This is a note to let you know that I've just added the patch titled
virtio/s390: implement virtio-ccw revision 2 correctly
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
virtio-s390-implement-virtio-ccw-revision-2-correctly.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 182f709c5cff683e6732d04c78e328de0532284f Mon Sep 17 00:00:00 2001
From: Cornelia Huck <cohuck@xxxxxxxxxx>
Date: Tue, 16 Feb 2021 12:06:45 +0100
Subject: virtio/s390: implement virtio-ccw revision 2 correctly
From: Cornelia Huck <cohuck@xxxxxxxxxx>
commit 182f709c5cff683e6732d04c78e328de0532284f upstream.
CCW_CMD_READ_STATUS was introduced with revision 2 of virtio-ccw,
and drivers should only rely on it being implemented when they
negotiated at least that revision with the device.
However, virtio_ccw_get_status() issued READ_STATUS for any
device operating at least at revision 1. If the device accepts
READ_STATUS regardless of the negotiated revision (which some
implementations like QEMU do, even though the spec currently does
not allow it), everything works as intended. While a device
rejecting the command should also be handled gracefully, we will
not be able to see any changes the device makes to the status,
such as setting NEEDS_RESET or setting the status to zero after
a completed reset.
We negotiated the revision to at most 1, as we never bumped the
maximum revision; let's do that now and properly send READ_STATUS
only if we are operating at least at revision 2.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 7d3ce5ab9430 ("virtio/s390: support READ_STATUS command for virtio-ccw")
Reviewed-by: Halil Pasic <pasic@xxxxxxxxxxxxx>
Signed-off-by: Cornelia Huck <cohuck@xxxxxxxxxx>
Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210216110645.1087321-1-cohuck@xxxxxxxxxx
Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/s390/virtio/virtio_ccw.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -103,7 +103,7 @@ struct virtio_rev_info {
};
/* the highest virtio-ccw revision we support */
-#define VIRTIO_CCW_REV_MAX 1
+#define VIRTIO_CCW_REV_MAX 2
struct virtio_ccw_vq_info {
struct virtqueue *vq;
@@ -911,7 +911,7 @@ static u8 virtio_ccw_get_status(struct v
u8 old_status = *vcdev->status;
struct ccw1 *ccw;
- if (vcdev->revision < 1)
+ if (vcdev->revision < 2)
return *vcdev->status;
ccw = kzalloc(sizeof(*ccw), GFP_DMA | GFP_KERNEL);
Patches currently in stable-queue which might be from cohuck@xxxxxxxxxx are
queue-4.19/virtio-s390-implement-virtio-ccw-revision-2-correctly.patch
