/* * Copyright 2010 * by Konrad Rzeszutek Wilk * * This code provides a IOMMU for Xen PV guests with PCI passthrough. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License v2.0 as published by * the Free Software Foundation * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * PV guests under Xen are running in an non-contiguous memory architecture. * * When PCI pass-through is utilized, this necessitates an IOMMU for * translating bus (DMA) to virtual and vice-versa and also providing a * mechanism to have contiguous pages for device drivers operations (say DMA * operations). * * Specifically, under Xen the Linux idea of pages is an illusion. It * assumes that pages start at zero and go up to the available memory. To * help with that, the Linux Xen MMU provides a lookup mechanism to * translate the page frame numbers (PFN) to machine frame numbers (MFN) * and vice-versa. The MFN are the "real" frame numbers. Furthermore * memory is not contiguous. Xen hypervisor stitches memory for guests * from different pools, which means there is no guarantee that PFN==MFN * and PFN+1==MFN+1. Lastly with Xen 4.0, pages (in debug mode) are * allocated in descending order (high to low), meaning the guest might * never get any MFN's under the 4GB mark. * */ #include #include #include #include #include #include #include /* * Used to do a quick range check in swiotlb_tbl_unmap_single and * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this * API. */ static char *xen_io_tlb_start, *xen_io_tlb_end; static unsigned long xen_io_tlb_nslabs; /* * Quick lookup value of the bus address of the IOTLB. */ static u64 start_dma_addr; static dma_addr_t xen_phys_to_bus(phys_addr_t paddr) { return phys_to_machine(XPADDR(paddr)).maddr; } static phys_addr_t xen_bus_to_phys(dma_addr_t baddr) { return machine_to_phys(XMADDR(baddr)).paddr; } static dma_addr_t xen_virt_to_bus(void *address) { return xen_phys_to_bus(virt_to_phys(address)); } static int check_pages_physically_contiguous(unsigned long pfn, unsigned int offset, size_t length) { unsigned long next_mfn; int i; int nr_pages; next_mfn = pfn_to_mfn(pfn); nr_pages = (offset + length + PAGE_SIZE-1) >> PAGE_SHIFT; for (i = 1; i < nr_pages; i++) { if (pfn_to_mfn(++pfn) != ++next_mfn) return 0; } return 1; } static int range_straddles_page_boundary(phys_addr_t p, size_t size) { unsigned long pfn = PFN_DOWN(p); unsigned int offset = p & ~PAGE_MASK; if (offset + size <= PAGE_SIZE) return 0; if (check_pages_physically_contiguous(pfn, offset, size)) return 0; return 1; } static int is_xen_swiotlb_buffer(dma_addr_t dma_addr) { unsigned long mfn = PFN_DOWN(dma_addr); unsigned long pfn = mfn_to_local_pfn(mfn); phys_addr_t paddr; /* If the address is outside our domain, it CAN * have the same virtual address as another address * in our domain. Therefore _only_ check address within our domain. */ if (pfn_valid(pfn)) { paddr = PFN_PHYS(pfn); return paddr >= virt_to_phys(xen_io_tlb_start) && paddr < virt_to_phys(xen_io_tlb_end); } return 0; } static int max_dma_bits = 32; static int xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs) { int i, rc; int dma_bits; dma_bits = get_order(IO_TLB_SEGSIZE << IO_TLB_SHIFT) + PAGE_SHIFT; i = 0; do { int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE); do { rc = xen_create_contiguous_region( (unsigned long)buf + (i << IO_TLB_SHIFT), get_order(slabs << IO_TLB_SHIFT), dma_bits); } while (rc && dma_bits++ < max_dma_bits); if (rc) return rc; i += slabs; } while (i < nslabs); return 0; } void __init xen_swiotlb_init(int verbose) { unsigned long bytes; int rc = -ENOMEM; unsigned long nr_tbl; char *m = NULL; unsigned int repeat = 3; nr_tbl = swiotlb_nr_tbl(); if (nr_tbl) xen_io_tlb_nslabs = nr_tbl; else { xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT); xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE); } retry: bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT; /* * Get IO TLB memory from any location. */ xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes)); if (!xen_io_tlb_start) { m = "Cannot allocate Xen-SWIOTLB buffer!