Hi Thomas, Bruce, <snip>
> Subject: Re: [dpdk-dev] [RFC PATCH v2 3/5] librte_ether: add API's for VF > management > > 2016-09-23 17:02, Iremonger, Bernard: > > From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com] > > > 2016-09-23 09:53, Richardson, Bruce: > > > > From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com] > > > > > 2016-09-23 10:20, Bruce Richardson: > > > > > > On Thu, Sep 22, 2016 at 07:04:37PM +0200, Thomas Monjalon wrote: > > > > > > > 2016-09-15 16:46, Iremonger, Bernard: > > > > > > > > > > > Do we really need to expose VF specific functions here? > > > > > > > > > > > It can be generic(PF/VF) function indexed only > > > > > > > > > > > through > > > > > port_id. > > > > > > > > > > > (example: as rte_eth_dev_set_vlan_anti_spoof(uint8_t > > > > > > > > > > > port_id, uint8_t on)) For instance, In Thunderx PMD, > > > > > > > > > > > We are not exposing a separate port_id for PF. We > > > > > > > > > > > only enumerate 0..N VFs as 0..N ethdev port_id > > > > > > > > > > > > > > > > > > > > Our intention with this patch is to control the VF from the > > > > > > > > > > PF. > > > > > > > > > > > > > > > > > > > > The following librte_ether functions already work in a > > > > > > > > > > similar > > > > > way: > > > > > > > > > > > > > > > > > > > > rte_eth_dev_set_vf_rxmode(uint8_t port_id, uint16_t > > > > > > > > > > vf, uint16_t rx_mode, uint8_t on) > > > > > > > > > > > > > > > > > > > > rte_eth_dev_set_vf_rx(uint8_t port_id, uint16_t vf, > > > > > > > > > > uint8_t > > > > > > > > > > on) > > > > > > > > > > > > > > > > > > > > rte_eth_dev_set_vf_tx(uint8_t port_id, uint16_t vf, > > > > > > > > > > uint8_t > > > > > > > > > > on) > > > > > > > > > > > > > > > > > > > > int rte_eth_set_vf_rate_limit(uint8_t port_id, > > > > > > > > > > uint16_t vf, uint16_t tx_rate, uint64_t q_msk) > > > > > > > > > > > > > > > > > > I have a bad feeling with these functions dedicated to VF from > PF. > > > > > > > > > Are we sure there is no other way? > > > > > > > > > I mean we just need to know the VF with a port ID. > > > > > > > > > > > > > > > > When the VF is used in a VM the port ID of the VF is not > > > > > > > > visible to > > > > > the PF. > > > > > > > > I don't think there is another way to do this. > > > > > > > > > > > > > > I don't understand why we could not assign a port id to the > > > > > > > VF from the host instead of having the couple PF port id / VF id. > > > > > > > Can we enumerate all the VFs associated to a PF? > > > > > > > Then can we allocate them a port id in the array rte_eth_devices? > > > > > > > > > > > > Hi Thomas, > > > > > > > > > > > > The VF is not a port visible to DPDK, though, so it shouldn't > > > > > > have a port id IMHO. DPDK can't actually do anything with it. > > > > > > > > > > You say the contrary below. > > > > > > > > Well, yes and no. The driver can manipulate things for the VF, but > > > > DPDK > > > doesn't actually have a device that corresponds to the VF. There are > > > no PCI bar mappings for it, DPDK can't do RX and TX with it etc.? > > > > > > Very good point. > > > There are only few ethdev functions which are supported by every > > > drivers, like Rx/Tx and would not be available for VF from PF interface. > > > > > > > > > The PCI device for the VF is likely passed through to a > > > > > > different VM and being used there. Unfortunately, the VF still > > > > > > needs certain things done for it by the PF, so if the PF is > > > > > > under DPDK control, it needs to provide the functionality to assist > the VF. > > > > > > > > > > Why not have a VF_from_PF driver which does the mailbox things? > > > > > So you can manage the VF from the PF with a simple port id. > > > > > It really seems to be the cleanest design to me. > > > > > > > > While I see your point, and it could work, I just want to be sure > > > > that we are > > > ok with the results of that. Suppose we do create ethdevs for the > > > VFs controlled by the PF. Does the new VF get counted in the > > > rte_eth_dev_count() value (I assume yes)? How are apps meant to use > > > the port? Do they have to put in a special case when iterating > > > through all the port ids to check that it's not a pseudo port that > > > can't do anything. None of the standard ethdev calls from an app > > > will work on it, you can't configure nb rx/tx queues on it, you can't > > > start or > stop it, you can't do rx or tx on it, etc, etc. > > > > > > Yes these devices would be special because their supported API would > > > be quite different. I was thinking that in the future you could add > > > most of the configuration functions through the VF mailbox. > > > But the Intel mailbox currently support only some special > > > configurations which are not supported by other devices even its own > > > VF device (except setting MAC address). > > > And when I read "set drop enable bit in the VF split rx control > > > register", it becomes clear it is really specific and has nothing to > > > do in the generic ethdev API. > > > That's why it is a NACK. > > > > > > When we want to use these very specific features we are aware of the > > > underlying device and driver. So we can directly include a header > > > from the driver. I suggest to retrieve a handler for the device > > > which is not a port id and will allow to call ixgbe functions directly. > > > It could be achieved by adding an ethdev function like discussed here: > > > http://dpdk.org/ml/archives/dev/2016-September/047392.html > > > > > > > I have been reading the net/vhost mail thread above. The following quote > is from this thread. > > > > "It means I would be in favor of introducing API in drivers for very > > specific > features." > > > > At present all the PMD functions are accessed through the eth_dev_ops > structure, there are no PMD API's. > > > > Is your proposal to add API(s) to the DPDK ixgbe PMD (similar to a driver > ioctl API) which can be accessed through a generic API in the ethdev? > > Not exactly. I'm thinking about a PMD specific API. > The only ethdev API you need would be a function to retrieve a handler (an > opaque pointer on the device struct) from the port id. > Then you can include rte_ixgbe.h and directly call the specific ixgbe > function, > passing the device handler. > How does it sound? I have been prototyping this proposed solution, it appears to work. I have added the following function: int rte_eth_dev_get_pmd_handle(uint8_t port_id, void** pmd_handle); The pmd_handle is a pointer to a dev_ops structure containing driver specific functions. Using the pmd_handle the driver specific functions can be called (without having them in struct eth_dev_ops) Has this proposal been superseded by the discussion on the following patch? [PATCH] net/vhost: Add function to retreive the 'vid' for a given port id Regards, Bernard.
