LXR linux/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
  18int swiotlb __read_mostly;
  19
  20void *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
  41void 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
  51static 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 */
  72int __init pci_swiotlb_detect_override(void)
  73{
  74        if (swiotlb_force == SWIOTLB_FORCE)
  75                swiotlb = 1;
  76
  77        return swiotlb;
  78}
  79IOMMU_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 */
  88int __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}
 106IOMMU_INIT(pci_swiotlb_detect_4gb,
 107           pci_swiotlb_detect_override,
 108           pci_swiotlb_init,
 109           pci_swiotlb_late_init);
 110
 111void __init pci_swiotlb_init(void)
 112{
 113        if (swiotlb) {
 114                swiotlb_init(0);
 115                dma_ops = &swiotlb_dma_ops;
 116        }
 117}
 118
 119void __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}
 130