\n"; goto error; } xen_io_tlb_end = xen_io_tlb_start + bytes; /* * And replace that memory with pages under 4GB. */ rc = xen_swiotlb_fixup(xen_io_tlb_start, bytes, xen_io_tlb_nslabs); if (rc) { free_bootmem(__pa(xen_io_tlb_start), PAGE_ALIGN(bytes)); m = "Failed to get contiguous memory for DMA from Xen!\n"\ "You either: don't have the permissions, do not have"\ " enough free memory under 4GB, or the hypervisor memory"\ "is too fragmented!"; goto error; } start_dma_addr = xen_virt_to_bus(xen_io_tlb_start); swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, verbose); return; error: if (repeat--) { xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */ (xen_io_tlb_nslabs >> 1)); printk(KERN_INFO "Xen-SWIOTLB: Lowering to %luMB\n", (xen_io_tlb_nslabs << IO_TLB_SHIFT) >> 20); goto retry; } xen_raw_printk("%s (rc:%d)", m, rc); panic("%s (rc:%d)", m, rc); } void * xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size, dma_addr_t *dma_handle, gfp_t flags, struct dma_attrs *attrs) { void *ret; int order = get_order(size); u64 dma_mask = DMA_BIT_MASK(32); unsigned long vstart; phys_addr_t phys; dma_addr_t dev_addr; /* * Ignore region specifiers - the kernel's ideas of * pseudo-phys memory layout has nothing to do with the * machine physical layout. We can't allocate highmem * because we can't return a pointer to it. */ flags &= ~(__GFP_DMA | __GFP_HIGHMEM); if (dma_alloc_from_coherent(hwdev, size, dma_handle, &ret)) return ret; vstart = __get_free_pages(flags, order); ret = (void *)vstart; if (!ret) return ret; if (hwdev && hwdev->coherent_dma_mask) dma_mask = hwdev->coherent_dma_mask; phys = virt_to_phys(ret); dev_addr = xen_phys_to_bus(phys); if (((dev_addr + size - 1 <= dma_mask)) && !range_straddles_page_boundary(phys, size)) *dma_handle = dev_addr; else { if (xen_create_contiguous_region(vstart, order, fls64(dma_mask)) != 0) { free_pages(vstart, order); return NULL; } *dma_handle = virt_to_machine(ret).maddr; } memset(ret, 0, size); return ret; } EXPORT_SYMBOL_GPL(xen_swiotlb_alloc_coherent); void xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr, dma_addr_t dev_addr, struct dma_attrs *attrs) { int order = get_order(size); phys_addr_t phys; u64 dma_mask = DMA_BIT_MASK(32); if (dma_release_from_coherent(hwdev, order, vaddr)) return; if (hwdev && hwdev->coherent_dma_mask) dma_mask = hwdev->coherent_dma_mask; phys = virt_to_phys(vaddr); if (((dev_addr + size - 1 > dma_mask)) || range_straddles_page_boundary(phys, size)) xen_destroy_contiguous_region((unsigned long)vaddr, order); free_pages((unsigned long)vaddr, order); } EXPORT_SYMBOL_GPL(xen_swiotlb_free_coherent); /* * Map a single buffer of the indicated size for DMA in streaming mode. The * physical address to use is returned. * * Once the device is given the dma address, the device owns this memory until * either xen_swiotlb_unmap_page or xen_swiotlb_dma_sync_single is performed. */ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page, unsigned long offset, size_t size, enum dma_data_direction dir, struct dma_attrs *attrs) { phys_addr_t phys = page_to_phys(page) + offset; dma_addr_t dev_addr = xen_phys_to_bus(phys); void *map; BUG_ON(dir == DMA_NONE); /* * If the address