Re: [PATCH v2 05/21] cxl: Add callback to parse the DSMAS subtables from CDAT

[Dave Jiang <dave.jiang@xxxxxxxxx>]

On 3/28/23 5:20 PM, Alison Schofield wrote:
> On Mon, Mar 27, 2023 at 02:44:32PM -0700, Dave Jiang wrote:
> > Provide a callback function to the CDAT parser in order to parse the Device
> > Scoped Memory Affinity Structure (DSMAS). Each DSMAS structure contains the
> > DPA range and its associated attributes in each entry. See the CDAT
> > specification for details.
>
> Are we going away from offering spec section numbers or links?

Ok I'll add.

> > Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
> >
> > ---
> > v2:
> > - Add DSMAS table size check. (Lukas)
> > - Use local DSMAS header for LE handling.
> > - Remove dsmas lock. (Jonathan)
> > - Fix handle size (Jonathan)
> > - Add LE to host conversion for DSMAS address and length.
> > - Make dsmas_list local
> > ---
> >   drivers/cxl/core/cdat.c |   26 ++++++++++++++++++++++++++
> >   drivers/cxl/cxl.h       |    1 +
> >   drivers/cxl/cxlpci.h    |   18 ++++++++++++++++++
> >   drivers/cxl/port.c      |   24 ++++++++++++++++++++++++
> >   4 files changed, 69 insertions(+)
> >
> > diff --git a/drivers/cxl/core/cdat.c b/drivers/cxl/core/cdat.c
> > index 210f4499bddb..d068609fb6f9 100644
> > --- a/drivers/cxl/core/cdat.c
> > +++ b/drivers/cxl/core/cdat.c
> > @@ -98,3 +98,29 @@ int cdat_table_parse_sslbis(struct cdat_header *table,
> >   	return cdat_table_parse_entries(CDAT_TYPE_SSLBIS, table, &proc);
> >   }
> >   EXPORT_SYMBOL_NS_GPL(cdat_table_parse_sslbis, CXL);
> > +
> > +int cxl_dsmas_parse_entry(struct cdat_entry_header *header, void *arg)
> > +{
> > +	struct cdat_dsmas *dsmas = (struct cdat_dsmas *)(header);
> > +	struct list_head *dsmas_list = (struct list_head *)arg;
>
> cast from void unnecessary ?

Ok will remove

> > +	struct dsmas_entry *dent;
> > +
> > +	if (dsmas->hdr.length != sizeof(*dsmas)) {
> > +		pr_warn("Malformed DSMAS table length: (%lu:%u)\n",
> > +			 (unsigned long)sizeof(*dsmas), dsmas->hdr.length);
> > +		return -EINVAL;
> > +	}
> > +
> > +	dent = kzalloc(sizeof(*dent), GFP_KERNEL);
> > +	if (!dent)
> > +		return -ENOMEM;
> > +
> > +	dent->handle = dsmas->dsmad_handle;
> > +	dent->dpa_range.start = le64_to_cpu(dsmas->dpa_base_address);
> > +	dent->dpa_range.end = le64_to_cpu(dsmas->dpa_base_address) +
> > +			      le64_to_cpu(dsmas->dpa_length) - 1;
> > +	list_add_tail(&dent->list, dsmas_list);
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_NS_GPL(cxl_dsmas_parse_entry, CXL);
> > diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> > index cc3309794b45..9d0e22fe72c0 100644
> > --- a/drivers/cxl/cxl.h
> > +++ b/drivers/cxl/cxl.h
> > @@ -8,6 +8,7 @@
> >   #include <linux/bitfield.h>
> >   #include <linux/bitops.h>
> >   #include <linux/log2.h>
> > +#include <linux/list.h>
> >   #include <linux/io.h>
> >   
> >   /**
> > diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h
> > index 45e2f2bf5ef8..9a2468a93d83 100644
> > --- a/drivers/cxl/cxlpci.h
> > +++ b/drivers/cxl/cxlpci.h
> > @@ -104,6 +104,22 @@ struct cdat_subtable_entry {
> >   	enum cdat_type type;
> >   };
> >   
> > +struct dsmas_entry {
> > +	struct list_head list;
> > +	struct range dpa_range;
> > +	u8 handle;
> > +};
> > +
> > +/* Sub-table 0: Device Scoped Memory Affinity Structure (DSMAS) */
> > +struct cdat_dsmas {
> > +	struct cdat_entry_header hdr;
> > +	u8 dsmad_handle;
> > +	u8 flags;
> > +	__u16 reserved;
> > +	__le64 dpa_base_address;
> > +	__le64 dpa_length;
> > +} __packed;
> > +
> >   int devm_cxl_port_enumerate_dports(struct cxl_port *port);
> >   struct cxl_dev_state;
> >   int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm,
> > @@ -119,4 +135,6 @@ int cdat_table_parse_##x(struct cdat_header *table, \
> >   cdat_table_parse(dsmas);
> >   cdat_table_parse(dslbis);
> >   cdat_table_parse(sslbis);
> > +
> > +int cxl_dsmas_parse_entry(struct cdat_entry_header *header, void *arg);
> >   #endif /* __CXL_PCI_H__ */
> > diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
> > index 60a865680e22..c8136797d528 100644
> > --- a/drivers/cxl/port.c
> > +++ b/drivers/cxl/port.c
> > @@ -57,6 +57,16 @@ static int discover_region(struct device *dev, void *root)
> >   	return 0;
> >   }
> >   
> > +static void dsmas_list_destroy(struct list_head *dsmas_list)
> > +{
> > +	struct dsmas_entry *dentry, *n;
> > +
> > +	list_for_each_entry_safe(dentry, n, dsmas_list, list) {
> > +		list_del(&dentry->list);
> > +		kfree(dentry);
> > +	}
> > +}
> > +
> >   static int cxl_switch_port_probe(struct cxl_port *port)
> >   {
> >   	struct cxl_hdm *cxlhdm;
> > @@ -131,9 +141,23 @@ static int cxl_endpoint_port_probe(struct cxl_port *port)
> >   static int cxl_port_probe(struct device *dev)
> >   {
> >   	struct cxl_port *port = to_cxl_port(dev);
> > +	int rc;
> >   
> >   	/* Cache the data early to ensure is_visible() works */
> >   	read_cdat_data(port);
> > +	if (port->cdat.table) {
> > +		if (is_cxl_endpoint(port)) {
>
> How about reducing indentation w:
> 	if ((port->cdat.table) && (is_cxl_endpoint(port))

Yes. I got a little disoriented around here from the v6.2 to v6.3 rebase 
where this function changed drastically. In fact I think I'll move this 
block under the endpoint check below to avoid another endpoint check.

> > +			LIST_HEAD(dsmas_list);
> > +
> > +			rc = cdat_table_parse_dsmas(port->cdat.table,
> > +						    cxl_dsmas_parse_entry,
> > +						    (void *)&dsmas_list);
> > +			if (rc < 0)
> > +				dev_warn(dev, "Failed to parse DSMAS: %d\n", rc);
> > +
> > +			dsmas_list_destroy(&dsmas_list);
> > +		}
> > +	}
> >   
> >   	if (is_cxl_endpoint(port))
> >   		return cxl_endpoint_port_probe(port);