Re: [Qemu-arm] [PATCH 03/16] tlb_set_page_with_attrs: Take argument specifying AddressSpace to use

[Edgar E. Iglesias]

On Fri, Nov 06, 2015 at 01:41:54PM +0000, Peter Maydell wrote:
> On 6 November 2015 at 13:27, Edgar E. Iglesias <address@hidden> wrote:
> > On Thu, Nov 05, 2015 at 06:15:45PM +0000, Peter Maydell wrote:
> >> Add an argument to tlb_set_page_with_attrs which allows the target CPU code
> >> to tell the core code which AddressSpace to use.
> >>
> >> The AddressSpace is specified by the index into the array of ASes which
> >> were registered with cpu_address_space_init().
> 
> >> --- a/exec.c
> >> +++ b/exec.c
> >> @@ -445,12 +445,13 @@ MemoryRegion *address_space_translate(AddressSpace 
> >> *as, hwaddr addr,
> >>
> >>  /* Called from RCU critical section */
> >>  MemoryRegionSection *
> >> -address_space_translate_for_iotlb(CPUState *cpu, hwaddr addr,
> >> +address_space_translate_for_iotlb(CPUState *cpu, int asidx, hwaddr addr,
> >>                                    hwaddr *xlat, hwaddr *plen)
> >
> > Does it make sense to replace the CPUState argument with an AddressSpace *
> > and have the callers do the cpu->cpu_ases[asidx]?
> > It would be more consistent and eventually maybe eliminate the need for
> > address_space_translate_for_iotlb in favor of calling 
> > address_space_translate
> > directly?
> 
> We can't accept an arbitrary AddressSpace, it has to be one which is
> embedded in a CPUAddressSpace and which we can thus find the
> memory_dispatch for. So you could pass a CPUAddressSpace*, but not
> an AddressSpace*. But to pass a CPUAddressSpace we would have to
> expose the currently-private-to-exec.c layout of the CPUAddressSpace
> struct. I chose not to do that (and you can see the results elsewhere
> in the patch series, like the function that's basically just "do
> the cs_ases array lookup for me"); there's an argument for making
> the structure more widely available to avoid some of that.

Aha, I see.. Thanks for clarifying.

Cheers,
Edgar