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1// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/cpu.h>
3#include <linux/dma-direct.h>
4#include <linux/dma-map-ops.h>
5#include <linux/gfp.h>
6#include <linux/highmem.h>
7#include <linux/export.h>
8#include <linux/memblock.h>
9#include <linux/of_address.h>
10#include <linux/slab.h>
11#include <linux/types.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/xen-ops.h>
20#include <xen/swiotlb-xen.h>
21
22#include <asm/cacheflush.h>
23#include <asm/xen/hypercall.h>
24#include <asm/xen/interface.h>
25
26static gfp_t xen_swiotlb_gfp(void)
27{
28 phys_addr_t base;
29 u64 i;
30
31 for_each_mem_range(i, &base, NULL) {
32 if (base < (phys_addr_t)0xffffffff) {
33 if (IS_ENABLED(CONFIG_ZONE_DMA32))
34 return __GFP_DMA32;
35 return __GFP_DMA;
36 }
37 }
38
39 return GFP_KERNEL;
40}
41
42static bool hypercall_cflush = false;
43
44/* buffers in highmem or foreign pages cannot cross page boundaries */
45static void dma_cache_maint(struct device *dev, dma_addr_t handle,
46 size_t size, u32 op)
47{
48 struct gnttab_cache_flush cflush;
49
50 cflush.offset = xen_offset_in_page(handle);
51 cflush.op = op;
52 handle &= XEN_PAGE_MASK;
53
54 do {
55 cflush.a.dev_bus_addr = dma_to_phys(dev, handle);
56
57 if (size + cflush.offset > XEN_PAGE_SIZE)
58 cflush.length = XEN_PAGE_SIZE - cflush.offset;
59 else
60 cflush.length = size;
61
62 HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1);
63
64 cflush.offset = 0;
65 handle += cflush.length;
66 size -= cflush.length;
67 } while (size);
68}
69
70/*
71 * Dom0 is mapped 1:1, and while the Linux page can span across multiple Xen
72 * pages, it is not possible for it to contain a mix of local and foreign Xen
73 * pages. Calling pfn_valid on a foreign mfn will always return false, so if
74 * pfn_valid returns true the pages is local and we can use the native
75 * dma-direct functions, otherwise we call the Xen specific version.
76 */
77void xen_dma_sync_for_cpu(struct device *dev, dma_addr_t handle,
78 size_t size, enum dma_data_direction dir)
79{
80 if (dir != DMA_TO_DEVICE)
81 dma_cache_maint(dev, handle, size, GNTTAB_CACHE_INVAL);
82}
83
84void xen_dma_sync_for_device(struct device *dev, dma_addr_t handle,
85 size_t size, enum dma_data_direction dir)
86{
87 if (dir == DMA_FROM_DEVICE)
88 dma_cache_maint(dev, handle, size, GNTTAB_CACHE_INVAL);
89 else
90 dma_cache_maint(dev, handle, size, GNTTAB_CACHE_CLEAN);
91}
92
93bool 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(dma_to_phys(dev, 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
119static int __init xen_mm_init(void)
120{
121 struct gnttab_cache_flush cflush;
122 int rc;
123
124 if (!xen_swiotlb_detect())
125 return 0;
126
127 /* we can work with the default swiotlb */
128 rc = swiotlb_init_late(swiotlb_size_or_default(),
129 xen_swiotlb_gfp(), NULL);
130 if (rc < 0)
131 return rc;
132
133 cflush.op = 0;
134 cflush.a.dev_bus_addr = 0;
135 cflush.offset = 0;
136 cflush.length = 0;
137 if (HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1) != -ENOSYS)
138 hypercall_cflush = true;
139 return 0;
140}
141arch_initcall(xen_mm_init);
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
24unsigned 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
41static bool hypercall_cflush = false;
42
43/* buffers in highmem or foreign pages cannot cross page boundaries */
44static 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 */
73void 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
82void 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
93bool 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
119int 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
131void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
132{
133 return;
134}
135
136int __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}
151arch_initcall(xen_mm_init);