Re: [PATCH v2 3/3] drm/i915: Track OACONTROL register enable/disable during parsing

Kenneth Graunke
2014-03-28T17:37:05Z

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On 03/28/2014 10:21 AM, bradley.d.volkin@intel.com wrote:
> From: Brad Volkin <bradley.d.volkin@intel.com>
>
> There is some thought that the data from the performance counters enabled
> via OACONTROL should only be available to the process that enabled counting.
> To limit snooping, require that any batch buffer which sets OACONTROL to a
> non-zero value also sets it back to 0 before the end of the batch.
>
> This requires limiting OACONTROL writes to happen via MI_LOAD_REGISTER_IMM
> so that we can access the value being written. This should be in line with
> the expected use case for writing OACONTROL.
>
> v2: Drop an unnecessary '? true : false'
>
> Cc: Kenneth Graunke <kenneth@whitecape.org>
> Signed-off-by: Brad Volkin <bradley.d.volkin@intel.com>

I still don't see any rationale for prohibiting LRM - there's zero
security benefit, and you can write to every other register with either
LRI or LRM, so it's just extra inconsistency. But, Daniel.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

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