target/riscv: Simplify the check in hmode to reuse the check in riscv_csrrw_check

Just add 1 to the effective privledge level when in HS mode, then reuse
the check of 'effective_priv < csr_priv' in riscv_csrrw_check to replace
the privilege level related check in hmode. Then, hmode will only check
whether H extension is supported.

When accessing Hypervior CSRs:
   1) If accessing from M privilege level, the check of
'effective_priv< csr_priv' passes, returns hmode(...) which will return
RISCV_EXCP_ILLEGAL_INST when H extension is not supported and return
RISCV_EXCP_NONE otherwise.
   2) If accessing from HS privilege level, effective_priv will add 1,
the check passes and also returns hmode(...) too.
   3) If accessing from VS/VU privilege level, the check fails, and
returns RISCV_EXCP_VIRT_INSTRUCTION_FAULT
   4) If accessing from U privilege level, the check fails, and returns
RISCV_EXCP_ILLEGAL_INST

Signed-off-by: Weiwei Li <liweiwei@iscas.ac.cn>
Signed-off-by: Junqiang Wang <wangjunqiang@iscas.ac.cn>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Message-Id: <20220718130955.11899-7-liweiwei@iscas.ac.cn>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

0 files changed, 0 insertions, 0 deletions