s390/cio: make fmt1 channel path descriptor optional

Not all machines / hypervisors support the chsc commands to fetch the fmt1 descriptor. When these commands fail the channel path would currently not be available to linux. Since users of these descriptors can already deal with invalid data make fetching it optional. The only data that is mandatory for us is the fmt0 channel path descriptor. Also make the return code for missing facilities in chsc_get_channel_measurement_chars consistent to other functions. Signed-off-by: Sebastian Ott <[email protected]> Reviewed-by: Cornelia Huck <[email protected]> Reviewed-by: Peter Oberparleiter <[email protected]> Signed-off-by: Martin Schwidefsky <[email protected]>
laijs · Jul 15, 2016 · 0b60137 · 0b60137
1 parent 6228c2a
commit 0b60137
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Showing 2 changed files with 8 additions and 5 deletions.
diff --git a/drivers/s390/cio/chp.c b/drivers/s390/cio/chp.c
@@ -428,11 +428,14 @@ int chp_update_desc(struct channel_path *chp)
 	if (rc)
 		return rc;
 
-	rc = chsc_determine_fmt1_channel_path_desc(chp->chpid, &chp->desc_fmt1);
-	if (rc)
-		return rc;
+	/*
+	 * Fetching the following data is optional. Not all machines or
+	 * hypervisors implement the required chsc commands.
+	 */
+	chsc_determine_fmt1_channel_path_desc(chp->chpid, &chp->desc_fmt1);
+	chsc_get_channel_measurement_chars(chp);
 
-	return chsc_get_channel_measurement_chars(chp);
+	return 0;
 }
 
 /**

diff --git a/drivers/s390/cio/chsc.c b/drivers/s390/cio/chsc.c
@@ -1020,7 +1020,7 @@ int chsc_get_channel_measurement_chars(struct channel_path *chp)
 	chp->cmg = -1;
 
 	if (!css_chsc_characteristics.scmc || !css_chsc_characteristics.secm)
-		return 0;
+		return -EINVAL;
 
 	spin_lock_irq(&chsc_page_lock);
 	memset(chsc_page, 0, PAGE_SIZE);