arch-riscv: fault on mstatus accesses from lower privilege modes.

Change-Id: If2e35445770eaa52f5af6f9ef02fb5e11bef8da4
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/25652
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
1 file changed