On Mon, 03 Jun 2024 12:52:54 +0100, Sasha Levin sashal@kernel.org wrote:

This is a note to let you know that I've just added the patch titled

KVM: arm64: nv: Add sanitising to VNCR-backed sysregs

to the 6.8-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: kvm-arm64-nv-add-sanitising-to-vncr-backed-sysregs.patch and it can be found in the queue-6.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

commit fbb2bcdc458dd7db3860f85a06e98cc25904d20d Author: Marc Zyngier maz@kernel.org Date: Wed Feb 14 13:18:04 2024 +0000

KVM: arm64: nv: Add sanitising to VNCR-backed sysregs

[ Upstream commit 888f0880702293096619b300150cd7e59fcd9743 ] VNCR-backed "registers" are actually only memory. Which means that there is zero control over what the guest can write, and that it is the hypervisor's job to actually sanitise the content of the backing store. Yeah, this is fun. In order to preserve some form of sanity, add a repainting mechanism that makes use of a per-VM set of RES0/RES1 masks, one pair per VNCR register. These masks get applied on access to the backing store via __vcpu_sys_reg(), ensuring that the state that is consumed by KVM is correct. So far, nothing populates these masks, but stay tuned. Signed-off-by: Marc Zyngier maz@kernel.org Reviewed-by: Joey Gouly joey.gouly@arm.com Link: https://lore.kernel.org/r/20240214131827.2856277-4-maz@kernel.org Signed-off-by: Oliver Upton oliver.upton@linux.dev Stable-dep-of: ce5d2448eb8f ("KVM: arm64: Destroy mpidr_data for 'late' vCPU creation") Signed-off-by: Sasha Levin sashal@kernel.org

Please drop this. It serves no purpose on 6.8 aside from wasting memory. If backporting ce5d2448eb8f is hard due to some conflicts, we'll tackle it ourselves.

Thanks,

M.