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 int forbid_dac __read_mostly;
20 const struct dma_map_ops *dma_ops = &dma_direct_ops;
21 EXPORT_SYMBOL(dma_ops);
23 static int iommu_sac_force __read_mostly;
25 #ifdef CONFIG_IOMMU_DEBUG
26 int panic_on_overflow __read_mostly = 1;
27 int force_iommu __read_mostly = 1;
29 int panic_on_overflow __read_mostly = 0;
30 int force_iommu __read_mostly = 0;
33 int iommu_merge __read_mostly = 0;
35 int no_iommu __read_mostly;
36 /* Set this to 1 if there is a HW IOMMU in the system */
37 int iommu_detected __read_mostly = 0;
40 * This variable becomes 1 if iommu=pt is passed on the kernel command line.
41 * If this variable is 1, IOMMU implementations do no DMA translation for
42 * devices and allow every device to access to whole physical memory. This is
43 * useful if a user wants to use an IOMMU only for KVM device assignment to
44 * guests and not for driver dma translation.
46 int iommu_pass_through __read_mostly;
48 extern struct iommu_table_entry __iommu_table[], __iommu_table_end[];
50 /* Dummy device used for NULL arguments (normally ISA). */
51 struct device x86_dma_fallback_dev = {
52 .init_name = "fallback device",
53 .coherent_dma_mask = ISA_DMA_BIT_MASK,
54 .dma_mask = &x86_dma_fallback_dev.coherent_dma_mask,
56 EXPORT_SYMBOL(x86_dma_fallback_dev);
58 /* Number of entries preallocated for DMA-API debugging */
59 #define PREALLOC_DMA_DEBUG_ENTRIES 65536
61 void __init pci_iommu_alloc(void)
63 struct iommu_table_entry *p;
65 sort_iommu_table(__iommu_table, __iommu_table_end);
66 check_iommu_entries(__iommu_table, __iommu_table_end);
68 for (p = __iommu_table; p < __iommu_table_end; p++) {
69 if (p && p->detect && p->detect() > 0) {
70 p->flags |= IOMMU_DETECTED;
73 if (p->flags & IOMMU_FINISH_IF_DETECTED)
79 bool arch_dma_alloc_attrs(struct device **dev, gfp_t *gfp)
82 *dev = &x86_dma_fallback_dev;
84 if (!is_device_dma_capable(*dev))
89 EXPORT_SYMBOL(arch_dma_alloc_attrs);
92 * See <Documentation/x86/x86_64/boot-options.txt> for the iommu kernel
93 * parameter documentation.
95 static __init int iommu_setup(char *p)
103 if (!strncmp(p, "off", 3))
105 /* gart_parse_options has more force support */
106 if (!strncmp(p, "force", 5))
108 if (!strncmp(p, "noforce", 7)) {
113 if (!strncmp(p, "biomerge", 8)) {
117 if (!strncmp(p, "panic", 5))
118 panic_on_overflow = 1;
119 if (!strncmp(p, "nopanic", 7))
120 panic_on_overflow = 0;
121 if (!strncmp(p, "merge", 5)) {
125 if (!strncmp(p, "nomerge", 7))
127 if (!strncmp(p, "forcesac", 8))
129 if (!strncmp(p, "allowdac", 8))
131 if (!strncmp(p, "nodac", 5))
133 if (!strncmp(p, "usedac", 6)) {
137 #ifdef CONFIG_SWIOTLB
138 if (!strncmp(p, "soft", 4))
141 if (!strncmp(p, "pt", 2))
142 iommu_pass_through = 1;
144 gart_parse_options(p);
146 #ifdef CONFIG_CALGARY_IOMMU
147 if (!strncmp(p, "calgary", 7))
149 #endif /* CONFIG_CALGARY_IOMMU */
151 p += strcspn(p, ",");
157 early_param("iommu", iommu_setup);
159 int arch_dma_supported(struct device *dev, u64 mask)
162 if (mask > 0xffffffff && forbid_dac > 0) {
163 dev_info(dev, "PCI: Disallowing DAC for device\n");
168 /* Tell the device to use SAC when IOMMU force is on. This
169 allows the driver to use cheaper accesses in some cases.
171 Problem with this is that if we overflow the IOMMU area and
172 return DAC as fallback address the device may not handle it
175 As a special case some controllers have a 39bit address
176 mode that is as efficient as 32bit (aic79xx). Don't force
177 SAC for these. Assume all masks <= 40 bits are of this
178 type. Normally this doesn't make any difference, but gives
179 more gentle handling of IOMMU overflow. */
180 if (iommu_sac_force && (mask >= DMA_BIT_MASK(40))) {
181 dev_info(dev, "Force SAC with mask %Lx\n", mask);
187 EXPORT_SYMBOL(arch_dma_supported);
189 static int __init pci_iommu_init(void)
191 struct iommu_table_entry *p;
192 dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
195 dma_debug_add_bus(&pci_bus_type);
197 x86_init.iommu.iommu_init();
199 for (p = __iommu_table; p < __iommu_table_end; p++) {
200 if (p && (p->flags & IOMMU_DETECTED) && p->late_init)
206 /* Must execute after PCI subsystem */
207 rootfs_initcall(pci_iommu_init);
210 /* Many VIA bridges seem to corrupt data for DAC. Disable it here */
212 static void via_no_dac(struct pci_dev *dev)
214 if (forbid_dac == 0) {
215 dev_info(&dev->dev, "disabling DAC on VIA PCI bridge\n");
219 DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID,
220 PCI_CLASS_BRIDGE_PCI, 8, via_no_dac);