Re: [PATCH for-7.2 14/21] accel/tcg: Hoist get_page_addr_code out of tb_lookup

[Ilya Leoshkevich]

On Wed, 2022-08-17 at 08:15 -0500, Richard Henderson wrote:
> On 8/17/22 06:08, Ilya Leoshkevich wrote:
> > @@ -2243,6 +2250,13 @@ void page_set_flags(target_ulong start,
> > target_ulong end, int flags)
> >               (flags & PAGE_WRITE) &&
> >               p->first_tb) {
> >               tb_invalidate_phys_page(addr, 0);
> > +        } else {
> > +            TranslationBlock *tb;
> > +            int n;
> > +
> > +            PAGE_FOR_EACH_TB(p, tb, n) {
> > +                cpu_tb_jmp_cache_remove(tb);
> > +            }
> >           }
> 
> Here you would use tb_jmp_cache_clear_page(), which should be moved
> out of cputlb.c.

That was actually the first thing I tried.

Unfortunately tb_jmp_cache_clear_page() relies on
tb_jmp_cache_hash_func() returning the same top bits for addresses on
the same page.  This is not the case for qemu-user: there this property
was traded for better hashing with quite impressive performance
improvements (6f1653180f570).