arch/x86/kernel/pci-dma.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/dma-map-ops.h>
   3 #include <linux/dma-direct.h>
   4 #include <linux/iommu.h>
   5 #include <linux/dmar.h>
   6 #include <linux/export.h>
   7 #include <linux/memblock.h>
   8 #include <linux/gfp.h>
   9 #include <linux/pci.h>
  10 #include <linux/amd-iommu.h>
  11
  12 #include <asm/proto.h>
  13 #include <asm/dma.h>
  14 #include <asm/iommu.h>
  15 #include <asm/gart.h>
  16 #include <asm/x86_init.h>
  17
  18 #include <xen/xen.h>
  19 #include <xen/swiotlb-xen.h>
  20
  21 static bool disable_dac_quirk __read_mostly;
  22
  23 const struct dma_map_ops *dma_ops;
  24 EXPORT_SYMBOL(dma_ops);
  25
  26 #ifdef CONFIG_IOMMU_DEBUG
  27 int panic_on_overflow __read_mostly = 1;
  28 int force_iommu __read_mostly = 1;
  29 #else
  30 int panic_on_overflow __read_mostly = 0;
  31 int force_iommu __read_mostly = 0;
  32 #endif
  33
  34 int iommu_merge __read_mostly = 0;
  35
  36 int no_iommu __read_mostly;
  37 /* Set this to 1 if there is a HW IOMMU in the system */
  38 int iommu_detected __read_mostly = 0;
  39
  40 #ifdef CONFIG_SWIOTLB
  41 bool x86_swiotlb_enable;
  42 static unsigned int x86_swiotlb_flags;
  43
  44 static void __init pci_swiotlb_detect(void)
  45 {
  46         /* don't initialize swiotlb if iommu=off (no_iommu=1) */
  47         if (!no_iommu && max_possible_pfn > MAX_DMA32_PFN)
  48                 x86_swiotlb_enable = true;
  49
  50         /*
  51          * Set swiotlb to 1 so that bounce buffers are allocated and used for
  52          * devices that can't support DMA to encrypted memory.
  53          */
  54         if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
  55                 x86_swiotlb_enable = true;
  56
  57         /*
  58          * Guest with guest memory encryption currently perform all DMA through
  59          * bounce buffers as the hypervisor can't access arbitrary VM memory
  60          * that is not explicitly shared with it.
  61          */
  62         if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)) {
  63                 x86_swiotlb_enable = true;
  64                 x86_swiotlb_flags |= SWIOTLB_FORCE;
  65         }
  66 }
  67 #else
  68 static inline void __init pci_swiotlb_detect(void)
  69 {
  70 }
  71 #define x86_swiotlb_flags 0
  72 #endif /* CONFIG_SWIOTLB */
  73
  74 #ifdef CONFIG_SWIOTLB_XEN
  75 static bool xen_swiotlb_enabled(void)
  76 {
  77         return xen_initial_domain() || x86_swiotlb_enable ||
  78                 (IS_ENABLED(CONFIG_XEN_PCIDEV_FRONTEND) && xen_pv_pci_possible);
  79 }
  80
  81 static void __init pci_xen_swiotlb_init(void)
  82 {
  83         if (!xen_swiotlb_enabled())
  84                 return;
  85         x86_swiotlb_enable = true;
  86         x86_swiotlb_flags |= SWIOTLB_ANY;
  87         swiotlb_init_remap(true, x86_swiotlb_flags, xen_swiotlb_fixup);
  88         dma_ops = &xen_swiotlb_dma_ops;
  89         if (IS_ENABLED(CONFIG_PCI))
  90                 pci_request_acs();
  91 }
  92 #else
  93 static inline void __init pci_xen_swiotlb_init(void)
  94 {
  95 }
  96 #endif /* CONFIG_SWIOTLB_XEN */
  97
  98 void __init pci_iommu_alloc(void)
  99 {
 100         if (xen_pv_domain()) {
 101                 pci_xen_swiotlb_init();
 102                 return;
 103         }
 104         pci_swiotlb_detect();
 105         gart_iommu_hole_init();
 106         amd_iommu_detect();
 107         detect_intel_iommu();
 108         swiotlb_init(x86_swiotlb_enable, x86_swiotlb_flags);
 109 }
 110
 111 /*
 112  * See <Documentation/arch/x86/x86_64/boot-options.rst> for the iommu kernel
 113  * parameter documentation.
