Re: [Xen-devel] [PATCH v3 0/2] VT-d flush issue

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.12.15 at 09:10, <quan.xu@xxxxxxxxx> wrote:
> For Device-TLB flush error, I think we need to propagated error code.
> For IEC/iotlb/context flush error, if panic is acceptable, we can ignore the 
> propagated error code. BTW, it is very challenge / tricky to handle all
> Of error, and some error is unrecoverable. As mentioned, it looks like 
> rewriting Xen hypervisor.

We're moving in circles. In particular I don't believe this last sentence.
Re-writing many parts of the hypervisor would be required is you
were to return the error to the guest (which technically isn't possible
in many case afaict). Having crashed the guest, you don't need to be
concerned about unrolling previous (partially completed) operations,
so I don't think it's this much of a rewrite.

And just to be clear - I hope you recall that the current approach
taken to the flush issue is already a compromise far away from
where we initially meant the code to move, and it was always
clear that the bad error handling state the code is in is going to
get in the way of this being a simple fix. It's sad that the people
originally having introduced that code can't be held responsible
for fixing this up, but that's a situation we find ourselves in all
the time.

Jan


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