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Date: Thu, 9 Jul 2020 16:44:03 -0600
From: Alex Williamson <alex.williamson@...hat.com>
To: Diana Craciun <diana.craciun@....nxp.com>
Cc: kvm@...r.kernel.org, bharatb.linux@...il.com,
linux-kernel@...r.kernel.org, laurentiu.tudor@....com,
Bharat Bhushan <Bharat.Bhushan@....com>
Subject: Re: [PATCH v3 2/9] vfio/fsl-mc: Scan DPRC objects on vfio-fsl-mc
driver bind
On Mon, 6 Jul 2020 18:41:46 +0300
Diana Craciun <diana.craciun@....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@....com>
> Signed-off-by: Diana Craciun <diana.craciun@....nxp.com>
> ---
> drivers/vfio/fsl-mc/vfio_fsl_mc.c | 106 ++++++++++++++++++++++
> drivers/vfio/fsl-mc/vfio_fsl_mc_private.h | 1 +
> 2 files changed, 107 insertions(+)
>
> diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc.c b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> index 8b53c2a25b32..ad8d06cceb71 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 +86,69 @@ 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);
I notice the vfio-pci code that this is modeled from also doesn't check
this allocation for NULL. Maybe both should print a dev_warn on the
ultra slim chance it would fail.
> + dev_info(dev, "Setting driver override for device in dprc %s\n",
> + dev_name(&mc_cont->dev));
> + } 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);
> + }
Nit, } is over-indented, should be aligned to the previous 'else if'.
> +
> + 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) {
> + dev_err(&mc_dev->dev, "Failed to setup DPRC (error = %d)\n", 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);
> + bus_unregister_notifier(&fsl_mc_bus_type, &vdev->nb);
> + dprc_cleanup(mc_dev);
All else being equal, should these be reversed to mirror the setup?
> + }
> +
> + return ret;
> +}
> +
> static int vfio_fsl_mc_probe(struct fsl_mc_device *mc_dev)
> {
> struct iommu_group *group;
> @@ -112,9 +177,42 @@ static int vfio_fsl_mc_probe(struct fsl_mc_device *mc_dev)
> return ret;
> }
>
> + ret = vfio_fsl_mc_init_device(vdev);
> + if (ret < 0) {
> + vfio_iommu_group_put(group, dev);
> + return ret;
> + }
> +
> return ret;
> }
>
> +static int vfio_fsl_mc_device_remove(struct device *dev, void *data)
> +{
> + struct fsl_mc_device *mc_dev;
> +
> + WARN_ON(!dev);
> + mc_dev = to_fsl_mc_device(dev);
> + if (WARN_ON(!mc_dev))
> + return -ENODEV;
> +
> + kfree(mc_dev->driver_override);
> + mc_dev->driver_override = NULL;
This is out of scope, all other buses that support a driver_override
free this is the bus driver code. Why isn't it sufficient that it's
done in fsl_mc_device_remove()?
> +
> + /*
> + * The device-specific remove callback will get invoked by device_del()
> + */
> + device_del(&mc_dev->dev);
> + put_device(&mc_dev->dev);
In fact, why are we doing any of this? I think these devices were
created via dprc_scan_container(), so shouldn't there be a dprc
callback to remove them? What happens if one of them did get bound to
another driver, haven't we just deleted the device out from under them?
In vfio-pci for instance, we call pci_disable_sriov() to remove any
vfs. Thanks,
Alex
> +
> + return 0;
> +}
> +
> +static void vfio_fsl_mc_cleanup_dprc(struct fsl_mc_device *mc_dev)
> +{
> + device_for_each_child(&mc_dev->dev, NULL, vfio_fsl_mc_device_remove);
> + dprc_cleanup(mc_dev);
> +}
> +
> static int vfio_fsl_mc_remove(struct fsl_mc_device *mc_dev)
> {
> struct vfio_fsl_mc_device *vdev;
> @@ -124,6 +222,14 @@ 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))
> + vfio_fsl_mc_cleanup_dprc(vdev->mc_dev);
> +
> + 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 */
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