 114  */
 115 static __init int iommu_setup(char *p)
 116 {
 117         iommu_merge = 1;
 118
 119         if (!p)
 120                 return -EINVAL;
 121
 122         while (*p) {
 123                 if (!strncmp(p, "off", 3))
 124                         no_iommu = 1;
 125                 /* gart_parse_options has more force support */
 126                 if (!strncmp(p, "force", 5))
 127                         force_iommu = 1;
 128                 if (!strncmp(p, "noforce", 7)) {
 129                         iommu_merge = 0;
 130                         force_iommu = 0;
 131                 }
 132
 133                 if (!strncmp(p, "biomerge", 8)) {
 134                         iommu_merge = 1;
 135                         force_iommu = 1;
 136                 }
 137                 if (!strncmp(p, "panic", 5))
 138                         panic_on_overflow = 1;
 139                 if (!strncmp(p, "nopanic", 7))
 140                         panic_on_overflow = 0;
 141                 if (!strncmp(p, "merge", 5)) {
 142                         iommu_merge = 1;
 143                         force_iommu = 1;
 144                 }
 145                 if (!strncmp(p, "nomerge", 7))
 146                         iommu_merge = 0;
 147                 if (!strncmp(p, "forcesac", 8))
 148                         pr_warn("forcesac option ignored.\n");
 149                 if (!strncmp(p, "allowdac", 8))
 150                         pr_warn("allowdac option ignored.\n");
 151                 if (!strncmp(p, "nodac", 5))
 152                         pr_warn("nodac option ignored.\n");
 153                 if (!strncmp(p, "usedac", 6)) {
 154                         disable_dac_quirk = true;
 155                         return 1;
 156                 }
 157 #ifdef CONFIG_SWIOTLB
 158                 if (!strncmp(p, "soft", 4))
 159                         x86_swiotlb_enable = true;
 160 #endif
 161                 if (!strncmp(p, "pt", 2))
 162                         iommu_set_default_passthrough(true);
 163                 if (!strncmp(p, "nopt", 4))
 164                         iommu_set_default_translated(true);
 165
 166                 gart_parse_options(p);
 167
 168                 p += strcspn(p, ",");
 169                 if (*p == ',')
 170                         ++p;
 171         }
 172         return 0;
 173 }
 174 early_param("iommu", iommu_setup);
 175
 176 static int __init pci_iommu_init(void)
 177 {
 178         x86_init.iommu.iommu_init();
 179
 180 #ifdef CONFIG_SWIOTLB
 181         /* An IOMMU turned us off. */
 182         if (x86_swiotlb_enable) {
 183                 pr_info("PCI-DMA: Using software bounce buffering for IO (SWIOTLB)\n");
 184                 swiotlb_print_info();
 185         } else {
 186                 swiotlb_exit();
 187         }
 188 #endif
 189
 190         return 0;
 191 }
 192 /* Must execute after PCI subsystem */
 193 rootfs_initcall(pci_iommu_init);
 194
 195 #ifdef CONFIG_PCI
 196 /* Many VIA bridges seem to corrupt data for DAC. Disable it here */
 197
 198 static int via_no_dac_cb(struct pci_dev *pdev, void *data)
 199 {
 200         pdev->dev.bus_dma_limit = DMA_BIT_MASK(32);
 201         return 0;
 202 }
 203
 204 static void via_no_dac(struct pci_dev *dev)
 205 {
 206         if (!disable_dac_quirk) {
 207                 dev_info(&dev->dev, "disabling DAC on VIA PCI bridge\n");
 208                 pci_walk_bus(dev->subordinate, via_no_dac_cb, NULL);
 209         }
 210 }
 211 DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID,
 212                                 PCI_CLASS_BRIDGE_PCI, 8, via_no_dac);
 213 #endif