kernel/dma/direct.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * DMA operations that map physical memory directly without using an IOMMU or
   4  * flushing caches.
   5  */
   6 #include <linux/export.h>
   7 #include <linux/mm.h>
   8 #include <linux/dma-direct.h>
   9 #include <linux/scatterlist.h>
  10 #include <linux/dma-contiguous.h>
  11 #include <linux/pfn.h>
  12 #include <linux/set_memory.h>
  13
  14 #define DIRECT_MAPPING_ERROR            0
  15
  16 /*
  17  * Most architectures use ZONE_DMA for the first 16 Megabytes, but
  18  * some use it for entirely different regions:
  19  */
  20 #ifndef ARCH_ZONE_DMA_BITS
  21 #define ARCH_ZONE_DMA_BITS 24
  22 #endif
  23
  24 /*
  25  * For AMD SEV all DMA must be to unencrypted addresses.
  26  */
  27 static inline bool force_dma_unencrypted(void)
  28 {
  29         return sev_active();
  30 }
  31
  32 static bool
  33 check_addr(struct device *dev, dma_addr_t dma_addr, size_t size,
  34                 const char *caller)
  35 {
  36         if (unlikely(dev && !dma_capable(dev, dma_addr, size))) {
  37                 if (!dev->dma_mask) {
  38                         dev_err(dev,
  39                                 "%s: call on device without dma_mask\n",
  40                                 caller);
  41                         return false;
  42                 }
  43
  44                 if (*dev->dma_mask >= DMA_BIT_MASK(32)) {
  45                         dev_err(dev,
  46                                 "%s: overflow %pad+%zu of device mask %llx\n",
  47                                 caller, &dma_addr, size, *dev->dma_mask);
  48                 }
  49                 return false;
  50         }
  51         return true;
  52 }
  53
  54 static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
  55 {
  56         dma_addr_t addr = force_dma_unencrypted() ?
  57                 __phys_to_dma(dev, phys) : phys_to_dma(dev, phys);
  58         return addr + size - 1 <= dev->coherent_dma_mask;
  59 }
  60
  61 void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
  62                 gfp_t gfp, unsigned long attrs)
  63 {
  64         unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
  65         int page_order = get_order(size);
  66         struct page *page = NULL;
  67         void *ret;
  68
  69         /* we always manually zero the memory once we are done: */
  70         gfp &= ~__GFP_ZERO;
  71
  72         /* GFP_DMA32 and GFP_DMA are no ops without the corresponding zones: */
  73         if (dev->coherent_dma_mask <= DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))
  74                 gfp |= GFP_DMA;
  75         if (dev->coherent_dma_mask <= DMA_BIT_MASK(32) && !(gfp & GFP_DMA))
  76                 gfp |= GFP_DMA32;
  77
  78 again:
  79         /* CMA can be used only in the context which permits sleeping */
  80         if (gfpflags_allow_blocking(gfp)) {
  81                 page = dma_alloc_from_contiguous(dev, count, page_order,
  82                                                  gfp & __GFP_NOWARN);
  83                 if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
  84                         dma_release_from_contiguous(dev, page, count);
  85                         page = NULL;
  86                 }
  87         }
  88         if (!page)
  89                 page = alloc_pages_node(dev_to_node(dev), gfp, page_order);
  90
  91         if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
  92                 __free_pages(page, page_order);
  93                 page = NULL;
  94
  95                 if (IS_ENABLED(CONFIG_ZONE_DMA32) &&
  96                     dev->coherent_dma_mask < DMA_BIT_MASK(64) &&
  97                     !(gfp & (GFP_DMA32 | GFP_DMA))) {
  98                         gfp |= GFP_DMA32;
  99                         goto again;
 100                 }
 101
 102                 if (IS_ENABLED(CONFIG_ZONE_DMA) &&
 103                     dev->coherent_dma_mask < DMA_BIT_MASK(32) &&
 104                     !(gfp & GFP_DMA)) {
 105                         gfp = (gfp & ~GFP_DMA32) | GFP_DMA;
 106                         goto again;
 107                 }
 108         }
 109
 110         if (!page)
 111                 return NULL;
 112         ret = page_address(page);
 113         if (force_dma_unencrypted()) {
 114                 set_memory_decrypted((unsigned long)ret, 1 << page_order);
 115                 *dma_handle = __phys_to_dma(dev, page_to_phys(page));
 116         } else {
 117                 *dma_handle = phys_to_dma(dev, page_to_phys(page));
 118         }
 119         memset(ret, 0, size);
 120         return ret;
 121 }
 122
 123 /*
 124  * NOTE: this function must never look at the dma_addr argument, because we want
 125  * to be able to use it as a helper for iommu implementations as well.
