target/riscv/tcg: handle profile MISA bits

target/riscv/tcg: handle profile MISA bits

The profile support is handling multi-letter extensions only. Let's add
support for MISA bits as well.

We'll go through every known MISA bit. If the profile doesn't declare
the bit as mandatory, ignore it. Otherwise, set the bit in env->misa_ext
and env->misa_ext_mask.

Now that we're setting profile MISA bits, one can use the rv64i CPU to boot
Linux using the following options:

-cpu rv64i,rva22u64=true,rv39=true,s=true,zifencei=true

In the near future, when rva22s64 (where, 's', 'zifencei' and sv39 are
mandatory), is implemented, rv64i will be able to boot Linux loading
rva22s64 and no additional flags.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20231218125334.37184-14-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>