Re: [PATCH v4 02/10] vfio/fsl-mc: Scan DPRC objects on vfio-fsl-mc driver bind

[Diana Craciun OSS]

Hi Eric,

On 9/3/2020 5:06 PM, Auger Eric wrote:
> Hi Diana,
>
> On 8/26/20 11:33 AM, Diana Craciun wrote:
> > The DPRC (Data Path Resource Container) device is a bus device and has
> > child devices attached to it. When the vfio-fsl-mc driver is probed
> > the DPRC is scanned and the child devices discovered and initialized.
> >
> > Signed-off-by: Bharat Bhushan <Bharat.Bhushan@xxxxxxx>
> > Signed-off-by: Diana Craciun <diana.craciun@xxxxxxxxxxx>
> > ---
> >   drivers/vfio/fsl-mc/vfio_fsl_mc.c         | 84 +++++++++++++++++++++++
> >   drivers/vfio/fsl-mc/vfio_fsl_mc_private.h |  1 +
> >   2 files changed, 85 insertions(+)
> >
> > diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc.c b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> > index 8b53c2a25b32..85e007be3a5d 100644
> > --- a/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> > +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> > @@ -15,6 +15,8 @@
> >   
> >   #include "vfio_fsl_mc_private.h"
> >   
> > +static struct fsl_mc_driver vfio_fsl_mc_driver;
> > +
> >   static int vfio_fsl_mc_open(void *device_data)
> >   {
> >   	if (!try_module_get(THIS_MODULE))
> > @@ -84,6 +86,72 @@ static const struct vfio_device_ops vfio_fsl_mc_ops = {
> >   	.mmap		= vfio_fsl_mc_mmap,
> >   };
> >   
> > +static int vfio_fsl_mc_bus_notifier(struct notifier_block *nb,
> > +				    unsigned long action, void *data)
> > +{
> > +	struct vfio_fsl_mc_device *vdev = container_of(nb,
> > +					struct vfio_fsl_mc_device, nb);
> > +	struct device *dev = data;
> > +	struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev);
> > +	struct fsl_mc_device *mc_cont = to_fsl_mc_device(mc_dev->dev.parent);
> > +
> > +	if (action == BUS_NOTIFY_ADD_DEVICE &&
> > +	    vdev->mc_dev == mc_cont) {
> > +		mc_dev->driver_override = kasprintf(GFP_KERNEL, "%s",
> > +						    vfio_fsl_mc_ops.name);
> > +		if (!mc_dev->driver_override)
> > +			dev_warn(dev, "Setting driver override for device in dprc %s failed\n",
> > +			     dev_name(&mc_cont->dev));
> > +		dev_info(dev, "Setting driver override for device in dprc %s\n",
> > +			 dev_name(&mc_cont->dev));
> Don't you miss an else here?
> > +	} else if (action == BUS_NOTIFY_BOUND_DRIVER &&
> > +		vdev->mc_dev == mc_cont) {
> > +		struct fsl_mc_driver *mc_drv = to_fsl_mc_driver(dev->driver);
> > +
> > +		if (mc_drv && mc_drv != &vfio_fsl_mc_driver)
> > +			dev_warn(dev, "Object %s bound to driver %s while DPRC bound to vfio-fsl-mc\n",
> > +				 dev_name(dev), mc_drv->driver.name);
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int vfio_fsl_mc_init_device(struct vfio_fsl_mc_device *vdev)
> > +{
> > +	struct fsl_mc_device *mc_dev = vdev->mc_dev;
> > +	int ret;
> > +
> > +	/* Non-dprc devices share mc_io from parent */
> > +	if (!is_fsl_mc_bus_dprc(mc_dev)) {
> > +		struct fsl_mc_device *mc_cont = to_fsl_mc_device(mc_dev->dev.parent);
> > +
> > +		mc_dev->mc_io = mc_cont->mc_io;
> > +		return 0;
> > +	}
> > +
> > +	vdev->nb.notifier_call = vfio_fsl_mc_bus_notifier;
> > +	ret = bus_register_notifier(&fsl_mc_bus_type, &vdev->nb);
> > +	if (ret)
> > +		return ret;
> > +
> > +	/* open DPRC, allocate a MC portal */
> > +	ret = dprc_setup(mc_dev);
> > +	if (ret < 0) {
> if (ret) here and in other places? or are there any > returned values
> > +		dev_err(&mc_dev->dev, "Failed to setup DPRC (error = %d)\n", ret);
> nit: maybe align your error messages. Before you were using __func__,
> here you don't. Maybe don't? also you may consider using strerror(-ret)
> > +		bus_unregister_notifier(&fsl_mc_bus_type, &vdev->nb);
> > +		return ret;
> > +	}
> > +
> > +	ret = dprc_scan_container(mc_dev, false);
> > +	if (ret < 0) {
> > +		dev_err(&mc_dev->dev, "Container scanning failed: %d\n", ret);
> > +		dprc_cleanup(mc_dev);
> I see dprc_cleanup is likely to fail. Generally cleanup shouldn't.
> https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg2283433.html

Right, I will change the dprc_cleanup not to fail.


> > +		bus_unregister_notifier(&fsl_mc_bus_type, &vdev->nb);
> nit: here also you can factorize code doing goto unregister;
> shouldn't you reset vdev->nb.notifier_call to NULL as well. I see it is
> tested in other places.
> > +	}
> > +
> > +	return ret;
> > +}
> > +
> >   static int vfio_fsl_mc_probe(struct fsl_mc_device *mc_dev)
> >   {
> >   	struct iommu_group *group;
> > @@ -112,6 +180,12 @@ static int vfio_fsl_mc_probe(struct fsl_mc_device *mc_dev)
> >   		return ret;
> >   	}
> >   
> > +	ret = vfio_fsl_mc_init_device(vdev);
> > +	if (ret < 0) {
> I think you also need to call vfio_del_group_dev(&pdev->dev)
> > +		vfio_iommu_group_put(group, dev);
> > +		return ret;
> nit: goto put_group;
> > +	}
> > +
> >   	return ret;
> >   }
> >   
> > @@ -124,6 +198,16 @@ static int vfio_fsl_mc_remove(struct fsl_mc_device *mc_dev)
> >   	if (!vdev)
> >   		return -EINVAL;
> >   
> > +	if (vdev->nb.notifier_call)
> > +		bus_unregister_notifier(&fsl_mc_bus_type, &vdev->nb);
> > +
> > +	if (is_fsl_mc_bus_dprc(mc_dev)) {
> > +		dprc_remove_devices(mc_dev, NULL, 0);
> > +		dprc_cleanup(mc_dev);
> > +	}
> you may consider doing the tear down in opposite order than
> vfio_fsl_mc_init_device, ie. bus_unregister_notifier after the
> dprc_cleanup? That's also what is done in vfio_fsl_mc_init_device error
> path handling.
> > +
> > +	mc_dev->mc_io = NULL;
> > +
> >   	vfio_iommu_group_put(mc_dev->dev.iommu_group, dev);
> >   
> >   	return 0;
> > diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h b/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
> > index e79cc116f6b8..37d61eaa58c8 100644
> > --- a/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
> > +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
> > @@ -9,6 +9,7 @@
> >   
> >   struct vfio_fsl_mc_device {
> >   	struct fsl_mc_device		*mc_dev;
> > +	struct notifier_block        nb;
> >   };
> >   
> >   #endif /* VFIO_FSL_MC_PRIVATE_H */>
> Thanks
>
> Eric

Thanks,
Diana