// SPDX-License-Identifier: GPL-2.0-only /* * Copyright 2010 * by Konrad Rzeszutek Wilk * * This code provides a IOMMU for Xen PV guests with PCI passthrough. * * 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. */ #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #define MAX_DMA_BITS 32 /* * 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 inline phys_addr_t xen_phys_to_bus(struct device *dev, phys_addr_t paddr) { unsigned long bfn = pfn_to_bfn(XEN_PFN_DOWN(paddr)); phys_addr_t baddr = (phys_addr_t)bfn << XEN_PAGE_SHIFT; baddr |= paddr & ~XEN_PAGE_MASK; return baddr; } static inline dma_addr_t xen_phys_to_dma(struct device *dev, phys_addr_t paddr) { return phys_to_dma(dev, xen_phys_to_bus(dev, paddr)); } static inline phys_addr_t xen_bus_to_phys(struct device *dev, phys_addr_t baddr) { unsigned long xen_pfn = bfn_to_pfn(XEN_PFN_DOWN(baddr)); phys_addr_t paddr = (xen_pfn << XEN_PAGE_SHIFT) | (baddr & ~XEN_PAGE_MASK); return paddr; } static inline phys_addr_t xen_dma_to_phys(struct device *dev, dma_addr_t dma_addr) { return xen_bus_to_phys(dev, dma_to_phys(dev, dma_addr)); } static inline dma_addr_t xen_virt_to_bus(struct device *dev, void *address) { return xen_phys_to_dma(dev, virt_to_phys(address)); } static inline int range_straddles_page_boundary(phys_addr_t p, size_t size) { unsigned long next_bfn, xen_pfn = XEN_PFN_DOWN(p); unsigned int i, nr_pages = XEN_PFN_UP(xen_offset_in_page(p) + size); next_bfn = pfn_to_bfn(xen_pfn); for (i = 1; i < nr_pages; i++) if (pfn_to_bfn(++xen_pfn) != ++next_bfn) return 1; return 0; } static int is_xen_swiotlb_buffer(struct device *dev, dma_addr_t dma_addr) { unsigned long bfn = XEN_PFN_DOWN(dma_to_phys(dev, dma_addr)); unsigned long xen_pfn = bfn_to_local_pfn(bfn); phys_addr_t paddr = (phys_addr_t)xen_pfn << XEN_PAGE_SHIFT; /* 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_DOWN(paddr))) { return paddr >= virt_to_phys(xen_io_tlb_start) && paddr < virt_to_phys(xen_io_tlb_end); } return 0; } static int xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs) { int i, rc; int dma_bits; dma_addr_t dma_handle; phys_addr_t p = virt_to_phys(buf); 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( p + (i << IO_TLB_SHIFT), get_order(slabs << IO_TLB_SHIFT), dma_bits, &dma_handle); } while (rc && dma_bits++ < MAX_DMA_BITS); if (rc) return rc; i += slabs; } while (i < nslabs); return 0; } static unsigned long xen_set_nslabs(unsigned long nr_tbl) { if (!nr_tbl) { xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT); xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE); } else xen_io_tlb_nslabs = nr_tbl; return xen_io_tlb_nslabs << IO_TLB_SHIFT; } enum xen_swiotlb_err { XEN_SWIOTLB_UNKNOWN = 0, XEN_SWIOTLB_ENOMEM, XEN_SWIOTLB_EFIXUP }; static const char *xen_swiotlb_error(enum xen_swiotlb_err err) { switch (err) { case XEN_SWIOTLB_ENOMEM: return "Cannot allocate Xen-SWIOTLB buffer\n"; case XEN_SWIOTLB_EFIXUP: return "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!"; default: break; } return ""; } int __ref xen_swiotlb_init(int verbose, bool early) { unsigned long bytes, order; int rc = -ENOMEM; enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN; unsigned int repeat = 3; xen_io_tlb_nslabs = swiotlb_nr_tbl(); retry: bytes = xen_set_nslabs(xen_io_tlb_nslabs); order = get_order(xen_io_tlb_nslabs << IO_TLB_SHIFT); /* * IO TLB memory already allocated. Just use it. */ if (io_tlb_start != 0) { xen_io_tlb_start = phys_to_virt(io_tlb_start); goto end; } /* * Get IO TLB memory from any location. */ if (early) { xen_io_tlb_start = memblock_alloc(PAGE_ALIGN(bytes), PAGE_SIZE); if (!xen_io_tlb_start) panic("%s: Failed to allocate %lu bytes align=0x%lx\n", __func__, PAGE_ALIGN(bytes), PAGE_SIZE); } else { #define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT)) #define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT) while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) { xen_io_tlb_start = (void *)xen_get_swiotlb_free_pages(order); if (xen_io_tlb_start) break; order--; } if (order != get_order(bytes)) { pr_warn("Warning: only able to allocate %ld MB for software IO TLB\n", (PAGE_SIZE << order) >> 20); xen_io_tlb_nslabs = SLABS_PER_PAGE << order; bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT; } } if (!xen_io_tlb_start) { m_ret = XEN_SWIOTLB_ENOMEM; goto error; } /* * And replace