arch/arm/xen/mm.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/cpu.h>
   3 #include <linux/dma-mapping.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
  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 enum dma_cache_op {
  42        DMA_UNMAP,
  43        DMA_MAP,
  44 };
  45 static bool hypercall_cflush = false;
  46
  47 /* functions called by SWIOTLB */
  48
  49 static void dma_cache_maint(dma_addr_t handle, unsigned long offset,
  50         size_t size, enum dma_data_direction dir, enum dma_cache_op op)
  51 {
  52         struct gnttab_cache_flush cflush;
  53         unsigned long xen_pfn;
  54         size_t left = size;
  55
  56         xen_pfn = (handle >> XEN_PAGE_SHIFT) + offset / XEN_PAGE_SIZE;
  57         offset %= XEN_PAGE_SIZE;
  58
  59         do {
  60                 size_t len = left;
  61
  62                 /* buffers in highmem or foreign pages cannot cross page
  63                  * boundaries */
  64                 if (len + offset > XEN_PAGE_SIZE)
  65                         len = XEN_PAGE_SIZE - offset;
  66
  67                 cflush.op = 0;
  68                 cflush.a.dev_bus_addr = xen_pfn << XEN_PAGE_SHIFT;
  69                 cflush.offset = offset;
  70                 cflush.length = len;
  71
  72                 if (op == DMA_UNMAP && dir != DMA_TO_DEVICE)
  73                         cflush.op = GNTTAB_CACHE_INVAL;
  74                 if (op == DMA_MAP) {
  75                         if (dir == DMA_FROM_DEVICE)
  76                                 cflush.op = GNTTAB_CACHE_INVAL;
  77                         else
  78                                 cflush.op = GNTTAB_CACHE_CLEAN;
  79                 }
  80                 if (cflush.op)
  81                         HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1);
  82
  83                 offset = 0;
  84                 xen_pfn++;
  85                 left -= len;
  86         } while (left);
  87 }
  88
  89 static void __xen_dma_page_dev_to_cpu(struct device *hwdev, dma_addr_t handle,
  90                 size_t size, enum dma_data_direction dir)
  91 {
  92         dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_UNMAP);
  93 }
  94
  95 static void __xen_dma_page_cpu_to_dev(struct device *hwdev, dma_addr_t handle,
  96                 size_t size, enum dma_data_direction dir)
  97 {
  98         dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_MAP);
  99 }
 100
 101 void __xen_dma_map_page(struct device *hwdev, struct page *page,
 102              dma_addr_t dev_addr, unsigned long offset, size_t size,
 103              enum dma_data_direction dir, unsigned long attrs)
 104 {
 105         if (is_device_dma_coherent(hwdev))
 106                 return;
 107         if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
 108                 return;
 109
 110         __xen_dma_page_cpu_to_dev(hwdev, dev_addr, size, dir);
 111 }
 112
 113 void __xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
 114                 size_t size, enum dma_data_direction dir,
 115                 unsigned long attrs)
 116
 117 {
 118         if (is_device_dma_coherent(hwdev))
 119                 return;
 120         if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
 121                 return;
 122
 123         __xen_dma_page_dev_to_cpu(hwdev, handle, size, dir);
 124 }
 125
 126 void __xen_dma_sync_single_for_cpu(struct device *hwdev,
 127                 dma_addr_t handle, size_t size, enum dma_data_direction dir)
 128 {
 129         if (is_device_dma_coherent(hwdev))
 130                 return;
 131         __xen_dma_page_dev_to_cpu(hwdev, handle, size, dir);
 132 }
 133
 134 void __xen_dma_sync_single_for_device(struct device *hwdev,
 135                 dma_addr_t handle, size_t size, enum dma_data_direction dir)
 136 {
 137         if (is_device_dma_coherent(hwdev))
 138                 return;
 139         __xen_dma_page_cpu_to_dev(hwdev, handle, size, dir);
 140 }
 141
 142 bool xen_arch_need_swiotlb(struct device *dev,
 143                            phys_addr_t phys,
 144                            dma_addr_t dev_addr)
 145 {
 146         unsigned int xen_pfn = XEN_PFN_DOWN(phys);
 147         unsigned int bfn = XEN_PFN_DOWN(dev_addr);
 148
 149         /*
 150          * The swiotlb buffer should be used if
 151          *      - Xen doesn't have the cache flush hypercall
 152          *      - The Linux page refers to foreign memory
 153          *      - The device doesn't support coherent DMA request
 154          *
 155          * The Linux page may be spanned acrros multiple Xen page, although
 156          * it's not possible to have a mix of local and foreign Xen page.
 157          * Furthermore, range_straddles_page_boundary is already checking
 158          * if buffer is physically contiguous in the host RAM.
 159          *
 160          * Therefore we only need to check the first Xen page to know if we
 161          * require a bounce buffer because the device doesn't support coherent
 162          * memory and we are not able to flush the cache.
 163          */
 164         return (!hypercall_cflush && (xen_pfn != bfn) &&
 165                 !is_device_dma_coherent(dev));
 166 }
 167
 168 int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
 169                                  unsigned int address_bits,
 170                                  dma_addr_t *dma_handle)
 171 {
 172         if (!xen_initial_domain())
 173                 return -EINVAL;
 174
 175         /* we assume that dom0 is mapped 1:1 for now */
 176         *dma_handle = pstart;
 177         return 0;
 178 }
 179 EXPORT_SYMBOL_GPL(xen_create_contiguous_region);
 180
 181 void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
 182 {
 183         return;
 184 }
 185 EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region);
 186
 187 const struct dma_map_ops *xen_dma_ops;
 188 EXPORT_SYMBOL(xen_dma_ops);
 189
 190 int __init xen_mm_init(void)
 191 {
 192         struct gnttab_cache_flush cflush;
 193         if (!xen_initial_domain())
 194                 return 0;
 195         xen_swiotlb_init(1, false);
 196         xen_dma_ops = &xen_swiotlb_dma_ops;
 197
 198         cflush.op = 0;
 199         cflush.a.dev_bus_addr = 0;
 200         cflush.offset = 0;
 201         cflush.length = 0;
 202         if (HYPERVISOR_grant_table_op(GNTTABOP_cache_flush, &cflush, 1) != -ENOSYS)
 203                 hypercall_cflush = true;
 204         return 0;
 205 }
 206 arch_initcall(xen_mm_init);