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

["Damjan Marion (damarion)" <damarion@cisco.com>]

> On 4 Nov 2019, at 18:27, Burakov, Anatoly <anatoly.burakov@intel.com> wrote:
> 
> 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.

That was exactly my reading, but I didn’t want to rush into conclusion. Will ask guys to test…