On Wed, May 31, 2017 at 12:02:56PM +0000, Diana Madalina Craciun wrote: > On 05/25/2017 01:12 AM, Michael S. Tsirkin wrote: > > On Tue, May 23, 2017 at 02:12:43PM +0300, Diana Craciun wrote: > >> The NXP DPAA2 is a hardware architecture designed for high-speeed network > >> packet processing. The DPAA2 hardware components are managed by a hardware > >> component called the Management Complex (or MC) which provides an > >> object-base abstraction for software drivers to use the DPAA2 hardware. > >> For more details you can see: > >> https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.kernel.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Ftorvalds%2Flinux.git%2Ftree%2Fdrivers%2Fstaging%2Ffsl-mc%2FREADME.txt%3Fh%3Dv4.10&data=01%7C01%7Cdiana.craciun%40nxp.com%7Cce2cc4d066944ce2759308d4a2f1f3f8%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0&sdata=CJAiTF6Qnq4gklSqon7xcRby0O1HQvytTUSdPwaHuSE%3D&reserved=0 > >> > >> The interrupts generated by the DPAA2 hardware components are MSIs. We > >> will add > >> support for direct assigning these DPAA2 components/objects to a virtual > >> machine. However, this will add the need to expand the MSI usage in QEMU. > >> > >> Currently the MSIs in QEMU are pretty much tied to PCI. For ARM the > >> GIC ITS is using a device ID for interrupt translation. Currently, for > >> PCI, the requester ID is used as device ID. This will not work when > >> we add another entity that needs also a device ID which is supposed to > >> be unique across the system. > >> > >> My proposal is to add a static allocation in the virt machine. I considered > >> that this allocation is specific to each machine/platform. Currently only > >> virt machine has it, but other implementations may use the same mechanism > >> as well. > >> So, I used a static allocation with this formula: > >> > >> DeviceID = zero_extend( RequesterID[15:0] ) + 0x10000 * Constant > >> > >> This formula was taken from SBSA spec (Appendix I: DeviceID generation and > >> ITS groups). In case of QEMU the constant will be different for each > >> entity. > >> In this way a unique DeviceID will be generated and the device ID will be > >> derived from a requesterID (in case of PCI) or other means in case of other > >> entities. > >> > >> The implementation is generic as there might be in the future other > >> non-pci devices > >> that are using MSIs or IOMMU. Any architecture can use it, though currently > >> only the ARM architecture is using the function that retrieves the stream > >> ID. I > >> did not change all the replacements of the pci_requester_id (with > >> pci_stream_id) > >> in the code (although if the constant is 0, the stream_id is equal with > >> requester_id). > >> The other architectures (e.g. intel iommu code) assume that the ID is the > >> requester ID. > >> > >> Tested on NXP LS2080 platform. > >> > >> History: > > I am confused. I get it that non-PCI things want something else > > in their requester ID, but why require it for PCI devices? > > How about using Constant == 0 for PCI? This way you do > > not need to touch PCI at all as DeviceID == RequesterID ... > > It is not that other devices need something else in the requester ID, > but more about finding a way to provide an unique ID across the system > (more precisely it should be unique for all devices connected to the > same IOMMU/ITS). The DT already offers support to describe the > translation between stream IDs/device IDs to requester ID for PCI > devices (iommu-map for IOMMU ([1]) and msi-map for MSIs ([2]). It will > not change the way the requester ID is used in PCI in general, but only > the places that need a unique ID (which are the MSIs and IOMMU). > > If we are to use a value of 0 for the constant in case of PCI devices, > what happens if we have multiple PCI controllers?
I guess we'd use the PCI Segment number for that? > [1] > https://www.kernel.org/doc/Documentation/devicetree/bindings/pci/pci-iommu.txt > [2] > https://www.kernel.org/doc/Documentation/devicetree/bindings/pci/pci-msi.txt > > Thanks, > > Diana >
