[PATCH V6 10/10] cxl/cdat: Parse out DSMAS data from CDAT table

ira.weiny
2022-02-01T07:20:43Z

From: Ira Weiny <ira.weiny@intel.com>

CXL memory devices need the information in the Device Scoped Memory
Affinity Structure (DSMAS). This information is contained within the
CDAT table buffer which is already read and cached.

Parse and cache DSMAS data from the CDAT table. Store this data in
unmarshaled struct dsmas data structures for ease of use.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes from V5
Fix up sparse warnings
Split out cdat_hdr_valid()
Update cdat_hdr_valid()
Remove revision and cs field parsing
There is no point in these
Add seq check and debug print.
From Jonathan
Add spaces around '+' and '/'
use devm_krealloc() for dmas_ary

Changes from V4
New patch
---
drivers/cxl/cdat.h | 21 ++++++++++++
drivers/cxl/core/memdev.c | 70 +++++++++++++++++++++++++++++++++++++++
2 files changed, 91 insertions(+)

diff --git a/drivers/cxl/cdat.h b/drivers/cxl/cdat.h
index a7725d26f2d2..f8c126190d18 100644
--- a/drivers/cxl/cdat.h
+++ b/drivers/cxl/cdat.h
@@ -83,17 +83,38 @@
#define CDAT_SSLBIS_ENTRY_PORT_Y(entry, i) (((entry)[4 + (i) * 2] & 0xffff0000) >> 16)
#define CDAT_SSLBIS_ENTRY_LAT_OR_BW(entry, i) ((entry)[4 + (i) * 2 + 1] & 0x0000ffff)

+/**
+ * struct cxl_dsmas - host unmarshaled version of DSMAS data
+ *
+ * As defined in the Coherent Device Attribute Table (CDAT) specification this
+ * represents a single DSMAS entry in that table.
+ *
+ * @dpa_base: The lowest DPA address associated with this DSMAD
+ * @dpa_length: Length in bytes of this DSMAD
+ * @non_volatile: If set, the memory region represents Non-Volatile memory
+ */
+struct cxl_dsmas {
+ u64 dpa_base;
+ u64 dpa_length;
+ /* Flags */
+ u8 non_volatile:1;
+};
+
/**
* struct cxl_cdat - CXL CDAT data
*
* @table: cache of CDAT table
* @length: length of cached CDAT table
* @seq: Last read Sequence number of the CDAT table
+ * @dsmas_ary: Array of DSMAS entries as parsed from the CDAT table
+ * @nr_dsmas: Number of entries in dsmas_ary
*/
struct cxl_cdat {
void *table;
size_t length;
u32 seq;
+ struct cxl_dsmas *dsmas_ary;
+ int nr_dsmas;
};

#endif /* !__CXL_CDAT_H__ */
diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index 11d721c56f08..32342a15e991 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -6,6 +6,7 @@
#include <linux/idr.h>
#include <linux/pci.h>
#include <cxlmem.h>
+#include "cdat.h"
#include "core.h"

static DECLARE_RWSEM(cxl_memdev_rwsem);
@@ -386,6 +387,71 @@ static int read_cdat_data(struct cxl_memdev *cxlmd,
return rc;
}

+static int parse_dsmas(struct cxl_memdev *cxlmd)
+{
+ struct cxl_dsmas *dsmas_ary = NULL;
+ u32 *data = cxlmd->cdat.table;
+ int bytes_left = cxlmd->cdat.length;
+ int nr_dsmas = 0;
+
+ if (!data)
+ return -ENXIO;
+
+ /* Skip header */
+ data += CDAT_HEADER_LENGTH_DW;
+ bytes_left -= CDAT_HEADER_LENGTH_BYTES;
+
+ while (bytes_left > 0) {
+ u32 *cur_rec = data;
+ u8 type = FIELD_GET(CDAT_STRUCTURE_DW0_TYPE, cur_rec[0]);
+ u16 length = FIELD_GET(CDAT_STRUCTURE_DW0_LENGTH, cur_rec[0]);
+
+ if (type == CDAT_STRUCTURE_DW0_TYPE_DSMAS) {
+ struct cxl_dsmas *new_ary;
+ u8 flags;
+
+ new_ary = devm_krealloc(&cxlmd->dev, dsmas_ary,
+ sizeof(*dsmas_ary) * (nr_dsmas + 1),
+ GFP_KERNEL);
+ if (!new_ary) {
+ dev_err(&cxlmd->dev,
+ "Failed to allocate memory for DSMAS data\n");
+ return -ENOMEM;
+ }
+ dsmas_ary = new_ary;
+
+ flags = FIELD_GET(CDAT_DSMAS_DW1_FLAGS, cur_rec[1]);
+
+ dsmas_ary[nr_dsmas].dpa_base = CDAT_DSMAS_DPA_OFFSET(cur_rec);
+ dsmas_ary[nr_dsmas].dpa_length = CDAT_DSMAS_DPA_LEN(cur_rec);
+ dsmas_ary[nr_dsmas].non_volatile = CDAT_DSMAS_NON_VOLATILE(flags);
+
+ dev_dbg(&cxlmd->dev, "DSMAS %d: %llx:%llx %s\n",
+ nr_dsmas,
+ dsmas_ary[nr_dsmas].dpa_base,
+ dsmas_ary[nr_dsmas].dpa_base +
+ dsmas_ary[nr_dsmas].dpa_length,
+ (dsmas_ary[nr_dsmas].non_volatile ?
+ "Persistent" : "Volatile")
+ );
+
+ nr_dsmas++;
+ }
+
+ data += (length / sizeof(u32));
+ bytes_left -= length;
+ }
+
+ if (nr_dsmas == 0)
+ return -ENXIO;
+
+ dev_dbg(&cxlmd->dev, "Found %d DSMAS entries\n", nr_dsmas);
+ cxlmd->cdat.dsmas_ary = dsmas_ary;
+ cxlmd->cdat.nr_dsmas = nr_dsmas;
+
+ return 0;
+}
+
struct cxl_memdev *devm_cxl_add_memdev(struct cxl_dev_state *cxlds)
{
struct cxl_memdev *cxlmd;
@@ -407,6 +473,10 @@ struct cxl_memdev *devm_cxl_add_memdev(struct cxl_dev_state *cxlds)
if (rc)
goto err;

+ rc = parse_dsmas(cxlmd);
+ if (rc)
+ dev_warn(dev, "No DSMAS data found: %d\n", rc);
+
/*
* Activate ioctl operations, no cxl_memdev_rwsem manipulation
* needed as this is ordered with cdev_add() publishing the device.
--
2.31.1