 126  */
 127 void dma_direct_free(struct device *dev, size_t size, void *cpu_addr,
 128                 dma_addr_t dma_addr, unsigned long attrs)
 129 {
 130         unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 131         unsigned int page_order = get_order(size);
 132
 133         if (force_dma_unencrypted())
 134                 set_memory_encrypted((unsigned long)cpu_addr, 1 << page_order);
 135         if (!dma_release_from_contiguous(dev, virt_to_page(cpu_addr), count))
 136                 free_pages((unsigned long)cpu_addr, page_order);
 137 }
 138
 139 dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
 140                 unsigned long offset, size_t size, enum dma_data_direction dir,
 141                 unsigned long attrs)
 142 {
 143         dma_addr_t dma_addr = phys_to_dma(dev, page_to_phys(page)) + offset;
 144
 145         if (!check_addr(dev, dma_addr, size, __func__))
 146                 return DIRECT_MAPPING_ERROR;
 147         return dma_addr;
 148 }
 149
 150 int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
 151                 enum dma_data_direction dir, unsigned long attrs)
 152 {
 153         int i;
 154         struct scatterlist *sg;
 155
 156         for_each_sg(sgl, sg, nents, i) {
 157                 BUG_ON(!sg_page(sg));
 158
 159                 sg_dma_address(sg) = phys_to_dma(dev, sg_phys(sg));
 160                 if (!check_addr(dev, sg_dma_address(sg), sg->length, __func__))
 161                         return 0;
 162                 sg_dma_len(sg) = sg->length;
 163         }
 164
 165         return nents;
 166 }
 167
 168 int dma_direct_supported(struct device *dev, u64 mask)
 169 {
 170 #ifdef CONFIG_ZONE_DMA
 171         /*
 172          * This check needs to be against the actual bit mask value, so
 173          * use __phys_to_dma() here so that the SME encryption mask isn't
 174          * part of the check.
 175          */
 176         if (mask < __phys_to_dma(dev, DMA_BIT_MASK(ARCH_ZONE_DMA_BITS)))
 177                 return 0;
 178 #else
 179         /*
 180          * Because 32-bit DMA masks are so common we expect every architecture
 181          * to be able to satisfy them - either by not supporting more physical
 182          * memory, or by providing a ZONE_DMA32.  If neither is the case, the
 183          * architecture needs to use an IOMMU instead of the direct mapping.
 184          *
 185          * This check needs to be against the actual bit mask value, so
 186          * use __phys_to_dma() here so that the SME encryption mask isn't
 187          * part of the check.
 188          */
 189         if (mask < __phys_to_dma(dev, DMA_BIT_MASK(32)))
 190                 return 0;
 191 #endif
 192         /*
 193          * Upstream PCI/PCIe bridges or SoC interconnects may not carry
 194          * as many DMA address bits as the device itself supports.
 195          */
 196         if (dev->bus_dma_mask && mask > dev->bus_dma_mask)
 197                 return 0;
 198         return 1;
 199 }
 200
 201 int dma_direct_mapping_error(struct device *dev, dma_addr_t dma_addr)
 202 {
 203         return dma_addr == DIRECT_MAPPING_ERROR;
 204 }
 205
 206 const struct dma_map_ops dma_direct_ops = {
 207         .alloc                  = dma_direct_alloc,
 208         .free                   = dma_direct_free,
 209         .map_page               = dma_direct_map_page,
 210         .map_sg                 = dma_direct_map_sg,
 211         .dma_supported          = dma_direct_supported,
 212         .mapping_error          = dma_direct_mapping_error,
 213 };
 214 EXPORT_SYMBOL(dma_direct_ops);