In OpenXiangShan NEMU, when Smstateen is enabled, clearing mstateen0.ENVCFG does not correctly restrict access to henvcfg and senvcfg

In OpenXiangShan NEMU, when Smstateen is enabled, clearing mstateen0.ENVCFG does not correctly restrict access to henvcfg and senvcfg. As a result, less-privileged code may read or write these CSRs without the required exception, potentially bypassing intended state-enable based isolation controls in virtualized or multi-privilege environments.