Re: [dpdk-dev] [PATCH] vfio: remove deprecated DMA mapping functions

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 04-Nov-19 1:57 PM, Damjan Marion (damarion) wrote:
> 
> 
>> On 25 Oct 2019, at 15:02, Damjan Marion (damarion) <damarion@cisco.com 
>> <mailto:damarion@cisco.com>> wrote:
>>
>>
>>
>>> On 25 Oct 2019, at 14:23, Burakov, Anatoly <anatoly.burakov@intel.com 
>>> <mailto:anatoly.burakov@intel.com>> wrote:
>>>
>>> On 25-Oct-19 12:13 PM, Damjan Marion (damarion) wrote:
>>>>> On 25 Oct 2019, at 00:32, Thomas Monjalon <thomas@monjalon.net 
>>>>> <mailto:thomas@monjalon.net>> wrote:
>>>>>
>>>>> 24/10/2019 21:09, David Marchand:
>>>>>> On Thu, Oct 24, 2019 at 2:18 PM Anatoly Burakov
>>>>>> <anatoly.burakov@intel.com <mailto:anatoly.burakov@intel.com>> wrote:
>>>>>>>
>>>>>>> The rte_vfio_dma_map/unmap API's have been marked as deprecated in
>>>>>>> release 19.05. Remove them.
>>>>>>>
>>>>>>> Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com 
>>>>>>> <mailto:anatoly.burakov@intel.com>>
>>>>>>> ---
>>>>>>>
>>>>>>> Notes:
>>>>>>>    Although `rte_vfio_dma_map` et al. was marked as deprecated in 
>>>>>>> our documentation,
>>>>>>>    it wasn't marked as __rte_deprecated in code. Should we still 
>>>>>>> remove it?
>>>>>>
>>>>>> I can see that vpp is still using this api.
>>>>>> I would prefer we get some ack from their side.
>>>>>>
>>>>>> Shahaf?
>>>>>> Ray?
>>>>>>
>>>>>> Do you guys have contact with VPP devs?
>>>>>
>>>>> +Cc Damjan
>>>> Thanks for looping me in. If I remember correctly that was used only 
>>>> to get mlx PMDs working.
>>>> We can remove that calls but then mlx PMDs will stop working unless 
>>>> there is alternative solution.
>>>> From my perspective it is not big issue as we already have native 
>>>> rdma based mlx support, but i would expect that other people will 
>>>> complain.
>>>> Is there alternative way to tell DPDK about DMA mapping?
>>>
>>> The rte_vfio_container_dma_map(VFIO_DEFAULT_CONTAINER, ...) is the 
>>> exact equivalent of the functions being removed. Also, 
>>> rte_dev_dma_map() is supposed to be the more general DMA mapping API 
>>> that works with VFIO and with any other bus/device-specific DMA mapping.
>>>
>>> So yes, a simple search and replace for "rte_vfio_dma_(un)?map(" to 
>>> "rte_vfio_container_dma_(un)?map(VFIO_DEFAULT_CONTAINER, " should 
>>> trigger exactly the same behavior.
>>
>> Done, will be merged after it passes verify jobs…
>>
>> https://gerrit.fd.io/r/c/vpp/+/22982
> 
> I just got report that this patch breaks some tests. Is 
> it RTE_VFIO_DEFAULT_CONTAINER_FD right value to use here?
> Maybe i wrongly assumed that when you said VFIO_DEFAULT_CONTAINER, you 
> meant RTE_VFIO_DEFAULT_CONTAINER_FD…
> 
> —
> Damjan
> 
> 
Yes, i think i can see the bug. Can you rerun the failing test after 
applying the following patch?

diff --git a/lib/librte_eal/linux/eal/eal_vfio.c 
b/lib/librte_eal/linux/eal/eal_vfio.c
index d9541b1220..d7887388f9 100644
--- a/lib/librte_eal/linux/eal/eal_vfio.c
+++ b/lib/librte_eal/linux/eal/eal_vfio.c
@@ -412,6 +412,9 @@ get_vfio_cfg_by_container_fd(int container_fd)
  {
  	int i;

+	if (container_fd == RTE_VFIO_DEFAULT_CONTAINER_FD)
+		return default_vfio_cfg;
+
  	for (i = 0; i < VFIO_MAX_CONTAINERS; i++) {
  		if (vfio_cfgs[i].vfio_container_fd == container_fd)
  			return &vfio_cfgs[i];


The problem seems to be that we're looking at actual fd, whereas the 
RTE_VFIO_DEFAULT_CONTAINER_FD value is -1, which will not match anything 
in that list.

-- 
Thanks,
Anatoly