that memory with pages under 4GB. */ rc = xen_swiotlb_fixup(xen_io_tlb_start, bytes, xen_io_tlb_nslabs); if (rc) { if (early) memblock_free(__pa(xen_io_tlb_start), PAGE_ALIGN(bytes)); else { free_pages((unsigned long)xen_io_tlb_start, order); xen_io_tlb_start = NULL; } m_ret = XEN_SWIOTLB_EFIXUP; goto error; } if (early) { if (swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, verbose)) panic("Cannot allocate SWIOTLB buffer"); rc = 0; } else rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs); end: xen_io_tlb_end = xen_io_tlb_start + bytes; if (!rc) swiotlb_set_max_segment(PAGE_SIZE); return rc; error: if (repeat--) { xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */ (xen_io_tlb_nslabs >> 1)); pr_info("Lowering to %luMB\n", (xen_io_tlb_nslabs << IO_TLB_SHIFT) >> 20); goto retry; } pr_err("%s (rc:%d)\n", xen_swiotlb_error(m_ret), rc); if (early) panic("%s (rc:%d)", xen_swiotlb_error(m_ret), rc); else free_pages((unsigned long)xen_io_tlb_start, order); return rc; } static void * xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size, dma_addr_t *dma_handle, gfp_t flags, unsigned long attrs) { void *ret; int order = get_order(size); u64 dma_mask = DMA_BIT_MASK(32); 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); /* Convert the size to actually allocated. */ size = 1UL << (order + XEN_PAGE_SHIFT); /* On ARM this function returns an ioremap'ped virtual address for * which virt_to_phys doesn't return the corresponding physical * address. In fact on ARM virt_to_phys only works for kernel direct * mapped RAM memory. Also see comment below. */ ret = xen_alloc_coherent_pages(hwdev, size, dma_handle, flags, attrs); if (!ret) return ret; if (hwdev && hwdev->coherent_dma_mask) dma_mask = hwdev->coherent_dma_mask; /* At this point dma_handle is the dma address, next we are * going to set it to the machine address. * Do not use virt_to_phys(ret) because on ARM it doesn't correspond * to *dma_handle. */ phys = dma_to_phys(hwdev, *dma_handle); dev_addr = xen_phys_to_dma(hwdev, phys); if (((dev_addr + size - 1 <= dma_mask)) && !range_straddles_page_boundary(phys, size)) *dma_handle = dev_addr; else { if (xen_create_contiguous_region(phys, order, fls64(dma_mask), dma_handle) != 0) { xen_free_coherent_pages(hwdev, size, ret, (dma_addr_t)phys, attrs); return NULL; } *dma_handle = phys_to_dma(hwdev, *dma_handle); SetPageXenRemapped(virt_to_page(ret)); } memset(ret, 0, size); return ret; } static void xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr, dma_addr_t dev_addr, unsigned long attrs) { int order = get_order(size); phys_addr_t phys; u64 dma_mask = DMA_BIT_MASK(32); struct page *page; if (hwdev && hwdev->coherent_dma_mask) dma_mask = hwdev->coherent_dma_mask; /* do not use virt_to_phys because on ARM it doesn't return you the * physical address */ phys = xen_dma_to_phys(hwdev, dev_addr); /* Convert the size to actually allocated. */ size = 1UL << (order + XEN_PAGE_SHIFT); if (is_vmalloc_addr(vaddr)) page = vmalloc_to_page(vaddr); else page = virt_to_page(vaddr); if (!WARN_ON((dev_addr + size - 1 > dma_mask) || range_straddles_page_boundary(phys, size)) && TestClearPageXenRemapped(page)) xen_destroy_contiguous_region(phys, order); xen_free_coherent_pages(hwdev, size, vaddr, phys_to_dma(hwdev, phys), attrs); } /* * 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. */ static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page, unsigned long offset, size_t size, enum dma_data_direction dir, unsigned long attrs) { phys_addr_t map, phys = page_to_phys(page) + offset; dma_addr_t dev_addr = xen_phys_to_dma(dev, phys); 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, true) && !range_straddles_page_boundary(phys, size) && !xen_arch_need_swiotlb(dev, phys, dev_addr) && swiotlb_force != SWIOTLB_FORCE) goto done; /* * Oh well, have to allocate and map a bounce buffer. */ trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force); map = swiotlb_tbl_map_single(dev, virt_to_phys(xen_io_tlb_start), phys, size, size, dir, attrs); if (map == (phys_addr_t)DMA_MAPPING_ERROR) return DMA_MAPPING_ERROR; phys = map; dev_addr = xen_phys_to_dma(dev, map); /* * Ensure that the address returned is DMA'ble */ if (unlikely(!dma_capable(dev, dev_addr, size, true))) { swiotlb_tbl_unmap_single(dev, map, size, size, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC); return DMA_MAPPING_ERROR; } done: if (!