Re: [PATCH 15/17] m68k: Implement the new page table range API

[Matthew Wilcox <willy@infradead.org>]

On Thu, Feb 16, 2023 at 01:59:44PM +1300, Michael Schmitz wrote:
> Matthew,
> 
> On 16/02/23 09:09, Matthew Wilcox (Oracle) wrote:
> > Add set_ptes(), update_mmu_cache_range(), flush_icache_pages() and
> > flush_dcache_folio().  I'm not entirely certain that the 040/060 case
> > in __flush_pages_to_ram() is correct.
> 
> I'm pretty sure you need to iterate to hit each of the pages - the code as
> is will only push cache entries for the first page.
> 
> Quoting the 040 UM:
> 
> "Both instructions [cinv, cpush] allow operation on a single cache line, all
> cache lines in a specific page, or an entire cache, and can select one or
> both caches for the operation. For line and page operations, a physical
> address in an address register specifies the memory address."

I actually found that!  What I didn't find was how to tell if this
cpush insn is the one which is operating on a single cache line,
a single page, or the entire cache.

So I should do a loop around this asm and call it once for each page
we're flushing?