arch/x86/kernel/pci-swiotlb.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Glue code to lib/swiotlb.c */
   3
   4 #include <linux/pci.h>
   5 #include <linux/cache.h>
   6 #include <linux/init.h>
   7 #include <linux/swiotlb.h>
   8 #include <linux/bootmem.h>
   9 #include <linux/dma-mapping.h>
  10 #include <linux/mem_encrypt.h>
  11
  12 #include <asm/iommu.h>
  13 #include <asm/swiotlb.h>
  14 #include <asm/dma.h>
  15 #include <asm/xen/swiotlb-xen.h>
  16 #include <asm/iommu_table.h>
  17
  18 int swiotlb __read_mostly;
  19
  20 void *x86_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
  21                                         dma_addr_t *dma_handle, gfp_t flags,
  22                                         unsigned long attrs)
  23 {
  24         void *vaddr;
  25
  26         /*
  27          * Don't print a warning when the first allocation attempt fails.
  28          * swiotlb_alloc_coherent() will print a warning when the DMA
  29          * memory allocation ultimately failed.
  30          */
  31         flags |= __GFP_NOWARN;
  32
  33         vaddr = dma_generic_alloc_coherent(hwdev, size, dma_handle, flags,
  34                                            attrs);
  35         if (vaddr)
  36                 return vaddr;
  37
  38         return swiotlb_alloc_coherent(hwdev, size, dma_handle, flags);
  39 }
  40
  41 void x86_swiotlb_free_coherent(struct device *dev, size_t size,
  42                                       void *vaddr, dma_addr_t dma_addr,
  43                                       unsigned long attrs)
  44 {
  45         if (is_swiotlb_buffer(dma_to_phys(dev, dma_addr)))
  46                 swiotlb_free_coherent(dev, size, vaddr, dma_addr);
  47         else
  48                 dma_generic_free_coherent(dev, size, vaddr, dma_addr, attrs);
  49 }
  50
  51 static const struct dma_map_ops swiotlb_dma_ops = {
  52         .mapping_error = swiotlb_dma_mapping_error,
  53         .alloc = x86_swiotlb_alloc_coherent,
  54         .free = x86_swiotlb_free_coherent,
  55         .sync_single_for_cpu = swiotlb_sync_single_for_cpu,
  56         .sync_single_for_device = swiotlb_sync_single_for_device,
  57         .sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,
  58         .sync_sg_for_device = swiotlb_sync_sg_for_device,
  59         .map_sg = swiotlb_map_sg_attrs,
  60         .unmap_sg = swiotlb_unmap_sg_attrs,
  61         .map_page = swiotlb_map_page,
  62         .unmap_page = swiotlb_unmap_page,
  63         .dma_supported = NULL,
  64 };
  65
  66 /*
  67  * pci_swiotlb_detect_override - set swiotlb to 1 if necessary
  68  *
  69  * This returns non-zero if we are forced to use swiotlb (by the boot
  70  * option).
  71  */
  72 int __init pci_swiotlb_detect_override(void)
  73 {
  74         if (swiotlb_force == SWIOTLB_FORCE)
  75                 swiotlb = 1;
  76
  77         return swiotlb;
  78 }
  79 IOMMU_INIT_FINISH(pci_swiotlb_detect_override,
  80                   pci_xen_swiotlb_detect,
  81                   pci_swiotlb_init,
  82                   pci_swiotlb_late_init);
  83
  84 /*
  85  * If 4GB or more detected (and iommu=off not set) or if SME is active
  86  * then set swiotlb to 1 and return 1.
  87  */
  88 int __init pci_swiotlb_detect_4gb(void)
  89 {
  90         /* don't initialize swiotlb if iommu=off (no_iommu=1) */
  91 #ifdef CONFIG_X86_64
  92         if (!no_iommu && max_possible_pfn > MAX_DMA32_PFN)
  93                 swiotlb = 1;
  94 #endif
  95
  96         /*
  97          * If SME is active then swiotlb will be set to 1 so that bounce
  98          * buffers are allocated and used for devices that do not support
  99          * the addressing range required for the encryption mask.
 100          */
 101         if (sme_active())
 102                 swiotlb = 1;
 103
 104         return swiotlb;
 105 }
 106 IOMMU_INIT(pci_swiotlb_detect_4gb,
 107            pci_swiotlb_detect_override,
 108            pci_swiotlb_init,
 109            pci_swiotlb_late_init);
 110
 111 void __init pci_swiotlb_init(void)
 112 {
 113         if (swiotlb) {
 114                 swiotlb_init(0);
 115                 dma_ops = &swiotlb_dma_ops;
 116         }
 117 }
 118
 119 void __init pci_swiotlb_late_init(void)
 120 {
 121         /* An IOMMU turned us off. */
 122         if (!swiotlb)
 123                 swiotlb_free();
 124         else {
 125                 printk(KERN_INFO "PCI-DMA: "
 126                        "Using software bounce buffering for IO (SWIOTLB)\n");
 127                 swiotlb_print_info();
 128         }
 129 }