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>
10 #include <asm/proto.h>
12 #include <asm/iommu.h>
14 #include <asm/calgary.h>
15 #include <asm/x86_init.h>
16 #include <asm/iommu_table.h>
18 static bool disable_dac_quirk __read_mostly;
20 const struct dma_map_ops *dma_ops = &dma_direct_ops;
21 EXPORT_SYMBOL(dma_ops);
23 #ifdef CONFIG_IOMMU_DEBUG
24 int panic_on_overflow __read_mostly = 1;
25 int force_iommu __read_mostly = 1;
27 int panic_on_overflow __read_mostly = 0;
28 int force_iommu __read_mostly = 0;
31 int iommu_merge __read_mostly = 0;
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;
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.
44 int iommu_pass_through __read_mostly;
46 extern struct iommu_table_entry __iommu_table[], __iommu_table_end[];
48 /* Dummy device used for NULL arguments (normally ISA). */
49 struct device x86_dma_fallback_dev = {
50 .init_name = "fallback device",
51 .coherent_dma_mask = ISA_DMA_BIT_MASK,
52 .dma_mask = &x86_dma_fallback_dev.coherent_dma_mask,
54 EXPORT_SYMBOL(x86_dma_fallback_dev);
56 void __init pci_iommu_alloc(void)
58 struct iommu_table_entry *p;
60 sort_iommu_table(__iommu_table, __iommu_table_end);
61 check_iommu_entries(__iommu_table, __iommu_table_end);
63 for (p = __iommu_table; p < __iommu_table_end; p++) {
64 if (p && p->detect && p->detect() > 0) {
65 p->flags |= IOMMU_DETECTED;
68 if (p->flags & IOMMU_FINISH_IF_DETECTED)
74 bool arch_dma_alloc_attrs(struct device **dev)
77 *dev = &x86_dma_fallback_dev;
79 if (!is_device_dma_capable(*dev))
84 EXPORT_SYMBOL(arch_dma_alloc_attrs);
87 * See <Documentation/x86/x86_64/boot-options.txt> for the iommu kernel
88 * parameter documentation.
90 static __init int iommu_setup(char *p)
98 if (!strncmp(p, "off", 3))
100 /* gart_parse_options has more force support */
101 if (!strncmp(p, "force", 5))
103 if (!strncmp(p, "noforce", 7)) {
108 if (!strncmp(p, "biomerge", 8)) {
112 if (!strncmp(p, "panic", 5))
113 panic_on_overflow = 1;
114 if (!strncmp(p, "nopanic", 7))
115 panic_on_overflow = 0;
116 if (!strncmp(p, "merge", 5)) {
120 if (!strncmp(p, "nomerge", 7))
122 if (!strncmp(p, "forcesac", 8))
123 pr_warn("forcesac option ignored.\n");
124 if (!strncmp(p, "allowdac", 8))
125 pr_warn("allowdac option ignored.\n");
126 if (!strncmp(p, "nodac", 5))
127 pr_warn("nodac option ignored.\n");
128 if (!strncmp(p, "usedac", 6)) {
129 disable_dac_quirk = true;
132 #ifdef CONFIG_SWIOTLB
133 if (!strncmp(p, "soft", 4))
136 if (!strncmp(p, "pt", 2))
137 iommu_pass_through = 1;
139 gart_parse_options(p);
141 #ifdef CONFIG_CALGARY_IOMMU
142 if (!strncmp(p, "calgary", 7))
144 #endif /* CONFIG_CALGARY_IOMMU */
146 p += strcspn(p, ",");
152 early_param("iommu", iommu_setup);
154 static int __init pci_iommu_init(void)
156 struct iommu_table_entry *p;
159 dma_debug_add_bus(&pci_bus_type);
161 x86_init.iommu.iommu_init();
163 for (p = __iommu_table; p < __iommu_table_end; p++) {
164 if (p && (p->flags & IOMMU_DETECTED) && p->late_init)
170 /* Must execute after PCI subsystem */
171 rootfs_initcall(pci_iommu_init);
174 /* Many VIA bridges seem to corrupt data for DAC. Disable it here */
176 static int via_no_dac_cb(struct pci_dev *pdev, void *data)
178 pdev->dev.dma_32bit_limit = true;
182 static void via_no_dac(struct pci_dev *dev)
184 if (!disable_dac_quirk) {
185 dev_info(&dev->dev, "disabling DAC on VIA PCI bridge\n");
186 pci_walk_bus(dev->subordinate, via_no_dac_cb, NULL);
189 DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID,
190 PCI_CLASS_BRIDGE_PCI, 8, via_no_dac);