On 20/04/17 19:04, Jonas Pfefferle1 wrote: > Alexey Kardashevskiy <a...@ozlabs.ru> wrote on 20/04/2017 09:24:02: > >> From: Alexey Kardashevskiy <a...@ozlabs.ru> >> To: dev@dpdk.org >> Cc: Alexey Kardashevskiy <a...@ozlabs.ru>, j...@zurich.ibm.com, >> Gowrishankar Muthukrishnan <gowrishanka...@in.ibm.com> >> Date: 20/04/2017 09:24 >> Subject: [PATCH dpdk 5/5] RFC: vfio/ppc64/spapr: Use correct bus >> addresses for DMA map >> >> VFIO_IOMMU_SPAPR_TCE_CREATE ioctl() returns the actual bus address for >> just created DMA window. It happens to start from zero because the default >> window is removed (leaving no windows) and new window starts from zero. >> However this is not guaranteed and the new window may start from another >> address, this adds an error check. >> >> Another issue is that IOVA passed to VFIO_IOMMU_MAP_DMA should be a PCI >> bus address while in this case a physical address of a user page is used. >> This changes IOVA to start from zero in a hope that the rest of DPDK >> expects this. > > This is not the case. DPDK expects a 1:1 mapping PA==IOVA. It will use the > phys_addr of the memory segment it got from /proc/self/pagemap cf. > librte_eal/linuxapp/eal/eal_memory.c. We could try setting it here to the > actual iova which basically makes the whole virtual to phyiscal mapping > with pagemap unnecessary which I believe should be the case for VFIO > anyway. Pagemap should only be needed when using pci_uio.
Ah, ok, makes sense now. But it sure needs a big fat comment there as it is not obvious why host RAM address is used there as DMA window start is not guaranteed. > >> >> Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru> >> --- >> lib/librte_eal/linuxapp/eal/eal_vfio.c | 12 ++++++++++-- >> 1 file changed, 10 insertions(+), 2 deletions(-) >> >> diff --git a/lib/librte_eal/linuxapp/eal/eal_vfio.c b/lib/ >> librte_eal/linuxapp/eal/eal_vfio.c >> index 46f951f4d..8b8e75c4f 100644 >> --- a/lib/librte_eal/linuxapp/eal/eal_vfio.c >> +++ b/lib/librte_eal/linuxapp/eal/eal_vfio.c >> @@ -658,7 +658,7 @@ vfio_spapr_dma_map(int vfio_container_fd) >> { >> const struct rte_memseg *ms = rte_eal_get_physmem_layout(); >> int i, ret; >> - >> + phys_addr_t io_offset; >> struct vfio_iommu_spapr_register_memory reg = { >> .argsz = sizeof(reg), >> .flags = 0 >> @@ -702,6 +702,13 @@ vfio_spapr_dma_map(int vfio_container_fd) >> return -1; >> } >> >> + io_offset = create.start_addr; >> + if (io_offset) { >> + RTE_LOG(ERR, EAL, " DMA offsets other than zero is not supported, " >> + "new window is created at %lx\n", io_offset); >> + return -1; >> + } >> + >> /* map all DPDK segments for DMA. use 1:1 PA to IOVA mapping */ >> for (i = 0; i < RTE_MAX_MEMSEG; i++) { >> struct vfio_iommu_type1_dma_map dma_map; >> @@ -723,7 +730,7 @@ vfio_spapr_dma_map(int vfio_container_fd) >> dma_map.argsz = sizeof(struct vfio_iommu_type1_dma_map); >> dma_map.vaddr = ms[i].addr_64; >> dma_map.size = ms[i].len; >> - dma_map.iova = ms[i].phys_addr; >> + dma_map.iova = io_offset; >> dma_map.flags = VFIO_DMA_MAP_FLAG_READ | >> VFIO_DMA_MAP_FLAG_WRITE; >> >> @@ -735,6 +742,7 @@ vfio_spapr_dma_map(int vfio_container_fd) >> return -1; >> } >> >> + io_offset += dma_map.size; >> } >> >> return 0; >> -- >> 2.11.0 >> > -- Alexey