FAILED: patch "[PATCH] s390/vfio_ccw: Calculate idal length based on idaw type" failed to apply to 6.6-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 4f6fdc6e1a7fbfa36b945af33c65a417948feac0
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026082058-slush-preface-49a0@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4f6fdc6e1a7fbfa36b945af33c65a417948feac0 Mon Sep 17 00:00:00 2001
From: Eric Farman <farman@linux.ibm.com>
Date: Tue, 28 Jul 2026 05:30:17 +0200
Subject: [PATCH] s390/vfio_ccw: Calculate idal length based on idaw type

Sashiko pointed out that get_guest_idal() unconditionally calculates
the length of the IDAL presuming everything is a Format-2 IDAW.

The output of vfio-ccw is always Format-2, but the input can be either
Format-1 (31-bit addresses) or Format-2 (64-bit addresses). As a result,
the size of the guest IDAL may be incorrect and should be trimmed down.

Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Link: https://lore.kernel.org/r/20260720203400.7328E1F000E9@smtp.kernel.org/
Fixes: 1b676fe3d9d3 ("vfio/ccw: handle a guest Format-1 IDAL")
Cc: stable@vger.kernel.org
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>

diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c
index 6275794751cb..5ef082b8289a 100644
--- a/drivers/s390/cio/vfio_ccw_cp.c
+++ b/drivers/s390/cio/vfio_ccw_cp.c
@@ -233,6 +233,7 @@ static void convert_ccw0_to_ccw1(struct ccw1 *source, unsigned long len)
 }
 
 #define idal_is_2k(_cp) (!(_cp)->orb.cmd.c64 || (_cp)->orb.cmd.i2k)
+#define get_idaw_size(_cp) ((_cp)->orb.cmd.c64 ? sizeof(u64) : sizeof(u32))
 
 /*
  * Helpers to operate ccwchain.
@@ -524,7 +525,7 @@ static dma64_t *get_guest_idal(struct ccw1 *ccw, struct channel_program *cp, int
 	dma64_t *idaws;
 	dma32_t *idaws_f1;
 	u64 first_idaw;
-	int idal_len = idaw_nr * sizeof(*idaws);
+	int idal_len = idaw_nr * get_idaw_size(cp);
 	int idaw_size = idal_is_2k(cp) ? PAGE_SIZE / 2 : PAGE_SIZE;
 	int idaw_mask = ~(idaw_size - 1);
 	int i, ret;
@@ -593,7 +594,7 @@ static int ccw_count_idaws(struct ccw1 *ccw,
 	struct vfio_device *vdev =
 		&container_of(cp, struct vfio_ccw_private, cp)->vdev;
 	u64 iova;
-	int size = cp->orb.cmd.c64 ? sizeof(u64) : sizeof(u32);
+	int size = get_idaw_size(cp);
 	int ret;
 	int bytes = 1;