[dpdk-dev] [PATCH v2 1/2] eal/pci: introduce a PCI driver flag

[Ferruh Yigit]

On 6/8/2017 6:15 PM, Jerin Jacob wrote:
> -----Original Message-----
>> Date: Thu, 8 Jun 2017 15:40:33 +0100
>> From: Ferruh Yigit <ferruh.yigit at intel.com>
>> To: Jerin Jacob <jerin.jacob at caviumnetworks.com>, dev at dpdk.org
>> CC: thomas at monjalon.net
>> Subject: Re: [dpdk-dev] [PATCH v2 1/2] eal/pci: introduce a PCI driver flag
>> User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101
>>  Thunderbird/52.1.1
>>
>> On 6/8/2017 12:44 PM, Jerin Jacob wrote:
>>> Some ethdev devices like nicvf thunderx PMD need special treatment for
>>> Secondary queue set(SQS) PCIe VF devices, where, it expects to not unmap
>>> or free the memory without registering the ethdev subsystem.
>>>
>>> Introducing a new RTE_PCI_DRV_KEEP_MAPPED_RES
>>> PCI driver flag to request PCI subsystem to not unmap the mapped PCI
>>> resources(PCI BAR address) if unsupported device detected.
>>>
>>> Signed-off-by: Jerin Jacob <jerin.jacob at caviumnetworks.com>
>>
>> <...>
>>
>>> @@ -235,6 +240,7 @@ rte_pci_probe_one_driver(struct rte_pci_driver *dr,
>>>  static int
>>>  rte_pci_detach_dev(struct rte_pci_device *dev)
>>>  {
>>> +	int ret = 0;
>>>  	struct rte_pci_addr *loc;
>>>  	struct rte_pci_driver *dr;
>>>  
>>> @@ -251,13 +257,18 @@ rte_pci_detach_dev(struct rte_pci_device *dev)
>>>  	RTE_LOG(DEBUG, EAL, "  remove driver: %x:%x %s\n", dev->id.vendor_id,
>>>  			dev->id.device_id, dr->driver.name);
>>>  
>>> -	if (dr->remove && (dr->remove(dev) < 0))
>>> -		return -1;	/* negative value is an error */
>>> +	if (dr->remove) {
>>> +		ret = dr->remove(dev);
>>> +		if (ret < 0)
>>> +			return -1; /* negative value is an error */
>>> +	}
>>>  
>>>  	/* clear driver structure */
>>>  	dev->driver = NULL;
>>>  
>>> -	if (dr->drv_flags & RTE_PCI_DRV_NEED_MAPPING)
>>> +	if ((dr->drv_flags & RTE_PCI_DRV_NEED_MAPPING) &&
>>> +	/* Don't unmap if dev is unsupported and it needs mapped resources */
>>> +		!(ret > 0 && (dr->drv_flags & RTE_PCI_DRV_KEEP_MAPPED_RES)))
>>
>> Why it is required to keep mapping during detach?
> 
> To keep symmetrical with other(on probe) unmap change. This will
> activated only when PMD returns the positive number on remove() so PMD
> has control over it. The existing use case, We cannot just detach a single
> VF(one SQS VF is _not_ one ethdev port i.e one ethdev port consists of
> multiple VFs) so we need control on when to unmap those BARs.

For generic eal, there is an explicit request to detach the device, I am
not sure about returning success but not releasing the resources based
on PMD flag. How this will work with hotplug?


And specific to your case, -thanks for clarification, since no eth_dev
created for SQS VF, rte_eth_dev_pci_generic_remove() won't be useful but
assuming you have implemented your remove(), can it be possible to
detect SQS VF and act accordingly, or just return error perhaps if you
cannot detach that VF?

> 
>>
>>>  		/* unmap resources for devices that use igb_uio */
>>>  		rte_pci_unmap_device(dev);
>>>  
>>
>> <...>
>>