Re: [PATCH] cxl: Add hpa_to_spa to the root decoder callback operations

[Alison Schofield <alison.schofield@intel.com>]

On Fri, Jul 11, 2025 at 05:45:30PM +0100, Jonathan Cameron wrote:
> On Wed, 9 Jul 2025 13:07:46 -0700
> Dave Jiang <dave.jiang@intel.com> wrote:
> 
> > Remove cxl_hpa_to_spa_fn callback from cxl root decoder and add the
> > callback function to cxl_decoder_ops. Refactor to group all the root
> > decoder callbacks together.
> > 
> > Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> 
> Question inline about mixture of types of CFMWS entry.
> 
> > ---
> >  drivers/cxl/acpi.c        |  9 +++++++--
> >  drivers/cxl/core/port.c   |  2 +-
> >  drivers/cxl/core/region.c | 11 ++++++++---
> >  drivers/cxl/cxl.h         | 13 ++++++++-----
> >  4 files changed, 24 insertions(+), 11 deletions(-)
> > 
> > diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> > index 48478bc406ee..9f7e2a49dc5a 100644
> > --- a/drivers/cxl/acpi.c
> > +++ b/drivers/cxl/acpi.c
> > @@ -20,6 +20,10 @@ static const guid_t acpi_cxl_qtg_id_guid =
> >  	GUID_INIT(0xF365F9A6, 0xA7DE, 0x4071,
> >  		  0xA6, 0x6A, 0xB4, 0x0C, 0x0B, 0x4F, 0x8E, 0x52);
> >  
> > +static u64 cxl_default_hpa_to_spa(struct cxl_root_decoder *cxlrd, u64 hpa)
> > +{
> > +	return hpa;
> > +}
> >  
> >  static u64 cxl_xor_hpa_to_spa(struct cxl_root_decoder *cxlrd, u64 hpa)
> >  {
> > @@ -342,8 +346,9 @@ static int cxl_acpi_get_extended_linear_cache_size(struct resource *backing_res,
> >  	return hmat_get_extended_linear_cache_size(backing_res, nid, size);
> >  }
> >  
> > -static const struct cxl_rd_ops acpi_rd_ops = {
> > +static struct cxl_rd_ops acpi_rd_ops = {
> >  	.get_extended_linear_cache_size = cxl_acpi_get_extended_linear_cache_size,
> > +	.hpa_to_spa = cxl_default_hpa_to_spa,
> >  };
> >  
> >  DEFINE_FREE(put_cxlrd, struct cxl_root_decoder *,
> > @@ -425,7 +430,7 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
> >  	cxlrd->qos_class = cfmws->qtg_id;
> >  
> >  	if (cfmws->interleave_arithmetic == ACPI_CEDT_CFMWS_ARITHMETIC_XOR)
> > -		cxlrd->hpa_to_spa = cxl_xor_hpa_to_spa;
> > +		cxlrd->ops->hpa_to_spa = cxl_xor_hpa_to_spa;
> 
> What happens if we have a mixture for different CMWS entries?
> Some xor, some not.

A separate root decoder is created for each CFMWS entry, so no
conflict. Is that what you're wondering?


> 
> >  
> >  	rc = cxl_decoder_add(cxld, target_map);
> >  	if (rc)
>