From: Halil Pasic <pasic@linux.ibm.com>
Date: Wed, 16 May 2018 19:33:42 +0200
Subject: vfio: ccw: push down unsupported IDA check
Git-commit: fb9e7880af357f0244f57a3dc4dd365091970b1a
Patch-mainline: v4.18-rc2
References: bsc#1156471 LTC#182362

There is at least one relevant guest OS that doesn't set the IDA flags in
the ORB as we would like them, but never uses any IDA. So instead of
saying -EOPNOTSUPP when observing an ORB, such that a channel program
specified by it could be a not supported one, let us say -EOPNOTSUPP only
if the channel program is a not supported one.

Of course, the real solution would be doing proper translation for all
IDA. This is possible, but given the current code not straight forward.

Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Tested-by: Jason J. Herne <jjherne@linux.ibm.com>
Message-Id: <20180516173342.15174-1-pasic@linux.ibm.com>
Reviewed-by: Dong Jia Shi <bjsdjshi@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/s390/cio/vfio_ccw_cp.c |   19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -359,6 +359,9 @@ static void cp_unpin_free(struct channel
  * This is the chain length not considering any TICs.
  * You need to do a new round for each TIC target.
  *
+ * The program is also validated for absence of not yet supported
+ * indirect data addressing scenarios.
+ *
  * Returns: the length of the ccw chain or -errno.
  */
 static int ccwchain_calc_length(u64 iova, struct channel_program *cp)
@@ -385,6 +388,14 @@ static int ccwchain_calc_length(u64 iova
 	do {
 		cnt++;
 
+		/*
+		 * As we don't want to fail direct addressing even if the
+		 * orb specified one of the unsupported formats, we defer
+		 * checking for IDAWs in unsupported formats to here.
+		 */
+		if ((!cp->orb.cmd.c64 || cp->orb.cmd.i2k) && ccw_is_idal(ccw))
+			return -EOPNOTSUPP;
+
 		if ((!ccw_is_chain(ccw)) && (!ccw_is_tic(ccw)))
 			break;
 
@@ -641,10 +652,8 @@ int cp_init(struct channel_program *cp,
 	/*
 	 * XXX:
 	 * Only support prefetch enable mode now.
-	 * Only support 64bit addressing idal.
-	 * Only support 4k IDAW.
 	 */
-	if (!orb->cmd.pfch || !orb->cmd.c64 || orb->cmd.i2k)
+	if (!orb->cmd.pfch)
 		return -EOPNOTSUPP;
 
 	INIT_LIST_HEAD(&cp->ccwchain_list);
@@ -673,6 +682,10 @@ int cp_init(struct channel_program *cp,
 	ret = ccwchain_loop_tic(chain, cp);
 	if (ret)
 		cp_unpin_free(cp);
+	/* It is safe to force: if not set but idals used
+	 * ccwchain_calc_length returns an error.
+	 */
+	cp->orb.cmd.c64 = 1;
 
 	return ret;
 }