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