Re: [PATCH v4 04/14] cxl/region: Add @hpa_range argument to function cxl_calc_interleave_pos()

Robert Richter
2025-11-11T11:28:20Z

On 03.11.25 19:04:34, Alison Schofield wrote:
> On Mon, Nov 03, 2025 at 07:47:45PM +0100, Robert Richter wrote:
> > cxl_calc_interleave_pos() uses the endpoint decoder's HPA range to
> > determine its interleaving position. This requires the endpoint
> > decoders to be an SPA, which is not the case for systems that need
> > address translation.
> >
> > Add a separate @hpa_range argument to function
> > cxl_calc_interleave_pos() to specify the address range. Now it is
> > possible to pass the SPA translated address range of an endpoint
> > decoder to function cxl_calc_interleave_pos().
> >
> > Refactor only, no functional changes.
> >
> > Patch is a prerequisite to implement address translation.
> >
> > Reviewed-by: Gregory Price <gourry@gourry.net>
> > Signed-off-by: Robert Richter <rrichter@amd.com>
> > ---
> > drivers/cxl/core/region.c | 13 +++++++------
> > 1 file changed, 7 insertions(+), 6 deletions(-)
>
> snip
>
> > @@ -2094,7 +2095,7 @@ static int cxl_region_attach(struct cxl_region *cxlr,
> > struct cxl_endpoint_decoder *cxled = p->targets[i];
> > int test_pos;
> >
> > - test_pos = cxl_calc_interleave_pos(cxled);
> > + test_pos = cxl_calc_interleave_pos(cxled, &cxlr->hpa_range);
>
> This is accessing the new hpa_range that Patch 2/14 started storing in
> struct cxl_region. It stores it only for auto-regions and this is
> a user created region path.
>
> So the fixup is actually in Patch 2 - but this is the why. It shows
> up as a bunch of dev_errs() from find_pos_and_ways() running unit
> tests that create regions.

See my response to patch 2. I have a fix that properly initializes the
hpa_range now.

Thanks,

-Robert

>
>
> > dev_dbg(&cxled->cxld.dev,
> > "Test cxl_calc_interleave_pos(): %s test_pos:%d cxled->pos:%d\n",
> > (test_pos == cxled->pos) ? "success" : "fail",
> > --
> > 2.47.3
> >