On ke, 2017-01-11 at 12:14 +0000, Chris Wilson wrote:
> When switching between contexts using the aliasing_ppgtt, the VM is
> shared. We don't need to reload the PD registers unless they are dirty.
>
> Martin Peres reported an issue that looks like corruption between
> Haswell context switches, bisecting to commit f9326be5f1d3 ("drm/i915:
> Rearrange switch_context to load the aliasing ppgtt on first use").
> Switching between the same mm (the aliasing_ppgtt is used for all
> contexts in this case) should be a nop, but appears to trigger some
> side-effects in the context switch. However, as we know the switch
> is redundant in this case, we can skip it and continue to ignore the
> issue until somebody feels strong enough to investigate full-ppgtt on
> gen7 again!
>
> Fixes: f9326be5f1d3 ("drm/i915: Rearrange switch_context to load the aliasing ppgtt on first use")
> Reported-by: Martin Peres <martin.peres@xxxxxxxxxxxxxxx>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Martin Peres <martin.peres@xxxxxxxxxxxxxxx>
Code looks good, could use the T-b's to verify.
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Regards, Joonas
--
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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