Re: [PATCH v3 11/20] xen/riscv: implement function to map memory in guest p2m

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

On 8/11/25 9:28 AM, Jan Beulich wrote:

> On 08.08.2025 15:46, Oleksii Kurochko wrote:
> > On 8/5/25 5:20 PM, Jan Beulich wrote:
> > > On 31.07.2025 17:58, Oleksii Kurochko wrote:
> > > > +/* Unlock the flush and do a P2M TLB flush if necessary */
> > > > +void p2m_write_unlock(struct p2m_domain *p2m)
> > > > +{
> > > > +    /*
> > > > +     * The final flush is done with the P2M write lock taken to avoid
> > > > +     * someone else modifying the P2M wbefore the TLB invalidation has
> > > >           
> > > Nit: Stray 'w'.
> > >
> > > > +     * completed.
> > > > +     */
> > > > +    p2m_tlb_flush_sync(p2m);
> > > >           
> > > Wasn't the plan to have this be conditional?
> > >         
> > Not really, probably, I misunderstood you before.
> >
> > Previously, I only had|p2m_force_tlb_flush_sync()| here, instead of
> > |p2m_tlb_flush_sync()|, and the latter includes a condition check on
> > |p2m->need_flush|.
> >       
> Just to re-iterate my point: Not every unlock will require a flush. Hence
> why I expect the flush to be conditional upon there being an indication
> that some change was done that requires flushing.
>
>     
The flush is actually conditional; the condition is inside
p2m_tlb_flush_sync():
  void p2m_tlb_flush_sync(struct p2m_domain *p2m)
  {
    if ( p2m->need_flush )
      p2m_force_tlb_flush_sync(p2m);
  }

~ Oleksii