[PATCH v1] s390/virtio_ccw: Also suppress -EINVAL on device detach

[PATCH v1] s390/virtio_ccw: Also suppress -EINVAL on device detach

[William Bezenah]

When detaching virtio devices with multiple queues, spurious and
non-fatal error messages appear in the guest kernel log. While
virtio-net devices have multiple queues by default, this issue can
also be reproduced with other virtio device types (e.g., virtio-blk)
when configured with multiple queues:

[   33.820621] virtio_ccw 0.0.0001: Failed to deregister indicators (-22)
[   33.820628] virtio_net virtio2: Error -22 while deleting queue 0
[   33.820632] virtio_net virtio2: Error -22 while deleting queue 1
[   33.820634] virtio_net virtio2: Error -22 while deleting queue 2

Since commit 8c58a229688c ("s390/cio: Do not unregister the
subchannel based on DNV"), subchannel behavior following a device
detach has been updated and results in -EINVAL being propagated
rather than -ENODEV, originating from ccw_device_start_timeout_key()
in cio/device_ops. In the end, the virtio driver has no ability to
react to the difference between device and subchannel states here,
and during detach, both -ENODEV and -EINVAL indicate the device
cannot be used and should not be treated as errors requiring
attention. Update error handling in virtio_ccw_del_vq() and
virtio_ccw_drop_indicator() to suppress -EINVAL in addition to
-ENODEV.

Fixes: 8c58a229688c ("s390/cio: Do not unregister the subchannel based on DNV")
Signed-off-by: William Bezenah <wbezenah@linux.ibm.com>
---
 drivers/s390/virtio/virtio_ccw.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index bab6cad3fd5c..02fd8bf7e469 100644
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -429,7 +429,7 @@ static void virtio_ccw_drop_indicator(struct virtio_ccw_device *vcdev,
 			    vcdev->is_thinint ?
 			    VIRTIO_CCW_DOING_SET_IND_ADAPTER :
 			    VIRTIO_CCW_DOING_SET_IND);
-	if (ret && (ret != -ENODEV))
+	if (ret && (ret != -ENODEV) && (ret != -EINVAL))
 		dev_info(&vcdev->cdev->dev,
 			 "Failed to deregister indicators (%d)\n", ret);
 	else if (vcdev->is_thinint)
@@ -515,10 +515,10 @@ static void virtio_ccw_del_vq(struct virtqueue *vq, struct ccw1 *ccw)
 	ret = ccw_io_helper(vcdev, ccw,
 			    VIRTIO_CCW_DOING_SET_VQ | index);
 	/*
-	 * -ENODEV isn't considered an error: The device is gone anyway.
+	 * -ENODEV and -EINVAL aren't considered errors: The device is gone anyway.
 	 * This may happen on device detach.
 	 */
-	if (ret && (ret != -ENODEV))
+	if (ret && (ret != -ENODEV) && (ret != -EINVAL))
 		dev_warn(&vq->vdev->dev, "Error %d while deleting queue %d\n",
 			 ret, index);
 
-- 
2.54.0

Re: [PATCH v1] s390/virtio_ccw: Also suppress -EINVAL on device detach

[Halil Pasic]

On Fri, 12 Jun 2026 17:54:07 +0200
William Bezenah <wbezenah@linux.ibm.com> wrote:

> Since commit 8c58a229688c ("s390/cio: Do not unregister the
> subchannel based on DNV"), subchannel behavior following a device
> detach has been updated and results in -EINVAL being propagated
> rather than -ENODEV, originating from ccw_device_start_timeout_key()
> in cio/device_ops. In the end, the virtio driver has no ability to
> react to the difference between device and subchannel states here,
> and during detach, both -ENODEV and -EINVAL indicate the device
> cannot be used and should not be treated as errors requiring
> attention. Update error handling in virtio_ccw_del_vq() and
> virtio_ccw_drop_indicator() to suppress -EINVAL in addition to
> -ENODEV.

Hi William!

Are you saying that ccw_device_start() started returning -EINVAL
since 8c58a229688c ("s390/cio: Do not unregister the subchannel based on
DNV")? Or did I somehow read the paragraph wrong?

The funcition ccw_device_start is documented to return:
 * Returns:                                                                     
 *  %0, if the operation was successful;                                        
 *  -%EBUSY, if the device is busy, or status pending;                          
 *  -%EACCES, if no path specified in @lpm is operational;                      
 *  -%ENODEV, if the device is not operational. 
and the commit message does not say a thing about introducing -EINVAL to
the mix.

