1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/cpu.h>
3 #include <linux/dma-noncoherent.h>
4 #include <linux/gfp.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>
13
14 #include <xen/xen.h>
15 #include <xen/interface/grant_table.h>
16 #include <xen/interface/memory.h>
17 #include <xen/page.h>
18 #include <xen/swiotlb-xen.h>
19
20 #include <asm/cacheflush.h>
21 #include <asm/xen/hypercall.h>
22 #include <asm/xen/interface.h>
23
xen_get_swiotlb_free_pages(unsigned int order)24 unsigned long xen_get_swiotlb_free_pages(unsigned int order)
25 {
26 struct memblock_region *reg;
27 gfp_t flags = __GFP_NOWARN|__GFP_KSWAPD_RECLAIM;
28
29 for_each_memblock(memory, reg) {
30 if (reg->base < (phys_addr_t)0xffffffff) {
31 if (IS_ENABLED(CONFIG_ZONE_DMA32))
32 flags |= __GFP_DMA32;
33 else
34 flags |= __GFP_DMA;
35 break;
36 }
37 }
38 return __get_free_pages(flags, order);
39 }
40
41 static bool hypercall_cflush = false;
42
43 /* buffers in highmem or foreign pages cannot cross page boundaries */
dma_cache_maint(dma_addr_t handle,size_t size,u32 op)44 static void dma_cache_maint(dma_addr_t handle, size_t size, u32 op)
45 {
46 struct gnttab_cache_flush cflush;
47
48 cflush.a.dev_bus_addr = handle & XEN_PAGE_MASK;
49 cflush.offset = xen_offset_in_page(handle);
50 cflush.op = op;
51
52 do {
53 if (size + cflush.offset > XEN_PAGE_SIZE)
54 cflush.length = XEN_PAGE_SIZE - cflush.offset;
55 else
56 cflush.length = size;
57
58 HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1);
59
60 cflush.offset = 0;
61 cflush.a.dev_bus_addr += cflush.length;
62 size -= cflush.length;
63 } while (size);
64 }
65
66 /*
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.
72 */
xen_dma_sync_for_cpu(struct device * dev,dma_addr_t handle,phys_addr_t paddr,size_t size,enum dma_data_direction dir)73 void xen_dma_sync_for_cpu(struct device *dev, dma_addr_t handle,
74 phys_addr_t paddr, size_t size, enum dma_data_direction dir)
75 {
76 if (pfn_valid(PFN_DOWN(handle)))
77 arch_sync_dma_for_cpu(dev, paddr, size, dir);
78 else if (dir != DMA_TO_DEVICE)
79 dma_cache_maint(handle, size, GNTTAB_CACHE_INVAL);
80 }
81
xen_dma_sync_for_device(struct device * dev,dma_addr_t handle,phys_addr_t paddr,size_t size,enum dma_data_direction dir)82 void xen_dma_sync_for_device(struct device *dev, dma_addr_t handle,
83 phys_addr_t paddr, size_t size, enum dma_data_direction dir)
84 {
85 if (pfn_valid(PFN_DOWN(handle)))
86 arch_sync_dma_for_device(dev, paddr, size, dir);
87 else if (dir == DMA_FROM_DEVICE)
88 dma_cache_maint(handle, size, GNTTAB_CACHE_INVAL);
89 else
90 dma_cache_maint(handle, size, GNTTAB_CACHE_CLEAN);
91 }
92
xen_arch_need_swiotlb(struct device * dev,phys_addr_t phys,dma_addr_t dev_addr)93 bool xen_arch_need_swiotlb(struct device *dev,
94 phys_addr_t phys,
95 dma_addr_t dev_addr)
96 {
97 unsigned int xen_pfn = XEN_PFN_DOWN(phys);
98 unsigned int bfn = XEN_PFN_DOWN(dev_addr);
99
100 /*
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
105 *
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.
110 *
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.
114 */
115 return (!hypercall_cflush && (xen_pfn != bfn) &&
116 !dev_is_dma_coherent(dev));
117 }
118
xen_create_contiguous_region(phys_addr_t pstart,unsigned int order,unsigned int address_bits,dma_addr_t * dma_handle)119 int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
120 unsigned int address_bits,
121 dma_addr_t *dma_handle)
122 {
123 if (!xen_initial_domain())
124 return -EINVAL;
125
126 /* we assume that dom0 is mapped 1:1 for now */
127 *dma_handle = pstart;
128 return 0;
129 }
130
xen_destroy_contiguous_region(phys_addr_t pstart,unsigned int order)131 void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
132 {
133 return;
134 }
135
xen_mm_init(void)136 int __init xen_mm_init(void)
137 {
138 struct gnttab_cache_flush cflush;
139 if (!xen_initial_domain())
140 return 0;
141 xen_swiotlb_init(1, false);
142
143 cflush.op = 0;
144 cflush.a.dev_bus_addr = 0;
145 cflush.offset = 0;
146 cflush.length = 0;
147 if (HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1) != -ENOSYS)
148 hypercall_cflush = true;
149 return 0;
150 }
151 arch_initcall(xen_mm_init);
152
