On 2021-04-27 1:43 p.m., Jason Gunthorpe wrote: > On Thu, Apr 08, 2021 at 11:01:18AM -0600, Logan Gunthorpe wrote: >> When a PCI P2PDMA page is seen, set the IOVA length of the segment >> to zero so that it is not mapped into the IOVA. Then, in finalise_sg(), >> apply the appropriate bus address to the segment. The IOVA is not >> created if the scatterlist only consists of P2PDMA pages. > > I expect P2P to work with systems that use ATS, so we'd want to see > those systems have the IOMMU programmed with the bus address. Oh, the paragraph you quote isn't quite as clear as it could be. The bus address is only used in specific circumstances depending on how the P2PDMA core code figures the addresses should be mapped (see the documentation for (upstream_bridge_distance()). The P2PDMA code currently doesn't have any provisions for ATS (I haven't had access to any such hardware) but I'm sure it wouldn't be too hard to add. Logan _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
- Re: [PATCH 04/16] PCI/P2PDMA: Refa... John Hubbard
- Re: [PATCH 04/16] PCI/P2PDMA: ... Jason Gunthorpe
- Re: [PATCH 04/16] PCI/P2PDMA: ... John Hubbard
- [PATCH 15/16] RDMA/rw: use dma_map_sg_p2pdma() Logan Gunthorpe
- [PATCH 14/16] nvme-rdma: Ensure dma support when using p... Logan Gunthorpe
- Re: [PATCH 14/16] nvme-rdma: Ensure dma support whe... Jason Gunthorpe
- Re: [PATCH 14/16] nvme-rdma: Ensure dma support... Logan Gunthorpe
- Re: [PATCH 14/16] nvme-rdma: Ensure dma support whe... John Hubbard
- [PATCH 11/16] iommu/dma: Support PCI P2PDMA pages in dma... Logan Gunthorpe
- Re: [PATCH 11/16] iommu/dma: Support PCI P2PDMA pag... Jason Gunthorpe
- Re: [PATCH 11/16] iommu/dma: Support PCI P2PDMA... Logan Gunthorpe
- Re: [PATCH 11/16] iommu/dma: Support PCI P2PDMA pag... John Hubbard
- Re: [PATCH 11/16] iommu/dma: Support PCI P2PDMA... Logan Gunthorpe
- Re: [PATCH 11/16] iommu/dma: Support PCI P2PDMA pag... Don Dutile
- Re: [PATCH 11/16] iommu/dma: Support PCI P2PDMA... Logan Gunthorpe
- [PATCH 03/16] PCI/P2PDMA: Attempt to set map_type if it ... Logan Gunthorpe
- Re: [PATCH 03/16] PCI/P2PDMA: Attempt to set map_ty... John Hubbard
- Re: [PATCH 03/16] PCI/P2PDMA: Attempt to set ma... Logan Gunthorpe
- Re: [PATCH 03/16] PCI/P2PDMA: Attempt to se... John Hubbard
- Re: [PATCH 03/16] PCI/P2PDMA: Attempt to se... Christoph Hellwig
- Re: [PATCH 03/16] PCI/P2PDMA: Attempt t... Logan Gunthorpe