target/riscv: Ensure opcode is saved for all relevant instructions

target/riscv: Ensure opcode is saved for all relevant instructions

We should call decode_save_opc() for all relevant instructions which
can potentially generate a virtual instruction fault or a guest page
fault because generating transformed instruction upon guest page fault
expects opcode to be available. Without this, hypervisor will see
transformed instruction as zero in htinst CSR for guest MMIO emulation
which makes MMIO emulation in hypervisor slow and also breaks nested
virtualization.

Fixes: a9814e3e08d2 ("target/riscv: Minimize the calls to decode_save_opc")
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20230120125950.2246378-5-apatel@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>