Subject: Re: [PATCH net-next 06/19] net/mlx5: Add support for mediated devices in switchdev mode

From: Jiri Pirko <[email-masked]>
Date: Fri, 8 Nov 2019 19:04:29 +0100

Fri, Nov 08, 2019 at 05:29:56PM CET, [email-masked] wrote:
>
>
>> -----Original Message-----
>> From: Jiri Pirko <[email-masked]>
>> Sent: Friday, November 8, 2019 10:23 AM
>> To: Parav Pandit <[email-masked]>
>> Cc: [email-masked]; [email-masked];
>> [email-masked]; [email-masked]; Saeed Mahameed
>> <[email-masked]>; [email-masked]; [email-masked];
>> [email-masked]; Jiri Pirko <[email-masked]>; linux-
>> [email-masked]; Vu Pham <[email-masked]>
>> Subject: Re: [PATCH net-next 06/19] net/mlx5: Add support for mediated
>> devices in switchdev mode
>> 
>> Fri, Nov 08, 2019 at 05:03:13PM CET, [email-masked] wrote:
>> >
>> >
>> >> -----Original Message-----
>> >> From: Jiri Pirko <[email-masked]>
>> >> Sent: Friday, November 8, 2019 4:33 AM
>> >> To: Parav Pandit <[email-masked]>
>> >> Cc: [email-masked]; [email-masked];
>> >> [email-masked]; [email-masked]; Saeed Mahameed
>> >> <[email-masked]>; [email-masked]; [email-masked];
>> >> [email-masked]; Jiri Pirko <[email-masked]>; linux-
>> >> [email-masked]; Vu Pham <[email-masked]>
>> >> Subject: Re: [PATCH net-next 06/19] net/mlx5: Add support for
>> >> mediated devices in switchdev mode
>> >>
>> >> Thu, Nov 07, 2019 at 05:08:21PM CET, [email-masked] wrote:
>> >> >From: Vu Pham <[email-masked]>
>> >>
>> >> [...]
>> >>
>> >>
>> >> >+static ssize_t
>> >> >+max_mdevs_show(struct kobject *kobj, struct device *dev, char *buf) {
>> >> >+	struct pci_dev *pdev = to_pci_dev(dev);
>> >> >+	struct mlx5_core_dev *coredev;
>> >> >+	struct mlx5_mdev_table *table;
>> >> >+	u16 max_sfs;
>> >> >+
>> >> >+	coredev = pci_get_drvdata(pdev);
>> >> >+	table = coredev->priv.eswitch->mdev_table;
>> >> >+	max_sfs = mlx5_core_max_sfs(coredev, &table->sf_table);
>> >> >+
>> >> >+	return sprintf(buf, "%d\n", max_sfs); } static
>> >> >+MDEV_TYPE_ATTR_RO(max_mdevs);
>> >> >+
>> >> >+static ssize_t
>> >> >+available_instances_show(struct kobject *kobj, struct device *dev,
>> >> >+char *buf) {
>> >> >+	struct pci_dev *pdev = to_pci_dev(dev);
>> >> >+	struct mlx5_core_dev *coredev;
>> >> >+	struct mlx5_mdev_table *table;
>> >> >+	u16 free_sfs;
>> >> >+
>> >> >+	coredev = pci_get_drvdata(pdev);
>> >> >+	table = coredev->priv.eswitch->mdev_table;
>> >> >+	free_sfs = mlx5_get_free_sfs(coredev, &table->sf_table);
>> >> >+	return sprintf(buf, "%d\n", free_sfs); } static
>> >> >+MDEV_TYPE_ATTR_RO(available_instances);
>> >>
>> >> These 2 arbitrary sysfs files are showing resource size/usage for the
>> >> whole eswitch/asic. That is a job for "devlink resource". Please implement
>> that.
>> >>
>> >Jiri,
>> >This series is already too long. I will implement it as follow on. It is already
>> in plan.
>> >However, available_instances file is needed regardless of devlink resource,
>> as its read by the userspace for all mdev drivers.
>> 
>> If that is the case, why isn't that implemented in mdev code rather than
>> individual drivers? I don't understand.
>>
>It should be. It isn't yet.
>It is similar to how phys_port_name preparation was done in legacy way in individual drivers and later on moved to devlink.c
>So some other time, can move this to mdev core.

Btw, Documentation/driver-api/vfio-mediated-device.rst says:
  "[<type-id>], device_api, and available_instances are mandatory attributes
   that should be provided by vendor driver."

Why don't you implement "device_api" as well?

>
> 
>> 
>> >
>> >>
>> >> >+
>> >> >+static struct attribute *mdev_dev_attrs[] = {
>> >> >+	&mdev_type_attr_max_mdevs.attr,
>> >> >+	&mdev_type_attr_available_instances.attr,
>> >> >+	NULL,
>> >> >+};
>> >> >+
>> >> >+static struct attribute_group mdev_mgmt_group = {
>> >> >+	.name  = "local",

This local name is "type-id"? Why "local?

>> >> >+	.attrs = mdev_dev_attrs,
>> >> >+};
>> >> >+
>> >> >+static struct attribute_group *mlx5_meddev_groups[] = {
>> >> >+	&mdev_mgmt_group,
>> >> >+	NULL,
>> >> >+};
>> >>
>> >> [...]