happens to be in the device's DMA window, * we can safely return the device addr and not worry about bounce * buffering it. */ if (dma_capable(dev, dev_addr, size) && !range_straddles_page_boundary(phys, size) && !swiotlb_force) return dev_addr; /* * Oh well, have to allocate and map a bounce buffer. */ map = swiotlb_tbl_map_single(dev, start_dma_addr, phys, size, dir); if (!map) return DMA_ERROR_CODE; dev_addr = xen_virt_to_bus(map); /* * Ensure that the address returned is DMA'ble */ if (!dma_capable(dev, dev_addr, size)) { swiotlb_tbl_unmap_single(dev, map, size, dir); dev_addr = 0; } return dev_addr; } EXPORT_SYMBOL_GPL(xen_swiotlb_map_page); /* * Unmap a single streaming mode DMA translation. The dma_addr and size must * match what was provided for in a previous xen_swiotlb_map_page call. All * other usages are undefined. * * After this call, reads by the cpu to the buffer are guaranteed to see * whatever the device wrote there. */ static void xen_unmap_single(struct device *hwdev, dma_addr_t dev_addr, size_t size, enum dma_data_direction dir) { phys_addr_t paddr = xen_bus_to_phys(dev_addr); BUG_ON(dir == DMA_NONE); /* NOTE: We use dev_addr here, not paddr! */ if (is_xen_swiotlb_buffer(dev_addr)) { swiotlb_tbl_unmap_single(hwdev, phys_to_virt(paddr), size, dir); return; } if (dir != DMA_FROM_DEVICE) return; /* * phys_to_virt doesn't work with hihgmem page but we could * call dma_mark_clean() with hihgmem page here. However, we * are fine since dma_mark_clean() is null on POWERPC. We can * make dma_mark_clean() take a physical address if necessary. */ dma_mark_clean(phys_to_virt(paddr), size); } void xen_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr, size_t size, enum dma_data_direction dir, struct dma_attrs *attrs) { xen_unmap_single(hwdev, dev_addr, size, dir); } EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_page); /* * Make physical memory consistent for a single streaming mode DMA translation * after a transfer. * * If you perform a xen_swiotlb_map_page() but wish to interrogate the buffer * using the cpu, yet do not wish to teardown the dma mapping, you must * call this function before doing so. At the next point you give the dma * address back to the card, you must first perform a * xen_swiotlb_dma_sync_for_device, and then the device again owns the buffer */ static void xen_swiotlb_sync_single(struct device *hwdev, dma_addr_t dev_addr, size_t size, enum dma_data_direction dir, enum dma_sync_target target) { phys_addr_t paddr = xen_bus_to_phys(dev_addr); BUG_ON(dir == DMA_NONE); /* NOTE: We use dev_addr here, not paddr! */ if (is_xen_swiotlb_buffer(dev_addr)) { swiotlb_tbl_sync_single(hwdev, phys_to_virt(paddr), size, dir, target); return; } if (dir != DMA_FROM_DEVICE) return; dma_mark_clean(phys_to_virt(paddr), size); } void xen_swiotlb_sync_single_for_cpu(struct device *hwdev, dma_addr_t dev_addr, size_t size, enum dma_data_direction dir) { xen_swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_CPU); } EXPORT_SYMBOL_GPL(xen_swiotlb_sync_single_for_cpu); void xen_swiotlb_sync_single_for_device(struct device *hwdev, dma_addr_t dev_addr, size_t size, enum dma_data_direction dir) { xen_swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_DEVICE); } EXPORT_SYMBOL_GPL(xen_swiotlb_sync_single_for_device); /* * Map a set of buffers described by scatterlist in streaming mode for DMA. * This is the scatter-gather version of the above xen_swiotlb_map_page * interface. Here the scatter gather list elements are each tagged with the * appropriate dma address and length. They are obtained via * sg_dma_{address,length}(SG). * * NOTE: An implementation may