Messages in this thread | | | From | Logan Gunthorpe <> | Date | Tue, 4 Apr 2017 11:21:58 -0600 | Subject | Re: [RFC 6/8] nvmet: Be careful about using iomem accesses when dealing with p2pmem |
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On 04/04/17 04:59 AM, Sagi Grimberg wrote: > We can never ever get here from an IO command, and that is a good thing > because it would have been broken if we did, regardless of what copy > method we use...
Yes, I changed this mostly for admin commands. I did notice connect commands do end up reading from the p2mem and this patchset correctly switches it to iomemcpy. However, based on Cristoph's comment, I hope to make it more general such that iomem is hidden within sgls and any access will either be correct or create a warning.
On 04/04/17 09:46 AM, Jason Gunthorpe wrote: > Transactions might not complete at the NVMe device before the CPU > processes the RDMA completion, however due to the PCI-E ordering rules > new TLPs directed to the NVMe will complete after the RMDA TLPs and > thus observe the new data. (eg order preserving) > > It would be very hard to use P2P if fabric ordering is not preserved..
Yes, my understanding is the same, the PCI-E ordering rules save us here.
Thanks,
Logan
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