All accessors of kvm_vcpu_arch::mp_state should be {READ,WRITE}_ONCE(), since readers of the mp_state don't acquire the mp_state_lock. Nonetheless, kvm_psci_vcpu_on() updates the mp_state without using WRITE_ONCE(). So, fix the code to update the mp_state using WRITE_ONCE. Signed-off-by: Reiji Watanabe <reijiw@google.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20230419021852.2981107-3-reijiw@google.com