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SubjectRe: [PATCH v5 02/10] vfio/fsl-mc: Scan DPRC objects on vfio-fsl-mc driver bind
On Tue, 29 Sep 2020 12:03:31 +0300
Diana Craciun <diana.craciun@oss.nxp.com> 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@nxp.com>
> Signed-off-by: Diana Craciun <diana.craciun@oss.nxp.com>
> ---
> drivers/vfio/fsl-mc/vfio_fsl_mc.c | 90 +++++++++++++++++++++++
> drivers/vfio/fsl-mc/vfio_fsl_mc_private.h | 1 +
> 2 files changed, 91 insertions(+)
>
> diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc.c b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> index a7a483a1e90b..ba44d6d01cc9 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 +86,79 @@ 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, "VFIO_FSL_MC: Setting driver override for device in dprc %s failed\n",
> + dev_name(&mc_cont->dev));
> + else
> + dev_info(dev, "VFIO_FSL_MC: Setting driver override for device in dprc %s\n",
> + dev_name(&mc_cont->dev));

Nit, some whitespace inconsistencies on the second line of each of
these. I can fixup on commit if we don't find anything else worth a
respin.

> + } 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, "VFIO_FSL_MC: 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) {
> + dev_err(&mc_dev->dev, "VFIO_FSL_MC: Failed to setup DPRC (%d)\n", ret);
> + goto out_nc_unreg;
> + }
> +
> + ret = dprc_scan_container(mc_dev, false);
> + if (ret) {
> + dev_err(&mc_dev->dev, "VFIO_FSL_MC: Container scanning failed (%d)\n", ret);
> + goto out_dprc_cleanup;
> + }

If I understand this correctly, we've setup the bus notifier to write
the driver override as each sub-devices appear on the bus from this
scan. When non-dprc devices are removed below, it appears we remove all
their sub-devices. Is there a chance here that an error from the scan
leaves residual sub-devices, ie. should we proceed the below
dprc_cleanup() with a call to dprc_remove_devices() to be certain none
remain? Thanks,

Alex


> +
> + return 0;
> +
> +out_dprc_cleanup:
> + dprc_cleanup(mc_dev);
> +out_nc_unreg:
> + bus_unregister_notifier(&fsl_mc_bus_type, &vdev->nb);
> + vdev->nb.notifier_call = NULL;
> +
> + return ret;
> +}
> +
> static int vfio_fsl_mc_probe(struct fsl_mc_device *mc_dev)
> {
> struct iommu_group *group;
> @@ -110,8 +185,15 @@ static int vfio_fsl_mc_probe(struct fsl_mc_device *mc_dev)
> dev_err(dev, "VFIO_FSL_MC: Failed to add to vfio group\n");
> goto out_group_put;
> }
> +
> + ret = vfio_fsl_mc_init_device(vdev);
> + if (ret)
> + goto out_group_dev;
> +
> return 0;
>
> +out_group_dev:
> + vfio_del_group_dev(dev);
> out_group_put:
> vfio_iommu_group_put(group, dev);
> return ret;
> @@ -126,6 +208,14 @@ static int vfio_fsl_mc_remove(struct fsl_mc_device *mc_dev)
> if (!vdev)
> return -EINVAL;
>
> + if (is_fsl_mc_bus_dprc(mc_dev)) {
> + dprc_remove_devices(mc_dev, NULL, 0);
> + dprc_cleanup(mc_dev);
> + }
> +
> + if (vdev->nb.notifier_call)
> + bus_unregister_notifier(&fsl_mc_bus_type, &vdev->nb);
> +
> 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 */

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