1#include <linux/cpu.h>
2#include <linux/dma-mapping.h>
3#include <linux/bootmem.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/dma-mapping.h>
12#include <linux/vmalloc.h>
13#include <linux/swiotlb.h>
14
15#include <xen/xen.h>
16#include <xen/interface/grant_table.h>
17#include <xen/interface/memory.h>
18#include <xen/page.h>
19#include <xen/swiotlb-xen.h>
20
21#include <asm/cacheflush.h>
22#include <asm/xen/hypercall.h>
23#include <asm/xen/interface.h>
24
25unsigned long xen_get_swiotlb_free_pages(unsigned int order)
26{
27	struct memblock_region *reg;
28	gfp_t flags = __GFP_NOWARN|__GFP_KSWAPD_RECLAIM;
29
30	for_each_memblock(memory, reg) {
31		if (reg->base < (phys_addr_t)0xffffffff) {
32			flags |= __GFP_DMA;
33			break;
34		}
35	}
36	return __get_free_pages(flags, order);
37}
38
39enum dma_cache_op {
40       DMA_UNMAP,
41       DMA_MAP,
42};
43static bool hypercall_cflush = false;
44
45/* functions called by SWIOTLB */
46
47static void dma_cache_maint(dma_addr_t handle, unsigned long offset,
48	size_t size, enum dma_data_direction dir, enum dma_cache_op op)
49{
50	struct gnttab_cache_flush cflush;
51	unsigned long xen_pfn;
52	size_t left = size;
53
54	xen_pfn = (handle >> XEN_PAGE_SHIFT) + offset / XEN_PAGE_SIZE;
55	offset %= XEN_PAGE_SIZE;
56
57	do {
58		size_t len = left;
59
60		/* buffers in highmem or foreign pages cannot cross page
61		 * boundaries */
62		if (len + offset > XEN_PAGE_SIZE)
63			len = XEN_PAGE_SIZE - offset;
64
65		cflush.op = 0;
66		cflush.a.dev_bus_addr = xen_pfn << XEN_PAGE_SHIFT;
67		cflush.offset = offset;
68		cflush.length = len;
69
70		if (op == DMA_UNMAP && dir != DMA_TO_DEVICE)
71			cflush.op = GNTTAB_CACHE_INVAL;
72		if (op == DMA_MAP) {
73			if (dir == DMA_FROM_DEVICE)
74				cflush.op = GNTTAB_CACHE_INVAL;
75			else
76				cflush.op = GNTTAB_CACHE_CLEAN;
77		}
78		if (cflush.op)
79			HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1);
80
81		offset = 0;
82		xen_pfn++;
83		left -= len;
84	} while (left);
85}
86
87static void __xen_dma_page_dev_to_cpu(struct device *hwdev, dma_addr_t handle,
88		size_t size, enum dma_data_direction dir)
89{
90	dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_UNMAP);
91}
92
93static void __xen_dma_page_cpu_to_dev(struct device *hwdev, dma_addr_t handle,
94		size_t size, enum dma_data_direction dir)
95{
96	dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_MAP);
97}
98
99void __xen_dma_map_page(struct device *hwdev, struct page *page,
100	     dma_addr_t dev_addr, unsigned long offset, size_t size,
101	     enum dma_data_direction dir, struct dma_attrs *attrs)
102{
103	if (is_device_dma_coherent(hwdev))
104		return;
105	if (dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
106		return;
107
108	__xen_dma_page_cpu_to_dev(hwdev, dev_addr, size, dir);
109}
110
111void __xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
112		size_t size, enum dma_data_direction dir,
113		struct dma_attrs *attrs)
114
115{
116	if (is_device_dma_coherent(hwdev))
117		return;
118	if (dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
119		return;
120
121	__xen_dma_page_dev_to_cpu(hwdev, handle, size, dir);
122}
123
124void __xen_dma_sync_single_for_cpu(struct device *hwdev,
125		dma_addr_t handle, size_t size, enum dma_data_direction dir)
126{
127	if (is_device_dma_coherent(hwdev))
128		return;
129	__xen_dma_page_dev_to_cpu(hwdev, handle, size, dir);
130}
131
132void __xen_dma_sync_single_for_device(struct device *hwdev,
133		dma_addr_t handle, size_t size, enum dma_data_direction dir)
134{
135	if (is_device_dma_coherent(hwdev))
136		return;
137	__xen_dma_page_cpu_to_dev(hwdev, handle, size, dir);
138}
139
140bool xen_arch_need_swiotlb(struct device *dev,
141			   phys_addr_t phys,
142			   dma_addr_t dev_addr)
143{
144	unsigned int xen_pfn = XEN_PFN_DOWN(phys);
145	unsigned int bfn = XEN_PFN_DOWN(dev_addr);
146
147	/*
148	 * The swiotlb buffer should be used if
149	 *	- Xen doesn't have the cache flush hypercall
150	 *	- The Linux page refers to foreign memory
151	 *	- The device doesn't support coherent DMA request
152	 *
153	 * The Linux page may be spanned acrros multiple Xen page, although
154	 * it's not possible to have a mix of local and foreign Xen page.
155	 * Furthermore, range_straddles_page_boundary is already checking
156	 * if buffer is physically contiguous in the host RAM.
157	 *
158	 * Therefore we only need to check the first Xen page to know if we
159	 * require a bounce buffer because the device doesn't support coherent
160	 * memory and we are not able to flush the cache.
161	 */
162	return (!hypercall_cflush && (xen_pfn != bfn) &&
163		!is_device_dma_coherent(dev));
164}
165
166int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
167				 unsigned int address_bits,
168				 dma_addr_t *dma_handle)
169{
170	if (!xen_initial_domain())
171		return -EINVAL;
172
173	/* we assume that dom0 is mapped 1:1 for now */
174	*dma_handle = pstart;
175	return 0;
176}
177EXPORT_SYMBOL_GPL(xen_create_contiguous_region);
178
179void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
180{
181	return;
182}
183EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region);
184
185struct dma_map_ops *xen_dma_ops;
186EXPORT_SYMBOL(xen_dma_ops);
187
188static struct dma_map_ops xen_swiotlb_dma_ops = {
189	.mapping_error = xen_swiotlb_dma_mapping_error,
190	.alloc = xen_swiotlb_alloc_coherent,
191	.free = xen_swiotlb_free_coherent,
192	.sync_single_for_cpu = xen_swiotlb_sync_single_for_cpu,
193	.sync_single_for_device = xen_swiotlb_sync_single_for_device,
194	.sync_sg_for_cpu = xen_swiotlb_sync_sg_for_cpu,
195	.sync_sg_for_device = xen_swiotlb_sync_sg_for_device,
196	.map_sg = xen_swiotlb_map_sg_attrs,
197	.unmap_sg = xen_swiotlb_unmap_sg_attrs,
198	.map_page = xen_swiotlb_map_page,
199	.unmap_page = xen_swiotlb_unmap_page,
200	.dma_supported = xen_swiotlb_dma_supported,
201	.set_dma_mask = xen_swiotlb_set_dma_mask,
202};
203
204int __init xen_mm_init(void)
205{
206	struct gnttab_cache_flush cflush;
207	if (!xen_initial_domain())
208		return 0;
209	xen_swiotlb_init(1, false);
210	xen_dma_ops = &xen_swiotlb_dma_ops;
211
212	cflush.op = 0;
213	cflush.a.dev_bus_addr = 0;
214	cflush.offset = 0;
215	cflush.length = 0;
216	if (HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1) != -ENOSYS)
217		hypercall_cflush = true;
218	return 0;
219}
220arch_initcall(xen_mm_init);
221