Re: [RESEND PATCH v13 3/8] cxl/cdat: Gather DSMAS data for DCD partitions

[Anisa Su <anisa.su887@gmail.com>]

On Tue, Sep 08, 2026 at 09:52:00PM +0100, Jonathan Cameron wrote:
> On Tue,  8 Sep 2026 03:15:07 -0700
> Anisa Su <anisa.su887@gmail.com> wrote:
> 
> > From: Ira Weiny <iweiny@kernel.org>
> > 
> > Additional DCD partition (AKA region) information is contained in the
> > DSMAS CDAT tables, including performance and shareable attributes.
> > 
> > Match DCD partitions with DSMAS tables and store the meta data.
> > 
> > Signed-off-by: Ira Weiny <iweiny@kernel.org>
> > Co-developed-by: Anisa Su <anisa.su@samsung.com>
> > Signed-off-by: Anisa Su <anisa.su@samsung.com>
> > Tested-by: Wonjae Lee <wj28.lee@samsung.com>
> > Tested-by: Junhee Park <jh9934.park@samsung.com>
> > Tested-by: Heesoo Kim <habil.kim@samsung.com>
> > 
> Minor thing inline. I think we can take a bit of refactoring
> you did a little further and end up with simpler code.
> 
> > ---
> >  drivers/cxl/core/cdat.c   | 32 +++++++++++++++++++++++++-------
> >  drivers/cxl/core/hdm.c    |  1 +
> >  drivers/cxl/core/mbox.c   |  9 +++++++++
> >  drivers/cxl/core/memdev.c | 17 ++++++++++-------
> >  drivers/cxl/cxlmem.h      |  2 ++
> >  include/cxl/cxl.h         |  4 ++++
> >  6 files changed, 51 insertions(+), 14 deletions(-)
> > 
> > diff --git a/drivers/cxl/core/cdat.c b/drivers/cxl/core/cdat.c
> > index 5c9f07262513..05058d4520f2 100644
> > --- a/drivers/cxl/core/cdat.c
> > +++ b/drivers/cxl/core/cdat.c
> > @@ -17,6 +17,7 @@ struct dsmas_entry {
> >  	struct access_coordinate cdat_coord[ACCESS_COORDINATE_MAX];
> >  	int entries;
> >  	int qos_class;
> > +	bool shareable;
> >  };
> >  
> >  static u32 cdat_normalize(u16 entry, u64 base, u8 type)
> > @@ -74,6 +75,8 @@ static int cdat_dsmas_handler(union acpi_subtable_headers *header, void *arg,
> >  		return -ENOMEM;
> >  
> >  	dent->handle = dsmas->dsmad_handle;
> > +	/* Shareable is CDAT 1.03 and later, DSMAS Flags bit 3 */
> > +	dent->shareable = dsmas->flags & ACPI_CDAT_DSMAS_SHAREABLE;
> >  	dent->dpa_range.start = le64_to_cpu((__force __le64)dsmas->dpa_base_address);
> >  	dent->dpa_range.end = le64_to_cpu((__force __le64)dsmas->dpa_base_address) +
> >  			      le64_to_cpu((__force __le64)dsmas->dpa_length) - 1;
> > @@ -266,18 +269,33 @@ static void cxl_memdev_set_qos_class(struct cxl_dev_state *cxlds,
> >  		bool found = false;
> >  
> >  		for (int i = 0; i < cxlds->nr_partitions; i++) {
> > -			struct resource *res = &cxlds->part[i].res;
> > +			struct cxl_dpa_partition *part = &cxlds->part[i];
> >  			struct range range = {
> > -				.start = res->start,
> > -				.end = res->end,
> > +				.start = part->res.start,
> > +				.end = part->res.end,
> >  			};
> >  
> > -			if (range_contains(&range, &dent->dpa_range)) {
> > -				update_perf_entry(dev, dent,
> > -						  &cxlds->part[i].perf);
> > -				found = true;
> > +			if (!range_contains(&range, &dent->dpa_range))
> > +				continue;
> > +
> > +			found = true;
> > +			/*
> > +			 * part->handle is from Get DC Config, dent->handle
> > +			 * from the CDAT DSMAS entry.
> > +			 */
> > +			if (part->mode == CXL_PARTMODE_DYNAMIC_RAM_1 &&
> > +			    dent->handle != part->handle) {
> > +				dev_warn(dev,
> > +					 "DSMAD handle mismatch: %pra has %u, DSMAS %pra has %u\n",
> > +					 &range, part->handle,
> > +					 &dent->dpa_range, dent->handle);
> >  				break;
> 
> For the error path I'd just return here. Maybe there is more after this loop
> in future patches that make it useful to break instead?
> 
> >  			}
> > +
> > +			update_perf_entry(dev, dent, &part->perf);
> > +			if (part->mode == CXL_PARTMODE_DYNAMIC_RAM_1)
> > +				part->shareable = dent->shareable;
> > +			break;
> 
> Come to think of it, can return in this path too.  Then you don't need the
> local variable found.
> 
Ah the break in both spots is so we print a debug message if no
partition is found matching the dsmas entry:

if (!found)
	dev_dbg(dev, "no partition for dsmas dpa: %pra\n",
		&dent->dpa_range);

It got cut off in the diff.

> >  		}
> 
> >  
> >  		if (!found)