Re: [PATCH V2 1/1] target/loongarch: Fixed tlb huge page loading issue

[Richard Henderson]

On 3/5/24 17:52, lixianglai wrote:
> The LDDIR_PS variable is not described in detail in the manual, but is only an 
> intermediate variable to assist in page size calculation during tcg simulation.

This is exactly why I believe adding this intermediate variable is wrong.

What happens if LDPTE is *not* preceded by LDDIR?  It's not the usual way a tlb fill 
routine works, but *something* should happen if you construct a valid huge page tlb entry 
by hand and pass it directly to LDPTE.

With your implementation, this will not work because lddir_ps will not be initialized. 
But I expect that on real hardware it would work.

If this does not work on real hardware, then there *is* some heretofore undocumented 
hardware state.  If so, then we need a description of this state from the hardware 
engineers -- the documentation of LDDIR and LDPTE need updating.  Finally, this new 
hardware state needs to be added to the migration state.


r~