Re: [Xen-devel] [PATCH v12 1/4] x86emul: New return code for unimplemented instruction

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.09.17 at 11:16, <ppircalabu@xxxxxxxxxxxxxxx> wrote:
> @@ -7750,6 +7742,9 @@ x86_emulate(
>      unimplemented_insn:
>          rc = X86EMUL_UNIMPLEMENTED;
>          goto done;
> +    unrecognized_insn:
> +        rc = X86EMUL_UNRECOGNIZED;
> +        goto done;
>      }
> Do you find this approach OK?

Yes, that's reasonable I think.

> Do you think adding a "TODO:" comment can make things more clear?
> e.g.:
>    * The current instruction's opcode is not valid.
>    * If this error code is returned by a function, an #UD trap should e
>    * raised by the final consumer of it.
> +  *
> +  * TODO: For the moment X86EMUL_UNRECOGNIZED and 86EMUL_UNIMPLEMENTED
> +  * can be used interchangeably.
>   */

Something along these lines, yes, plus an indication that the #UD
raising therefore also isn't strictly being expected for now.

Jan


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