On Fri, Nov 5, 2021 at 12:17 AM Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote:
>
> `driver_override` allows to control which of the vDPA bus drivers
> binds to a vDPA device.
>
> If `driver_override` is not set, the previous behaviour is followed:
> devices use the first vDPA bus driver loaded (unless auto binding
> is disabled).
>
> Tested on Fedora 34 with driverctl(8):
> $ modprobe virtio-vdpa
> $ modprobe vhost-vdpa
> $ modprobe vdpa-sim-net
>
> $ vdpa dev add mgmtdev vdpasim_net name dev1
>
> # dev1 is attached to the first vDPA bus driver loaded
> $ driverctl -b vdpa list-devices
> dev1 virtio_vdpa
>
> $ driverctl -b vdpa set-override dev1 vhost_vdpa
>
> $ driverctl -b vdpa list-devices
> dev1 vhost_vdpa [*]
>
> Note: driverctl(8) integrates with udev so the binding is
> preserved.
>
> Suggested-by: Jason Wang <jasowang@xxxxxxxxxx>
> Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
> ---
> include/linux/vdpa.h | 2 ++
> drivers/vdpa/vdpa.c | 74 ++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 76 insertions(+)
>
> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> index c3011ccda430..ae34015b37b7 100644
> --- a/include/linux/vdpa.h
> +++ b/include/linux/vdpa.h
> @@ -64,6 +64,7 @@ struct vdpa_mgmt_dev;
> * struct vdpa_device - representation of a vDPA device
> * @dev: underlying device
> * @dma_dev: the actual device that is performing DMA
> + * @driver_override: driver name to force a match
This seems useless?
> * @config: the configuration ops for this device.
> * @cf_mutex: Protects get and set access to configuration layout.
> * @index: device index
> @@ -76,6 +77,7 @@ struct vdpa_mgmt_dev;
> struct vdpa_device {
> struct device dev;
> struct device *dma_dev;
> + const char *driver_override;
> const struct vdpa_config_ops *config;
> struct mutex cf_mutex; /* Protects get/set config */
> unsigned int index;
> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> index 7332a74a4b00..659231bbfee8 100644
> --- a/drivers/vdpa/vdpa.c
> +++ b/drivers/vdpa/vdpa.c
> @@ -52,8 +52,81 @@ static void vdpa_dev_remove(struct device *d)
> drv->remove(vdev);
> }
>
> +static int vdpa_dev_match(struct device *dev, struct device_driver *drv)
> +{
> + struct vdpa_device *vdev = dev_to_vdpa(dev);
> +
> + /* Check override first, and if set, only use the named driver */
> + if (vdev->driver_override)
> + return strcmp(vdev->driver_override, drv->name) == 0;
> +
> + /* Currently devices must be supported by all vDPA bus drivers */
> + return 1;
> +}
> +
> +static ssize_t driver_override_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct vdpa_device *vdev = dev_to_vdpa(dev);
> + const char *driver_override, *old;
> + char *cp;
> +
> + /* We need to keep extra room for a newline */
> + if (count >= (PAGE_SIZE - 1))
> + return -EINVAL;
> +
> + driver_override = kstrndup(buf, count, GFP_KERNEL);
> + if (!driver_override)
> + return -ENOMEM;
> +
> + cp = strchr(driver_override, '\n');
> + if (cp)
> + *cp = '\0';
> +
> + device_lock(dev);
> + old = vdev->driver_override;
> + if (strlen(driver_override)) {
> + vdev->driver_override = driver_override;
> + } else {
> + kfree(driver_override);
> + vdev->driver_override = NULL;
> + }
> + device_unlock(dev);
> +
> + kfree(old);
> +
> + return count;
> +}
> +
> +static ssize_t driver_override_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct vdpa_device *vdev = dev_to_vdpa(dev);
> + ssize_t len;
> +
> + device_lock(dev);
> + len = snprintf(buf, PAGE_SIZE, "%s\n", vdev->driver_override);
> + device_unlock(dev);
> +
> + return len;
> +}
> +static DEVICE_ATTR_RW(driver_override);
> +
> +static struct attribute *vdpa_dev_attrs[] = {
> + &dev_attr_driver_override.attr,
> + NULL,
> +};
> +
> +static const struct attribute_group vdpa_dev_group = {
> + .attrs = vdpa_dev_attrs,
> +};
> +__ATTRIBUTE_GROUPS(vdpa_dev);
> +
> static struct bus_type vdpa_bus = {
> .name = "vdpa",
> + .dev_groups = vdpa_dev_groups,
This reminds me that we probably need to document the sysfs interface
in Documentation/ABI/testing/sysfs-bus-vdpa.
But it's not the fault of this patch which look good.
Thanks
> + .match = vdpa_dev_match,
> .probe = vdpa_dev_probe,
> .remove = vdpa_dev_remove,
> };
> @@ -68,6 +141,7 @@ static void vdpa_release_dev(struct device *d)
>
> ida_simple_remove(&vdpa_index_ida, vdev->index);
> mutex_destroy(&vdev->cf_mutex);
> + kfree(vdev->driver_override);
> kfree(vdev);
> }
>
> --
> 2.31.1
>
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