arch/x86/kernel/pci-dma.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/dma-direct.h>
   3 #include <linux/dma-debug.h>
   4 #include <linux/dmar.h>
   5 #include <linux/export.h>
   6 #include <linux/bootmem.h>
   7 #include <linux/gfp.h>
   8 #include <linux/pci.h>
   9
  10 #include <asm/proto.h>
  11 #include <asm/dma.h>
  12 #include <asm/iommu.h>
  13 #include <asm/gart.h>
  14 #include <asm/calgary.h>
  15 #include <asm/x86_init.h>
  16 #include <asm/iommu_table.h>
  17
  18 static bool disable_dac_quirk __read_mostly;
  19
  20 const struct dma_map_ops *dma_ops = &dma_direct_ops;
  21 EXPORT_SYMBOL(dma_ops);
  22
  23 #ifdef CONFIG_IOMMU_DEBUG
  24 int panic_on_overflow __read_mostly = 1;
  25 int force_iommu __read_mostly = 1;
  26 #else
  27 int panic_on_overflow __read_mostly = 0;
  28 int force_iommu __read_mostly = 0;
  29 #endif
  30
  31 int iommu_merge __read_mostly = 0;
  32
  33 int no_iommu __read_mostly;
  34 /* Set this to 1 if there is a HW IOMMU in the system */
  35 int iommu_detected __read_mostly = 0;
  36
  37 /*
  38  * This variable becomes 1 if iommu=pt is passed on the kernel command line.
  39  * If this variable is 1, IOMMU implementations do no DMA translation for
  40  * devices and allow every device to access to whole physical memory. This is
  41  * useful if a user wants to use an IOMMU only for KVM device assignment to
  42  * guests and not for driver dma translation.
  43  * It is also possible to disable by default in kernel config, and enable with
  44  * iommu=nopt at boot time.
  45  */
  46 #ifdef CONFIG_IOMMU_DEFAULT_PASSTHROUGH
  47 int iommu_pass_through __read_mostly = 1;
  48 #else
  49 int iommu_pass_through __read_mostly;
  50 #endif
  51
  52 extern struct iommu_table_entry __iommu_table[], __iommu_table_end[];
  53
  54 /* Dummy device used for NULL arguments (normally ISA). */
  55 struct device x86_dma_fallback_dev = {
  56         .init_name = "fallback device",
  57         .coherent_dma_mask = ISA_DMA_BIT_MASK,
  58         .dma_mask = &x86_dma_fallback_dev.coherent_dma_mask,
  59 };
  60 EXPORT_SYMBOL(x86_dma_fallback_dev);
  61
  62 void __init pci_iommu_alloc(void)
  63 {
  64         struct iommu_table_entry *p;
  65
  66         sort_iommu_table(__iommu_table, __iommu_table_end);
  67         check_iommu_entries(__iommu_table, __iommu_table_end);
  68
  69         for (p = __iommu_table; p < __iommu_table_end; p++) {
  70                 if (p && p->detect && p->detect() > 0) {
  71                         p->flags |= IOMMU_DETECTED;
  72                         if (p->early_init)
  73                                 p->early_init();
  74                         if (p->flags & IOMMU_FINISH_IF_DETECTED)
  75                                 break;
  76                 }
  77         }
  78 }
  79
  80 bool arch_dma_alloc_attrs(struct device **dev)
  81 {
  82         if (!*dev)
  83                 *dev = &x86_dma_fallback_dev;
  84
  85         if (!is_device_dma_capable(*dev))
  86                 return false;
  87         return true;
  88
  89 }
  90 EXPORT_SYMBOL(arch_dma_alloc_attrs);
  91
  92 /*
  93  * See <Documentation/x86/x86_64/boot-options.txt> for the iommu kernel
  94  * parameter documentation.
  95  */
  96 static __init int iommu_setup(char *p)
  97 {
  98         iommu_merge = 1;
  99
 100         if (!p)
 101                 return -EINVAL;
 102
 103         while (*p) {
 104                 if (!strncmp(p, "off", 3))
 105                         no_iommu = 1;
 106                 /* gart_parse_options has more force support */
 107                 if (!strncmp(p, "force", 5))
 108                         force_iommu = 1;
 109                 if (!strncmp(p, "noforce", 7)) {
 110                         iommu_merge = 0;
 111                         force_iommu = 0;
 112                 }
 113
 114                 if (!strncmp(p, "biomerge", 8)) {
 115                         iommu_merge = 1;
 116                         force_iommu = 1;
 117                 }
 118                 if (!strncmp(p, "panic", 5))
 119                         panic_on_overflow = 1;
 120                 if (!strncmp(p, "nopanic", 7))
 121                         panic_on_overflow = 0;
 122                 if (!strncmp(p, "merge", 5)) {
 123                         iommu_merge = 1;
 124                         force_iommu = 1;
 125                 }
 126                 if (!strncmp(p, "nomerge", 7))
 127                         iommu_merge = 0;
 128                 if (!strncmp(p, "forcesac", 8))
 129                         pr_warn("forcesac option ignored.\n");
 130                 if (!strncmp(p, "allowdac", 8))
 131                         pr_warn("allowdac option ignored.\n");
 132                 if (!strncmp(p, "nodac", 5))
 133                         pr_warn("nodac option ignored.\n");
 134                 if (!strncmp(p, "usedac", 6)) {
 135                         disable_dac_quirk = true;
 136                         return 1;
 137                 }
 138 #ifdef CONFIG_SWIOTLB
 139                 if (!strncmp(p, "soft", 4))
 140                         swiotlb = 1;
 141 #endif
 142                 if (!strncmp(p, "pt", 2))
 143                         iommu_pass_through = 1;
 144                 if (!strncmp(p, "nopt", 4))
 145                         iommu_pass_through = 0;
 146
 147                 gart_parse_options(p);
 148
 149 #ifdef CONFIG_CALGARY_IOMMU
 150                 if (!strncmp(p, "calgary", 7))
 151                         use_calgary = 1;
 152 #endif /* CONFIG_CALGARY_IOMMU */
 153
 154                 p += strcspn(p, ",");
 155                 if (*p == ',')
 156                         ++p;
 157         }
 158         return 0;
 159 }
 160 early_param("iommu", iommu_setup);
 161
 162 static int __init pci_iommu_init(void)
 163 {
 164         struct iommu_table_entry *p;
 165
 166         x86_init.iommu.iommu_init();
 167
 168         for (p = __iommu_table; p < __iommu_table_end; p++) {
 169                 if (p && (p->flags & IOMMU_DETECTED) && p->late_init)
 170                         p->late_init();
 171         }
 172
 173         return 0;
 174 }
 175 /* Must execute after PCI subsystem */
 176 rootfs_initcall(pci_iommu_init);
 177
 178 #ifdef CONFIG_PCI
 179 /* Many VIA bridges seem to corrupt data for DAC. Disable it here */
 180
 181 static int via_no_dac_cb(struct pci_dev *pdev, void *data)
 182 {
 183         pdev->dev.bus_dma_mask = DMA_BIT_MASK(32);
 184         return 0;
 185 }
 186
 187 static void via_no_dac(struct pci_dev *dev)
 188 {
 189         if (!disable_dac_quirk) {
 190                 dev_info(&dev->dev, "disabling DAC on VIA PCI bridge\n");
 191                 pci_walk_bus(dev->subordinate, via_no_dac_cb, NULL);
 192         }
 193 }
 194 DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID,
 195                                 PCI_CLASS_BRIDGE_PCI, 8, via_no_dac);
 196 #endif