| /* |
| * Copyright 2010 |
| * by Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> |
| * |
| * 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 <linux/bootmem.h> |
| #include <linux/dma-mapping.h> |
| #include <xen/swiotlb-xen.h> |
| #include <xen/page.h> |
| #include <xen/xen-ops.h> |
| /* |
| * 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. |
| */ |
| |
| 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; |
| unsigned long nr_tbl; |
| |
| nr_tbl = swioltb_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); |
| } |
| |
| 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) |
| panic("Cannot allocate SWIOTLB buffer"); |
| |
| 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) |
| 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: |
| panic("DMA(%d): Failed to exchange pages allocated for DMA with Xen! "\ |
| "We either don't have the permission or you do not have enough"\ |
| "free memory under 4GB!\n", rc); |
| } |
| |
| void * |
| xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size, |
| dma_addr_t *dma_handle, gfp_t flags) |
| { |
| void *ret; |
| int order = get_order(size); |
| u64 dma_mask = DMA_BIT_MASK(32); |
| unsigned long vstart; |
| |
| /* |
| * 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 (hwdev && hwdev->coherent_dma_mask) |
| dma_mask = dma_alloc_coherent_mask(hwdev, flags); |
| |
| if (ret) { |
| if (xen_create_contiguous_region(vstart, order, |
| fls64(dma_mask)) != 0) { |
| free_pages(vstart, order); |
| return NULL; |
| } |
| memset(ret, 0, size); |
| *dma_handle = virt_to_machine(ret).maddr; |
| } |
| 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) |
| { |
| int order = get_order(size); |
| |
| if (dma_release_from_coherent(hwdev, order, vaddr)) |
| return; |
| |
| 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); |