Re: [dpdk-dev] Question on mlx5 PMD txq memory registration

[Sagi Grimberg <sagi@grimberg.me>]

>> Well, this is a fair argument, but without a *complete* solution for all
>> of dpdk peripherals, it has very little merit (if at all). A badly
>> written code can just as easily crash a server by passing a mbuf to
>> a crypto device or another network device that co-exists with mlx5.
>>
>> So, while I understand the argument, I think its value is not worth the
>> hassle that mlx5_pmd needs to take to achieve it. Did this come from a
>> real requirement (from a real implementation)?
>>
> Would using VFIO (and the IOMMU) not allow us to provide an equivalent
> level of security to what is provided by the current scheme?

mlx5 does not take over the device with vfio, it simply asks the
kernel to setup resources for it and sets a mac steering rule to
direct traffic to its own rings. Also, I'm not aware of any way to
enforce iommu is enabled.

> From what I
> see on-list there are a few folks already looking into that area, and
> taking advantage of the IOMMU should improve security of all devices in
> DPDK.

I agree that this can be improved in dpdk, I was simply arguing that
mlx5 guarantees alone are not very valuable, especially considering
the work-arounds taken in mlx5 to achieve it.

mlx5 can be converted to take over the device with vfio and simply not
deal with memory registration aspects, but that is really up to mlx5
maintainers.