[PATCH V12 7/9] cxl/port: Introduce cxl_cdat_valid()

ira.weiny
2022-06-28T04:16:35Z

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

The CDAT data is protected by a checksum and should be the proper
length.

Introduce cxl_cdat_valid() to validate the data. While at it check and
store the sequence number.

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

---
Changes from V8
Move code to cxl/core/pci.c

Changes from V6
Change name to cxl_cdat_valid() as this validates all the CDAT
data not just the header
Add error and debug prints

Changes from V5
New patch, split out
Update cdat_hdr_valid()
Remove revision and cs field parsing
There is no point in these
Add seq check and debug print.
---
drivers/cxl/cdat.h | 2 ++
drivers/cxl/core/pci.c | 36 ++++++++++++++++++++++++++++++++++++
2 files changed, 38 insertions(+)

diff --git a/drivers/cxl/cdat.h b/drivers/cxl/cdat.h
index c6a48ab326bf..39eb561081f2 100644
--- a/drivers/cxl/cdat.h
+++ b/drivers/cxl/cdat.h
@@ -91,10 +91,12 @@
*
* @table: cache of CDAT table
* @length: length of cached CDAT table
+ * @seq: Last read Sequence number of the CDAT table
*/
struct cxl_cdat {
void *table;
size_t length;
+ u32 seq;
};

#endif /* !__CXL_CDAT_H__ */
diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index 4bd479ec0253..6d775cc3dca1 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -532,6 +532,40 @@ static int cxl_cdat_get_length(struct device *dev,
return rc;
}

+static bool cxl_cdat_valid(struct device *dev, struct cxl_cdat *cdat)
+{
+ u32 *table = cdat->table;
+ u8 *data8 = cdat->table;
+ u32 length, seq;
+ u8 check;
+ int i;
+
+ length = FIELD_GET(CDAT_HEADER_DW0_LENGTH, table[0]);
+ if ((length < CDAT_HEADER_LENGTH_BYTES) || (length > cdat->length)) {
+ dev_err(dev, "CDAT Invalid length %u (%zu-%zu)\n", length,
+ CDAT_HEADER_LENGTH_BYTES, cdat->length);
+ return false;
+ }
+
+ for (check = 0, i = 0; i < length; i++)
+ check += data8[i];
+
+ dev_dbg(dev, "CDAT length %u CS %u\n", length, check);
+ if (check != 0) {
+ dev_err(dev, "CDAT Invalid checksum %u\n", check);
+ return false;
+ }
+
+ seq = FIELD_GET(CDAT_HEADER_DW3_SEQUENCE, table[3]);
+ /* Store the sequence for now. */
+ if (cdat->seq != seq) {
+ dev_info(dev, "CDAT seq change %x -> %x\n", cdat->seq, seq);
+ cdat->seq = seq;
+ }
+
+ return true;
+}
+
static int cxl_cdat_read_table(struct device *dev,
struct pci_doe_mb *cdat_mb,
struct cxl_cdat *cdat)
@@ -579,6 +613,8 @@ static int cxl_cdat_read_table(struct device *dev,

} while (entry_handle != CXL_DOE_TABLE_ACCESS_LAST_ENTRY);

+ if (!rc && !cxl_cdat_valid(dev, cdat))
+ return -EIO;
return rc;
}

--
2.35.3