have
> >> mitigation support without any warning to the system admin.  We
> >> considered this a real security issue as per the stable kernel rules.
> >>
> >> If you disagree, feel free to drop this patch without further
> >> discussion.
> >>
> >> Thanks,
> >> -Christoffer
> >>
> >>>
> >>> ------------------ original commit in Linus's tree ------------------
> >>>
> >>> From 85bd0ba1ff9875798fad94218b627ea9f768f3c3 Mon Sep 17 00:00:00 2001
> >>> From: Marc Zyngier <marc.zyngier@arm.com>
> >>> Date: Sun, 21 Jan 2018 16:42:56 +0000
> >>> Subject: [PATCH] arm/arm64: KVM: Add PSCI version selection API
> >>>
> >>> Although we've implemented PSCI 0.1, 0.2 and 1.0, we expose either 0.1
> >>> or 1.0 to a guest, defaulting to the latest version of the PSCI
> >>> implementation that is compatible with the requested version. This is
> >>> no different from doing a firmware upgrade on KVM.
> >>>
> >>> But in order to give a chance to hypothetical badly implemented guests
> >>> that would have a fit by discovering something other than PSCI 0.2,
> >>> let's provide a new API that allows userspace to pick one particular
> >>> version of the API.
> >>>
> >>> This is implemented as a new class of "firmware" registers, where
> >>> we expose the PSCI version. This allows the PSCI version to be
> >>> save/restored as part of a guest migration, and also set to
> >>> any supported version if the guest requires it.
> >>>
> >>> Cc: stable@vger.kernel.org #4.16
> >>> Reviewed-by: Christoffer Dall <cdall@kernel.org>
> >>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> > 
> > Also, it looks like this applies cleanly to 4.14.y, do you want it there
> > as well?
> Yes. It is likely that any backport of the Spectre series will want this
> as well.

It worked for 4.14.y, but does not apply at all to 4.9.y, which does
have the ARM spectre fixes in it.  If someone could provide a working
backport for there, I would be glad to apply it.

thanks,

greg k-h