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Re: [Xen-devel] [PATCH 04/10] xen/arm: vgic-v3: Don't check the size when we ignore the write/read as zero

On 21/01/15 12:36, Ian Campbell wrote:
> On Wed, 2015-01-21 at 12:28 +0000, Julien Grall wrote:
>>> 3) Accesses which are valid but which do not correctly emulate according
>>> to the features of the virtual gic which we are exposing can log if we
>>> think it is useful to do so.
>> I gave a look to the code. We have few registers we don't correctly
>> emulate. The current behavior seems to be inconsistent, we either inject
>> a data abort (such as ICPENDR) or ignore the error (such as ICACTIVER).
>> Shall we take a domain_crash approach (as bad_width) or inject a data abort?
> I think for these cases since we do update and/or return
> rank->iactive/ipend a debug log and continue is appropriate.
> Assuming we do need to do something more than track the status of
> i{active,pend}, which I expect we do -- e.g. to cancel or inject as
> appropriate.

This code is actually buggy as we never use those fields. I have a patch
to drop iactive/ipend fields as we will unlikely handle ACTIVE/PENDING
status via those bit. We already track in different way as we already
have tracking per vIRQ.

My plan was to replace them with an error log and maybe a data abort.
If you think a debug message is enough, I could go this way. Though, it
may be more difficult for a developer to find the actual error if there
is may logs.


Julien Grall

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