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From: Cornelia Huck <cohuck@redhat.com>
To: Heiko Carstens <heiko.carstens@de.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Farhan Ali <alifm@linux.ibm.com>,
	Eric Farman <farman@linux.ibm.com>,
	Halil Pasic <pasic@linux.ibm.com>,
	linux-s390@vger.kernel.org, kvm@vger.kernel.org,
	Cornelia Huck <cohuck@redhat.com>
Subject: [PULL 1/5] vfio-ccw: Fix misleading comment when setting orb.cmd.c64
Date: Tue, 16 Jul 2019 12:09:04 +0200
Message-ID: <20190716100908.3460-2-cohuck@redhat.com> (raw)
In-Reply-To: <20190716100908.3460-1-cohuck@redhat.com>

From: Farhan Ali <alifm@linux.ibm.com>

The comment is misleading because it tells us that
we should set orb.cmd.c64 before calling ccwchain_calc_length,
otherwise the function ccwchain_calc_length would return an
error. This is not completely accurate.

We want to allow an orb without cmd.c64, and this is fine
as long as the channel program does not use IDALs. But we do
want to reject any channel program that uses IDALs and does
not set the flag, which is what we do in ccwchain_calc_length.

After we have done the ccw processing, we need to set cmd.c64,
as we use IDALs for all translated channel programs.

Also for better code readability let's move the setting of
cmd.c64 within the non error path.

Fixes: fb9e7880af35 ("vfio: ccw: push down unsupported IDA check")
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <f68636106aef0faeb6ce9712584d102d1b315ff8.1562854091.git.alifm@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
 drivers/s390/cio/vfio_ccw_cp.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index 1d4c893ead23..46967c664c0f 100644
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -645,14 +645,15 @@ int cp_init(struct channel_program *cp, struct device *mdev, union orb *orb)
 	if (ret)
-	/* It is safe to force: if not set but idals used
-	 * ccwchain_calc_length returns an error.
-	 */
-	cp->orb.cmd.c64 = 1;
-	if (!ret)
+	if (!ret) {
 		cp->initialized = true;
+		/* It is safe to force: if it was not set but idals used
+		 * ccwchain_calc_length would have returned an error.
+		 */
+		cp->orb.cmd.c64 = 1;
+	}
 	return ret;

  reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-16 10:09 [PULL 0/5] vfio-ccw fixes for 5.3 Cornelia Huck
2019-07-16 10:09 ` Cornelia Huck [this message]
2019-07-16 10:09 ` [PULL 2/5] vfio-ccw: Fix memory leak and don't call cp_free in cp_init Cornelia Huck
2019-07-16 10:09 ` [PULL 3/5] vfio-ccw: Set pa_nr to 0 if memory allocation fails for pa_iova_pfn Cornelia Huck
2019-07-16 10:09 ` [PULL 4/5] vfio-ccw: Don't call cp_free if we are processing a channel program Cornelia Huck
2019-07-16 10:09 ` [PULL 5/5] vfio-ccw: Update documentation for csch/hsch Cornelia Huck
2019-07-17  9:43 ` [PULL 0/5] vfio-ccw fixes for 5.3 Cornelia Huck

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