Re: [Xen-devel] [PATCH v2] x86/hvm: fix interaction between internal and external emulation

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 01/12/17 16:55, Jan Beulich wrote:
>>>> Julien Grall <julien.grall@xxxxxxxxxx> 12/01/17 5:14 PM >>>
>> On 30/11/17 14:28, Jan Beulich wrote:
>>>>>> On 28.11.17 at 15:05, <paul.durrant@xxxxxxxxxx> wrote:
>>>> A call to handle_hvm_io_completion() is needed for completing I/O
>>>> that requires external emulation. Such completion should be requested when
>>>> hvm_vcpu_io_need_completion() returns true after hvm_emulate_once() has
>>>> completed. This is indicative of the underlying I/O emulation having
>>>> returned X86EMUL_RETRY and hence a re-emulation of the instruction is
>>>> needed to pick up the result of the I/O.
>>>>
>>>> A call to handle_hvm_io_completion() is NOT needed when the underlying
>>>> I/O has not returned X86EMUL_RETRY since there will be no result to pick
>>>> up. Hence it bogus to request such completion when mmio_retry is set,
>>>> since this can only happen if the underlying I/O emulation has returned
>>>> X86EMUL_OKAY (meaning the I/O has completed successfully).
>>>>
>>>> Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>>>> Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
>>>> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
>>> Hmm, I notice Paul didn't Cc you on this one - despite it getting late,
>>> this is still something to be considered for 4.10. It's certainly going
>>> to be a backporting candidate.
>> Release-acked-by: Julien Grall <julien.grall@xxxxxxxxxx>
> Thanks.
>
>> Could this be committed today?
> Not by me; I'm not in the office anymore. Perhaps Andrew could, together with
> the other (his) one you've sent an ack for.

I'll get these sorted, and put onto the 4.10 branch.

~Andrew

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