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

["Jan Beulich" <jbeulich@xxxxxxxx>]

>>> 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.

Jan


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