| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * Copyright 2010 |
| * by Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> |
| * |
| * 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 <linux/memblock.h> |
| #include <linux/dma-direct.h> |
| #include <linux/dma-map-ops.h> |
| #include <linux/export.h> |
| #include <xen/swiotlb-xen.h> |
| #include <xen/page.h> |
| #include <xen/xen-ops.h> |
| #include <xen/hvc-console.h> |
| |
| #include <asm/dma-mapping.h> |
| #include <asm/xen/page-coherent.h> |
| |
| #include <trace/events/swiotlb.h> |
| #define MAX_DMA_BITS 32 |
| |
| /* |
| * 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 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 is_swiotlb_buffer(paddr); |
| return 0; |
| } |
| |
| static int xen_swiotlb_fixup(void *buf, 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; |
| } |
| |
| 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 ""; |
| } |
| |
| #define DEFAULT_NSLABS ALIGN(SZ_64M >> IO_TLB_SHIFT, IO_TLB_SEGSIZE) |
| |
| int __ref xen_swiotlb_init(void) |
| { |
| enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN; |
| unsigned long bytes = swiotlb_size_or_default(); |
| unsigned long nslabs = bytes >> IO_TLB_SHIFT; |
| unsigned int order, repeat = 3; |
| int rc = -ENOMEM; |
| char *start; |
| |
| retry: |
| m_ret = XEN_SWIOTLB_ENOMEM; |
| order = get_order(bytes); |
| |
| /* |
| * Get IO TLB memory from any location. |
| */ |
| #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) { |
| start = (void *)xen_get_swiotlb_free_pages(order); |
| if (start) |
| break; |
| order--; |
| } |
| if (!start) |
| goto error; |
| if (order != get_order(bytes)) { |
| pr_warn("Warning: only able to allocate %ld MB for software IO TLB\n", |
| (PAGE_SIZE << order) >> 20); |
| nslabs = SLABS_PER_PAGE << order; |
| bytes = nslabs << IO_TLB_SHIFT; |
| } |
| |
| /* |
| * And replace that memory with pages under 4GB. |
| */ |
| rc = xen_swiotlb_fixup(start, nslabs); |
| if (rc) { |
| free_pages((unsigned long)start, order); |
| m_ret = XEN_SWIOTLB_EFIXUP; |
| goto error; |
| } |
| rc = swiotlb_late_init_with_tbl(start, nslabs); |
| if (rc) |
| return rc; |
| swiotlb_set_max_segment(PAGE_SIZE); |
| return 0; |
| error: |
| if (repeat--) { |
| /* Min is 2MB */ |
| nslabs = max(1024UL, (nslabs >> 1)); |
| pr_info("Lowering to %luMB\n", |
| (nslabs << IO_TLB_SHIFT) >> 20); |
| goto retry; |
| } |
| pr_err("%s (rc:%d)\n", xen_swiotlb_error(m_ret), rc); |
| free_pages((unsigned long)start, order); |
| return rc; |
| } |
| |
| #ifdef CONFIG_X86 |
| void __init xen_swiotlb_init_early(void) |
| { |
| unsigned long bytes = swiotlb_size_or_default(); |
| unsigned long nslabs = bytes >> IO_TLB_SHIFT; |
| unsigned int repeat = 3; |
| char *start; |
| int rc; |
| |
| retry: |
| /* |
| * Get IO TLB memory from any location. |
| */ |
| start = memblock_alloc(PAGE_ALIGN(bytes), PAGE_SIZE); |
| if (!start) |
| panic("%s: Failed to allocate %lu bytes align=0x%lx\n", |
| __func__, PAGE_ALIGN(bytes), PAGE_SIZE); |
| |
| /* |
| * And replace that memory with pages under 4GB. |
| */ |
| rc = xen_swiotlb_fixup(start, nslabs); |
| if (rc) { |
| memblock_free(__pa(start), PAGE_ALIGN(bytes)); |
| if (repeat--) { |
| /* Min is 2MB */ |
| nslabs = max(1024UL, (nslabs >> 1)); |
| bytes = nslabs << IO_TLB_SHIFT; |
| pr_info("Lowering to %luMB\n", bytes >> 20); |
| goto retry; |
| } |
| panic("%s (rc:%d)", xen_swiotlb_error(XEN_SWIOTLB_EFIXUP), rc); |
| } |
| |
| if (swiotlb_init_with_tbl(start, nslabs, false)) |
| panic("Cannot allocate SWIOTLB buffer"); |
| swiotlb_set_max_segment(PAGE_SIZE); |
| } |
| #endif /* CONFIG_X86 */ |
| |
| 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, 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, 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, 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_sync_single_for_cpu(dev, paddr, size, dir); |
| } |
| |
| 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_sync_single_for_device(dev, paddr, size, dir); |
| |
| 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_phys_to_dma(hwdev, io_tlb_default_mem->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, |
| }; |