On Fri, 19 Dec 2025 18:11:07 +0000
Ben Horgan [off-list ref] wrote:

When kvm enables or disables MPAM traps to EL2 it clears all other bits in
MPAM2_EL2.  Notably, it clears the partition ids (PARTIDs) and performance
monitoring groups (PMGs). Avoid changing these bits in anticipation of
adding support for MPAM in the kernel. Otherwise, on a VHE system with the
host running at EL2 where MPAM2_EL2 and MPAM1_EL1 access the same register,
any attempt to use MPAM to monitor or partition resources for kernel space
would be foiled by running a KVM guest. Additionally, MPAM2_EL2.EnMPAMSM is
always set to 0 which causes MPAMSM_EL1 to always trap. Keep EnMPAMSM set
to 1 when not in a guest so that the kernel can use MPAMSM_EL1.

Signed-off-by: Ben Horgan <ben.horgan@arm.com>

Seems to match what I'd expect from the spec, so LGTM.
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>