1 // SPDX-License-Identifier: GPL-2.0-only
3 #include <linux/dma-noncoherent.h>
5 #include <linux/highmem.h>
6 #include <linux/export.h>
7 #include <linux/memblock.h>
8 #include <linux/of_address.h>
9 #include <linux/slab.h>
10 #include <linux/types.h>
11 #include <linux/vmalloc.h>
12 #include <linux/swiotlb.h>
15 #include <xen/interface/grant_table.h>
16 #include <xen/interface/memory.h>
18 #include <xen/swiotlb-xen.h>
20 #include <asm/cacheflush.h>
21 #include <asm/xen/hypercall.h>
22 #include <asm/xen/interface.h>
24 unsigned long xen_get_swiotlb_free_pages(unsigned int order)
26 struct memblock_region *reg;
27 gfp_t flags = __GFP_NOWARN|__GFP_KSWAPD_RECLAIM;
29 for_each_memblock(memory, reg) {
30 if (reg->base < (phys_addr_t)0xffffffff) {
31 if (IS_ENABLED(CONFIG_ZONE_DMA32))
38 return __get_free_pages(flags, order);
41 static bool hypercall_cflush = false;
43 /* buffers in highmem or foreign pages cannot cross page boundaries */
44 static void dma_cache_maint(dma_addr_t handle, size_t size, u32 op)
46 struct gnttab_cache_flush cflush;
48 cflush.a.dev_bus_addr = handle & XEN_PAGE_MASK;
49 cflush.offset = xen_offset_in_page(handle);
53 if (size + cflush.offset > XEN_PAGE_SIZE)
54 cflush.length = XEN_PAGE_SIZE - cflush.offset;
58 HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1);
61 cflush.a.dev_bus_addr += cflush.length;
62 size -= cflush.length;
67 * Dom0 is mapped 1:1, and while the Linux page can span across multiple Xen
68 * pages, it is not possible for it to contain a mix of local and foreign Xen
69 * pages. Calling pfn_valid on a foreign mfn will always return false, so if
70 * pfn_valid returns true the pages is local and we can use the native
71 * dma-direct functions, otherwise we call the Xen specific version.
73 void xen_dma_sync_for_cpu(dma_addr_t handle, phys_addr_t paddr, size_t size,
74 enum dma_data_direction dir)
76 if (pfn_valid(PFN_DOWN(handle)))
77 arch_sync_dma_for_cpu(paddr, size, dir);
78 else if (dir != DMA_TO_DEVICE)
79 dma_cache_maint(handle, size, GNTTAB_CACHE_INVAL);
82 void xen_dma_sync_for_device(dma_addr_t handle, phys_addr_t paddr, size_t size,
83 enum dma_data_direction dir)
85 if (pfn_valid(PFN_DOWN(handle)))
86 arch_sync_dma_for_device(paddr, size, dir);
87 else if (dir == DMA_FROM_DEVICE)
88 dma_cache_maint(handle, size, GNTTAB_CACHE_INVAL);
90 dma_cache_maint(handle, size, GNTTAB_CACHE_CLEAN);
93 bool xen_arch_need_swiotlb(struct device *dev,
97 unsigned int xen_pfn = XEN_PFN_DOWN(phys);
98 unsigned int bfn = XEN_PFN_DOWN(dev_addr);
101 * The swiotlb buffer should be used if
102 * - Xen doesn't have the cache flush hypercall
103 * - The Linux page refers to foreign memory
104 * - The device doesn't support coherent DMA request
106 * The Linux page may be spanned acrros multiple Xen page, although
107 * it's not possible to have a mix of local and foreign Xen page.
108 * Furthermore, range_straddles_page_boundary is already checking
109 * if buffer is physically contiguous in the host RAM.
111 * Therefore we only need to check the first Xen page to know if we
112 * require a bounce buffer because the device doesn't support coherent
113 * memory and we are not able to flush the cache.
115 return (!hypercall_cflush && (xen_pfn != bfn) &&
116 !dev_is_dma_coherent(dev));
119 int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
120 unsigned int address_bits,
121 dma_addr_t *dma_handle)
123 if (!xen_initial_domain())
126 /* we assume that dom0 is mapped 1:1 for now */
127 *dma_handle = pstart;
131 void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
136 int __init xen_mm_init(void)
138 struct gnttab_cache_flush cflush;
139 if (!xen_initial_domain())
141 xen_swiotlb_init(1, false);
144 cflush.a.dev_bus_addr = 0;
147 if (HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1) != -ENOSYS)
148 hypercall_cflush = true;
151 arch_initcall(xen_mm_init);