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Re: [Xen-devel] [PATCH v13 1/3] x86emul: New return code for unimplemented instruction

>>> On 25.09.17 at 14:03, <ppircalabu@xxxxxxxxxxxxxxx> wrote:
> Enforce the distinction between an instruction not implemented by the
> emulator and the failure to emulate that instruction by defining a new
> return code, X86EMUL_UNIMPLEMENTED.
> This value should only be returned by the core emulator only if it fails to
> properly decode the current instruction's opcode, and not by any of other
> functions, such as the x86_emulate_ops or the hvm_io_ops callbacks.
> e.g. hvm_process_io_intercept should not return X86EMUL_UNIMPLEMENTED.
> The return value of this function depends on either the return code of
> one of the hvm_io_ops handlers (read/write) or the value returned by
> hvm_copy_guest_from_phys / hvm_copy_to_guest_phys.
> Similary, none of this functions should return X86EMUL_UNIMPLEMENTED.
>  - hvm_io_intercept
>  - hvmemul_do_io
>  - hvm_send_buffered_ioreq
>  - hvm_send_ioreq
>  - hvm_broadcast_ioreq
>  - hvmemul_do_io_buffer
>  - hvmemul_validate
> Also the behavior of hvm_emulate_one_insn and vmx_realmode_emulate_one
> was modified to generate an Invalid Opcode trap when X86EMUL_UNRECOGNIZED
> is returned by the emulator instead of just crash the domain.
> Signed-off-by: Petre Pircalabu <ppircalabu@xxxxxxxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

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