On Mon, Oct 07 2024, Halil Pasic <[email protected]> wrote: > At least since commit 334304ac2bac ("dma-mapping: don't return errors > from dma_set_max_seg_size") setting up device.dma_parms is basically > mandated by the DMA API. As of now Channel (CCW) I/O in general does not > utilize the DMA API, except for virtio. For virtio-ccw however the > common virtio DMA infrastructure is such that most of the DMA stuff > hinges on the virtio parent device, which is a CCW device. > > So lets set up the dma_parms pointer for the CCW parent device and hope > for the best! > > Signed-off-by: Halil Pasic <[email protected]> > Fixes: 334304ac2bac ("dma-mapping: don't return errors from > dma_set_max_seg_size") > Reported-by: "Marc Hartmayer" <[email protected]> > Closes: https://bugzilla.linux.ibm.com/show_bug.cgi?id=209131 > Reviewed-by: Eric Farman <[email protected]> > --- > > In the long run it may make sense to move dma_parms into struct > ccw_device, since layering-wise it is much cleaner. I decided > to put it in virtio_ccw_device because currently it is only used for > virtio.
Yes, ccw_device would make more sense as a resting place; no idea what other devices (dasd, QDIO based, ...) would do with it ATM -- I agree that if adding it to virtio_ccw_device get things going again, we should do that and consider the possible generic case later. Reviewed-by: Cornelia Huck <[email protected]> [I assume this one can be picked up together with other s390 patches?] > > --- > drivers/s390/virtio/virtio_ccw.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/s390/virtio/virtio_ccw.c > b/drivers/s390/virtio/virtio_ccw.c > index 62eca9419ad7..21fa7ac849e5 100644 > --- a/drivers/s390/virtio/virtio_ccw.c > +++ b/drivers/s390/virtio/virtio_ccw.c > @@ -58,6 +58,8 @@ struct virtio_ccw_device { > struct virtio_device vdev; > __u8 config[VIRTIO_CCW_CONFIG_SIZE]; > struct ccw_device *cdev; > + /* we make cdev->dev.dma_parms point to this */ > + struct device_dma_parameters dma_parms; > __u32 curr_io; > int err; > unsigned int revision; /* Transport revision */ > @@ -1303,6 +1305,7 @@ static int virtio_ccw_offline(struct ccw_device *cdev) > unregister_virtio_device(&vcdev->vdev); > spin_lock_irqsave(get_ccwdev_lock(cdev), flags); > dev_set_drvdata(&cdev->dev, NULL); > + cdev->dev.dma_parms = NULL; > spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags); > return 0; > } > @@ -1366,6 +1369,7 @@ static int virtio_ccw_online(struct ccw_device *cdev) > } > vcdev->vdev.dev.parent = &cdev->dev; > vcdev->cdev = cdev; > + cdev->dev.dma_parms = &vcdev->dma_parms; > vcdev->dma_area = ccw_device_dma_zalloc(vcdev->cdev, > sizeof(*vcdev->dma_area), > &vcdev->dma_area_addr); > > base-commit: 87d6aab2389e5ce0197d8257d5f8ee965a67c4cd
