[PATCH v2] drm/i915/gvt: add RING_INSTDONE and SC_INSTDONE mmio handler in GVT-g

[Zhenyu Wang]

On 2017.05.19 23:48:34 +0800, Weinan Li wrote:
> kernel hangcheck needs to check RING_INSTDONE and SC_INSTDONE registers'
> state to know if hardware is still running. In GVT-g environment, we need
> to emulate these registers changing for all the guests although they are
> not render owner. Here we return the physical state for all the guests,
> then if INSTDONE is changing guest can know hardware is still running
> although its workload is pending.
> 
> Read INSTDONE isn't one correct way to know if guest trigger gfx reset,
> especially with Linux guest, it will read ACTH first, then check INSTDONE
> and SUBSLICE registers to check if hardware is still running, at last
> trigger gfx reset when it finds all the registers is frozen. In Windows
> guest, read INSTDONE usually happens when OS detect TDR.
> 
> With the difference between Windows and Linux guest, "disable_warn_untrack"
> may let debug log run into wrong state(Linux guest trigger hangcheck
> with no ACTHD changed, then check INSTDONE), but actually there is no TDR
> happened.
> 
> The new policy is always WARN with untrack MMIO r/w. Bad effect is many
> noisy untrack mmio warning logs exist when real TDR happen. Even so you can
> control the log output or not by setting the debug mask bit.
> 
> v2: remove log in instdone_mmio_read
> 

pushed, thanks!

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Open Source Technology Center, Intel ltd.

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