be able to use a smaller number of * DMA address/length pairs than there are SG table elements. * (for example via virtual mapping capabilities) * The routine returns the number of addr/length pairs actually * used, at most nents. * * Device ownership issues as mentioned above for xen_swiotlb_map_page are the * same here. */ int xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems, enum dma_data_direction dir, struct dma_attrs *attrs) { struct scatterlist *sg; int i; BUG_ON(dir == DMA_NONE); for_each_sg(sgl, sg, nelems, i) { phys_addr_t paddr = sg_phys(sg); dma_addr_t dev_addr = xen_phys_to_bus(paddr); if (swiotlb_force || !dma_capable(hwdev, dev_addr, sg->length) || range_straddles_page_boundary(paddr, sg->length)) { void *map = swiotlb_tbl_map_single(hwdev, start_dma_addr, sg_phys(sg), sg->length, dir); if (!map) { /* Don't panic here, we expect map_sg users to do proper error handling. */ xen_swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir, attrs); sgl[0].dma_length = 0; return DMA_ERROR_CODE; } sg->dma_address = xen_virt_to_bus(map); } else sg->dma_address = dev_addr; sg->dma_length = sg->length; } return nelems; } EXPORT_SYMBOL_GPL(xen_swiotlb_map_sg_attrs); int xen_swiotlb_map_sg(struct device *hwdev, struct scatterlist *sgl, int nelems, enum dma_data_direction dir) { return xen_swiotlb_map_sg_attrs(hwdev, sgl, nelems, dir, NULL); } EXPORT_SYMBOL_GPL(xen_swiotlb_map_sg); /* * Unmap a set of streaming mode DMA translations. Again, cpu read rules * concerning calls here are the same as for swiotlb_unmap_page() above. */ void xen_swiotlb_unmap_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems, enum dma_data_direction dir, struct dma_attrs *attrs) { struct scatterlist *sg; int i; BUG_ON(dir == DMA_NONE); for_each_sg(sgl, sg, nelems, i) xen_unmap_single(hwdev, sg->dma_address, sg->dma_length, dir); } EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_sg_attrs); void xen_swiotlb_unmap_sg(struct device *hwdev, struct scatterlist *sgl, int nelems, enum dma_data_direction dir) { return xen_swiotlb_unmap_sg_attrs(hwdev, sgl, nelems, dir, NULL); } EXPORT_SYMBOL_GPL(xen_swiotlb_unmap_sg); /* * Make physical memory consistent for a set of streaming mode DMA translations * after a transfer. * * The same as swiotlb_sync_single_* but for a scatter-gather list, same rules * and usage. */ static void xen_swiotlb_sync_sg(struct device *hwdev, struct scatterlist *sgl, int nelems, enum dma_data_direction dir, enum dma_sync_target target) { struct scatterlist *sg; int i; for_each_sg(sgl, sg, nelems, i) xen_swiotlb_sync_single(hwdev, sg->dma_address, sg->dma_length, dir, target); } void xen_swiotlb_sync_sg_for_cpu(struct device *hwdev, struct scatterlist *sg, int nelems, enum dma_data_direction dir) { xen_swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_CPU); } EXPORT_SYMBOL_GPL(xen_swiotlb_sync_sg_for_cpu); void xen_swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg, int nelems, enum dma_data_direction dir) { xen_swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_DEVICE); } EXPORT_SYMBOL_GPL(xen_swiotlb_sync_sg_for_device); int xen_swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr) { return !dma_addr; } EXPORT_SYMBOL_GPL(xen_swiotlb_dma_mapping_error); /* * Return whether the given device DMA address mask can be supported * properly. For example, if your device can only drive the low 24-bits * during bus mastering, then you would pass 0x00ffffff as the mask to * this function. */ int xen_swiotlb_dma_supported(struct device *hwdev, u64 mask) { return xen_virt_to_bus(xen_io_tlb_end - 1) <= mask; } EXPORT_SYMBOL_GPL(xen_swiotlb_dma_supported);