Messages in this thread | | | Date | Fri, 5 Jan 2018 11:11:53 -0700 | From | Keith Busch <> | Subject | Re: [PATCH 09/12] nvme-pci: Use PCI p2pmem subsystem to manage the CMB |
| |
On Thu, Jan 04, 2018 at 12:01:34PM -0700, Logan Gunthorpe wrote: > Register the CMB buffer as p2pmem and use the appropriate allocation > functions to create and destroy the IO SQ. > > If the CMB supports WDS and RDS, publish it for use as p2p memory > by other devices.
<>
> + if (qid && dev->cmb_use_sqes) { > + nvmeq->sq_cmds = pci_alloc_p2pmem(pdev, SQ_SIZE(depth));
> + nvmeq->sq_dma_addr = pci_p2pmem_virt_to_bus(pdev, > + nvmeq->sq_cmds); > + nvmeq->sq_cmds_is_io = true; > + }
This gets into some spec type trouble for creating an IO submission queue. We use the sq_dma_addr as the PRP entry to the Create I/O SQ command, which has some requirements:
"the PRP Entry shall have an offset of 0h."
So this has to be 4k aligned, but pci_alloc_p2pmem doesn't guarantee that. I doubt the spec's intention was to require such alignment for CMB SQs, but there may be controllers enforcing the rule as written.
| |