diff mbox series

[V9,7/9] cxl/port: Introduce cxl_cdat_valid()

Message ID 20220531152632.1397976-8-ira.weiny@intel.com
State Superseded
Headers show
Series CXL: Read CDAT and DSMAS data | expand

Commit Message

Ira Weiny May 31, 2022, 3:26 p.m. UTC 
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(+)

Comments

Alison Schofield May 31, 2022, 5:21 p.m. UTC | #1 
On Tue, May 31, 2022 at 08:26:30AM -0700, Ira Weiny wrote:
> 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.
> 
Store it for ?

>  
> +static bool cxl_cdat_valid(struct device *dev, struct cxl_cdat *cdat)
> +{

snip

> +
> +	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;
> +	}
> +

Wondering when does/will this sequence number come into play?

>
Ira Weiny June 1, 2022, 10:10 p.m. UTC | #2 
On Tue, May 31, 2022 at 10:21:46AM -0700, Alison Schofield wrote:
> On Tue, May 31, 2022 at 08:26:30AM -0700, Ira Weiny wrote:
> > 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.
> > 
> Store it for ?

To see if a subsequent read shows new data.

> 
> >  
> > +static bool cxl_cdat_valid(struct device *dev, struct cxl_cdat *cdat)
> > +{
> 
> snip
> 
> > +
> > +	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;
> > +	}
> > +
> 
> Wondering when does/will this sequence number come into play?
>

Not until we start reacting to changes in CDAT.

Ira
diff mbox series

Patch

diff --git a/drivers/cxl/cdat.h b/drivers/cxl/cdat.h
index f5193a6a51fe..3d8945612511 100644
--- a/drivers/cxl/cdat.h
+++ b/drivers/cxl/cdat.h
@@ -90,10 +90,12 @@ 
  *
  * @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 4c25a7d7abfd..bb370df1cb6c 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -534,6 +534,40 @@  static int cxl_cdat_get_length(struct cxl_port *port, size_t *length)
 	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, "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, "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 cxl_port *port,
 			       struct cxl_cdat *cdat)
 {
@@ -581,6 +615,8 @@  static int cxl_cdat_read_table(struct cxl_port *port,
 
 	} while (entry_handle != 0xFFFF);
 
+	if (!rc && !cxl_cdat_valid(&port->dev, cdat))
+		return -EIO;
 	return rc;
 }