Re: [PATCH v14 2/5] hw/cxl: Make the CXL fixed memory windows devices.

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

On Tue, 10 Jun 2025 07:53:31 +0900
Itaru Kitayama <itaru.kitayama@linux.dev> wrote:

> On Thu, May 29, 2025 at 04:08:01PM +0100, Jonathan Cameron wrote:
> > On Wed, 28 May 2025 12:07:23 +0100
> > Jonathan Cameron <Jonathan.Cameron@huawei.com> wrote:
> >   
> > > Previously these somewhat device like structures were tracked using a list
> > > in the CXLState in each machine.  This is proving restrictive in a few
> > > cases where we need to iterate through these without being aware of the
> > > machine type. Just make them sysbus devices.
> > > 
> > > Restrict them to not user created as they need to be visible to early
> > > stages of machine init given effects on the memory map.
> > > 
> > > This change both simplifies state tracking and enables features needed
> > > for performance optimization and hotness tracking by making it possible
> > > to retrieve the fixed memory window on actions elsewhere in the topology.
> > > 
> > > In some cases the ordering of the Fixed Memory Windows matters.
> > > For those utility functions provide a GSList sorted by the window index.
> > > This ensures that we get consistency across:
> > > - ordering in the command line
> > > - ordering of the host PA ranges
> > > - ordering of ACPI CEDT structures describing the CFMWS.
> > > 
> > > Other aspects don't have this constraint. For those direct iteration
> > > of the underlying hash structures is fine.
> > > 
> > > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>  
> > 
> > I'll not post v15 for a while to give time for review, but I just realized
> > this snippet was in a patch I was carrying on top of this and should have
> > been in this patch.
> > 
> > diff --git a/include/hw/cxl/cxl.h b/include/hw/cxl/cxl.h
> > index a610795c87..de66ab8c35 100644
> > --- a/include/hw/cxl/cxl.h
> > +++ b/include/hw/cxl/cxl.h
> > @@ -46,7 +46,6 @@ typedef struct CXLState {
> >      bool is_enabled;
> >      MemoryRegion host_mr;
> >      unsigned int next_mr_idx;
> > -    GList *fixed_windows;
> >      CXLFixedMemoryWindowOptionsList *cfmw_list;
> >  } CXLState;  
> 
> With this one line removed on top of v14, today's Dave's cxl/next kernel makes
> cxl test suite ran through without a single failure.
> 
> Tested-by: Itaru Kitayama <itaru.kitayama@fujitsu.com>
> 
> Jonathan, Zhi jian of Fujitsu gave you feedback on the QEMU core CXL emulation code, 
> are you still waiting on any other reviewers to take a look at the series v14 (or
> v14-ish)?
No - obviously extra review is always good but I wasn't waiting on any.
Just been distracted so not sent it out yet. Should get it out in next day or two.

Jonathan


> 
> Thanks,
> Itaru.

> 
> >