LXR linux/arch/x86/kernel/pci-swiotlb.c

   1// SPDX-License-Identifier: GPL-2.0
   2
   3#include <linux/pci.h>
   4#include <linux/cache.h>
   5#include <linux/init.h>
   6#include <linux/swiotlb.h>
   7#include <linux/memblock.h>
   8#include <linux/dma-direct.h>
   9#include <linux/mem_encrypt.h>
  10
  11#include <asm/iommu.h>
  12#include <asm/swiotlb.h>
  13#include <asm/dma.h>
  14#include <asm/xen/swiotlb-xen.h>
  15#include <asm/iommu_table.h>
  16
  17int swiotlb __read_mostly;
  18
  19/*
  20 * pci_swiotlb_detect_override - set swiotlb to 1 if necessary
  21 *
  22 * This returns non-zero if we are forced to use swiotlb (by the boot
  23 * option).
  24 */
  25int __init pci_swiotlb_detect_override(void)
  26{
  27        if (swiotlb_force == SWIOTLB_FORCE)
  28                swiotlb = 1;
  29
  30        return swiotlb;
  31}
  32IOMMU_INIT_FINISH(pci_swiotlb_detect_override,
  33                  pci_xen_swiotlb_detect,
  34                  pci_swiotlb_init,
  35                  pci_swiotlb_late_init);
  36
  37/*
  38 * If 4GB or more detected (and iommu=off not set) or if SME is active
  39 * then set swiotlb to 1 and return 1.
  40 */
  41int __init pci_swiotlb_detect_4gb(void)
  42{
  43        /* don't initialize swiotlb if iommu=off (no_iommu=1) */
  44        if (!no_iommu && max_possible_pfn > MAX_DMA32_PFN)
  45                swiotlb = 1;
  46
  47        /*
  48         * If SME is active then swiotlb will be set to 1 so that bounce
  49         * buffers are allocated and used for devices that do not support
  50         * the addressing range required for the encryption mask.
  51         */
  52        if (sme_active())
  53                swiotlb = 1;
  54
  55        return swiotlb;
  56}
  57IOMMU_INIT(pci_swiotlb_detect_4gb,
  58           pci_swiotlb_detect_override,
  59           pci_swiotlb_init,
  60           pci_swiotlb_late_init);
  61
  62void __init pci_swiotlb_init(void)
  63{
  64        if (swiotlb)
  65                swiotlb_init(0);
  66}
  67
  68void __init pci_swiotlb_late_init(void)
  69{
  70        /* An IOMMU turned us off. */
  71        if (!swiotlb)
  72                swiotlb_exit();
  73        else {
  74                printk(KERN_INFO "PCI-DMA: "
  75                       "Using software bounce buffering for IO (SWIOTLB)\n");
  76                swiotlb_print_info();
  77        }
  78}
  79