Regards,
Halil 

Re: [PATCH v1] s390/virtio_ccw: Also suppress -EINVAL on device detach

[Cornelia Huck]

On Mon, Jun 15 2026, Halil Pasic <pasic@linux.ibm.com> wrote:

> On Fri, 12 Jun 2026 17:54:07 +0200
> William Bezenah <wbezenah@linux.ibm.com> wrote:
>
>> Since commit 8c58a229688c ("s390/cio: Do not unregister the
>> subchannel based on DNV"), subchannel behavior following a device
>> detach has been updated and results in -EINVAL being propagated
>> rather than -ENODEV, originating from ccw_device_start_timeout_key()
>> in cio/device_ops. In the end, the virtio driver has no ability to
>> react to the difference between device and subchannel states here,
>> and during detach, both -ENODEV and -EINVAL indicate the device
>> cannot be used and should not be treated as errors requiring
>> attention. Update error handling in virtio_ccw_del_vq() and
>> virtio_ccw_drop_indicator() to suppress -EINVAL in addition to
>> -ENODEV.
>
> Hi William!
>
> Are you saying that ccw_device_start() started returning -EINVAL
> since 8c58a229688c ("s390/cio: Do not unregister the subchannel based on
> DNV")? Or did I somehow read the paragraph wrong?
>
> The funcition ccw_device_start is documented to return:
>  * Returns:                                                                     
>  *  %0, if the operation was successful;                                        
>  *  -%EBUSY, if the device is busy, or status pending;                          
>  *  -%EACCES, if no path specified in @lpm is operational;                      
>  *  -%ENODEV, if the device is not operational. 
> and the commit message does not say a thing about introducing -EINVAL to
> the mix.

The function may return -EINVAL for non-enabled subchannels
(i.e. pmcw.ena == 0), maybe we get an all-zeroes schib with dnv == 0?
I'd expect it not to be enabled in that case anyway.

Re: [PATCH v1] s390/virtio_ccw: Also suppress -EINVAL on device detach

[William Bezenah]

On 6/15/2026 10:58 AM, Cornelia Huck wrote:
> On Mon, Jun 15 2026, Halil Pasic <pasic@linux.ibm.com> wrote:
>
>> On Fri, 12 Jun 2026 17:54:07 +0200
>> William Bezenah <wbezenah@linux.ibm.com> wrote:
>>
>>> Since commit 8c58a229688c ("s390/cio: Do not unregister the
>>> subchannel based on DNV"), subchannel behavior following a device
>>> detach has been updated and results in -EINVAL being propagated
>>> rather than -ENODEV, originating from ccw_device_start_timeout_key()
>>> in cio/device_ops. In the end, the virtio driver has no ability to
>>> react to the difference between device and subchannel states here,
>>> and during detach, both -ENODEV and -EINVAL indicate the device
>>> cannot be used and should not be treated as errors requiring
>>> attention. Update error handling in virtio_ccw_del_vq() and
>>> virtio_ccw_drop_indicator() to suppress -EINVAL in addition to
>>> -ENODEV.
>> Hi William!
>>
>> Are you saying that ccw_device_start() started returning -EINVAL
>> since 8c58a229688c ("s390/cio: Do not unregister the subchannel based on
>> DNV")? Or did I somehow read the paragraph wrong?
>>
>> The funcition ccw_device_start is documented to return:
>>  * Returns:                                                                     
>>  *  %0, if the operation was successful;                                        
>>  *  -%EBUSY, if the device is busy, or status pending;                          
>>  *  -%EACCES, if no path specified in @lpm is operational;                      
>>  *  -%ENODEV, if the device is not operational. 
>> and the commit message does not say a thing about introducing -EINVAL to
>> the mix.
> The function may return -EINVAL for non-enabled subchannels
> (i.e. pmcw.ena == 0), maybe we get an all-zeroes schib with dnv == 0?
> I'd expect it not to be enabled in that case anyway.

Yep, that's at least how I've come to understand what changed. The
function ccw_device_start_timeout_key() has always returned -EINVAL
for non-enabled subchannels (pmcw.ena == 0), though it's not
documented in the header.

What changed with commit 8c58a229688c is that cio_update_schib() now
updates the schib even when DNV=0, rather than returning early as it
did previously. Somehow this update results in pmcw.ena == 0 in
ccw_device_start_timeout_key(). Previously, it saw pmcw.ena == 1 and
moved to the condition (cdev->private->state == DEV_STATE_NOT_OPER)
where it returned -ENODEV.

So the commit didn't introduce -EINVAL as a new return value, rather,
it changed the subchannel lifecycle such that existing paths now
propagate -EINVAL rather than -ENODEV during the device detach
scenario.