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) { if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dev_addr)))) arch_sync_dma_for_device(phys, size, dir); else xen_dma_sync_for_device(dev, dev_addr, size, dir); } return dev_addr; } /* * 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_swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr, size_t size, enum dma_data_direction dir, unsigned long attrs) { phys_addr_t paddr = xen_dma_to_phys(hwdev, dev_addr); BUG_ON(dir == DMA_NONE); if (!dev_is_dma_coherent(hwdev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) { if (pfn_valid(PFN_DOWN(dma_to_phys(hwdev, dev_addr)))) arch_sync_dma_for_cpu(paddr, size, dir); else xen_dma_sync_for_cpu(hwdev, dev_addr, size, dir); } /* NOTE: We use dev_addr here, not paddr! */ if (is_xen_swiotlb_buffer(hwdev, dev_addr)) swiotlb_tbl_unmap_single(hwdev, paddr, size, size, dir, attrs); } static void xen_swiotlb_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr, size_t size, enum dma_data_direction dir) { phys_addr_t paddr = xen_dma_to_phys(dev, dma_addr); if (!dev_is_dma_coherent(dev)) { if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dma_addr)))) arch_sync_dma_for_cpu(paddr, size, dir); else xen_dma_sync_for_cpu(dev, dma_addr, size, dir); } if (is_xen_swiotlb_buffer(dev, dma_addr)) swiotlb_tbl_sync_single(dev, paddr, size, dir, SYNC_FOR_CPU); } static void xen_swiotlb_sync_single_for_device(struct device *dev, dma_addr_t dma_addr, size_t size, enum dma_data_direction dir) { phys_addr_t paddr = xen_dma_to_phys(dev, dma_addr); if (is_xen_swiotlb_buffer(dev, dma_addr)) swiotlb_tbl_sync_single(dev, paddr, size, dir, SYNC_FOR_DEVICE); if (!dev_is_dma_coherent(dev)) { if (pfn_valid(PFN_DOWN(dma_to_phys(dev, dma_addr)))) arch_sync_dma_for_device(paddr, size, dir); else xen_dma_sync_for_device(dev, dma_addr, size, dir); } } /* * Unmap a set of streaming mode DMA translations. Again, cpu read rules * concerning calls here are the same as for swiotlb_unmap_page() above. */ static void xen_swiotlb_unmap_sg(struct device *hwdev, struct scatterlist *sgl, int nelems, enum dma_data_direction dir, unsigned long attrs) { struct scatterlist *sg; int i; BUG_ON(dir == DMA_NONE); for_each_sg(sgl, sg, nelems, i) xen_swiotlb_unmap_page(hwdev, sg->dma_address, sg_dma_len(sg), dir, attrs); } static int xen_swiotlb_map_sg(struct device *dev, struct scatterlist *sgl, int nelems, enum dma_data_direction dir, unsigned long attrs) { struct scatterlist *sg; int i; BUG_ON(dir == DMA_NONE); for_each_sg(sgl, sg, nelems, i) { sg->dma_address = xen_swiotlb_map_page(dev, sg_page(sg), sg->offset, sg->length, dir, attrs); if (sg->dma_address == DMA_MAPPING_ERROR) goto out_unmap; sg_dma_len(sg) = sg->length; } return nelems; out_unmap: xen_swiotlb_unmap_sg(dev, sgl, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC); sg_dma_len(sgl) = 0; return 0; } static void xen_swiotlb_sync_sg_for_cpu(struct device *dev, struct scatterlist *sgl, int nelems, enum dma_data_direction dir) { struct scatterlist *sg; int i; for_each_sg(sgl, sg, nelems, i) { xen_swiotlb_sync_single_for_cpu(dev, sg->dma_address, sg->length, dir); } } static void xen_swiotlb_sync_sg_for_device(struct device *dev, struct scatterlist *sgl, int nelems, enum dma_data_direction dir) { struct scatterlist *sg; int i; for_each_sg(sgl, sg, nelems, i) { xen_swiotlb_sync_single_for_device(dev, sg->dma_address, sg->length, dir); } } /* * 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. */ static int xen_swiotlb_dma_supported(struct device *hwdev, u64 mask) { return xen_virt_to_bus(hwdev, xen_io_tlb_end - 1) <= mask; } const struct dma_map_ops xen_swiotlb_dma_ops = { .alloc = xen_swiotlb_alloc_coherent, .free = xen_swiotlb_free_coherent, .sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu, .sync_single_for_device = xen_swiotlb_sync_single_for_device, .sync_sg_for_cpu = xen_swiotlb_sync_sg_for_cpu, .sync_sg_for_device = xen_swiotlb_sync_sg_for_device, .map_sg = xen_swiotlb_map_sg, .unmap_sg = xen_swiotlb_unmap_sg, .map_page = xen_swiotlb_map_page, .unmap_page = xen_swiotlb_unmap_page, .dma_supported = xen_swiotlb_dma_supported, .mmap = dma_common_mmap, .get_sgtable = dma_common_get_sgtable, .alloc_pages = dma_common_alloc_pages, .free_pages = dma_common_free_pages, };