On 27.06.2017 18:10, David Hildenbrand wrote:
> STFL bit 4 and 5 are just indications to the guest, which TLB entries an
> IDTE call will clear. These are performance indicators for the guest.
>
> STFL bit 4:
> INVALIDATE DAT TABLE ENTRY (IDTE) performs
> the invalidation-and-clearing operation by
> selectively clearing TLB segment-table entries
> when a segment-table entry or entries are
> invalidated. IDTE also performs the clearing-by-
> ASCE operation. Unless bit 4 is one, IDTE simply
> purges all TLBs. Bit 3 is one if bit 4 is one.
>
> We can simply set STFL bit 4 ("idtes") and still purge the complete TLB.
> Purging more than advertised is never bad. E.g. Linux doesn't even care
> about this bit. We can optimized this later.
Not sure, but why do we need this bit in add_qemu_cpu_model_features()
if Linux does not care about it? We will get it automatically once we
support the z9 in TCG...
Thomas
