Re: [PATCH v3 00/20] Userspace P2PDMA with O_DIRECT NVMe devices

[Logan Gunthorpe]

On 2021-09-28 2:02 p.m., Jason Gunthorpe wrote:
> On Thu, Sep 16, 2021 at 05:40:40PM -0600, Logan Gunthorpe wrote:
>> Hi,
>>
>> This patchset continues my work to add userspace P2PDMA access using
>> O_DIRECT NVMe devices. My last posting[1] just included the first 13
>> patches in this series, but the early P2PDMA cleanup and map_sg error
>> changes from that series have been merged into v5.15-rc1. To address
>> concerns that that series did not add any new functionality, I've added
>> back the userspcae functionality from the original RFC[2] (but improved
>> based on the original feedback).
> 
> I really think this is the best series yet, it really looks nice
> overall. I know the sg flag was a bit of a debate at the start, but it
> serves an undeniable purpose and the resulting standard DMA APIs 'just
> working' is really clean.

Actually, so far, nobody has said anything negative about using the SG flag.

> There is more possible here, we could also pass the new GUP flag in the
> ib_umem code..

Yes, that would be very useful.

> After this gets merged I would make a series to split out the CMD
> genalloc related stuff and try and probably get something like VFIO to
> export this kind of memory as well, then it would have pretty nice
> coverage.

Yup!

Thanks for the review. Anything I didn't respond to I've either made
changes for, or am still working on and will be addressed for subsequent
postings.

Logan