[dpdk-dev] [RFC] ethdev: configure SR-IOV VF from host

[Thomas Monjalon <thomas@monjalon.net>]

In a virtual environment, the network controller may have to configure
some SR-IOV VF parameters for security reasons.

When the PF (host port) is drived by DPDK (OVS-DPDK case),
we face two different cases:
	- driver is bifurcated (Mellanox case),
	so the VF can be configured via the kernel.
	- driver is on top of UIO or VFIO, so DPDK API is required.

This RFC proposes to use generic DPDK API for VF configuration.
The impacted functions are (can be extended):

	- rte_eth_dev_is_valid_port
	- rte_eth_promiscuous_enable
	- rte_eth_promiscuous_disable
	- rte_eth_promiscuous_get
	- rte_eth_allmulticast_enable
	- rte_eth_allmulticast_disable
	- rte_eth_allmulticast_get
	- rte_eth_dev_set_mc_addr_list
	- rte_eth_dev_default_mac_addr_set
	- rte_eth_macaddr_get
	- rte_eth_dev_mac_addr_add
	- rte_eth_dev_mac_addr_remove
	- rte_eth_dev_vlan_filter
	- rte_eth_dev_get_mtu
	- rte_eth_dev_set_mtu

In order to target these functions to a VF (which has no port id
in the host), the higher bit of port id is reserved:

#define RTE_ETH_VF_PORT_FLAG (1 << 15)

This bit can be combined only with the port id of a representor.
The meaning is to target the VF connected with the representor port,
instead of the representor port itself.

If a function is not expected to support VF configuration,
it will return -EINVAL, i.e. there is no code change.
If an API function (listed above) can support VF configuration,
but the PMD does not support it, then -ENOTSUP must be returned.

As an example, this is the change required in rte_eth_dev_is_valid_port:

 int
 rte_eth_dev_is_valid_port(uint16_t port_id)
 {
+       uint32_t dev_flags;
+       uint16_t vf_flag;
+
+       vf_flag = port_id & RTE_ETH_VF_PORT_FLAG;
+       port_id &= RTE_ETH_VF_PORT_FLAG - 1; /* remove VF flag */
+
        if (port_id >= RTE_MAX_ETHPORTS ||
            (rte_eth_devices[port_id].state == RTE_ETH_DEV_UNUSED))
                return 0;
-       else
-               return 1;
+
+       dev_flags = rte_eth_dev_shared_data->data[port_id].dev_flags;
+       if (vf_flag != 0 && (dev_flags & RTE_ETH_DEV_REPRESENTOR) == 0)
+               return 0; /* VF flag has no meaning if not a representor */
+
+       return 1;
 }