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/bootmem.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  */
pci_swiotlb_detect_override(void)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  */
pci_swiotlb_detect_4gb(void)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 
pci_swiotlb_init(void)63 void __init pci_swiotlb_init(void)
64 {
65 	if (swiotlb) {
66 		swiotlb_init(0);
67 		dma_ops = &swiotlb_dma_ops;
68 	}
69 }
70 
pci_swiotlb_late_init(void)71 void __init pci_swiotlb_late_init(void)
72 {
73 	/* An IOMMU turned us off. */
74 	if (!swiotlb)
75 		swiotlb_exit();
76 	else {
77 		printk(KERN_INFO "PCI-DMA: "
78 		       "Using software bounce buffering for IO (SWIOTLB)\n");
79 		swiotlb_print_info();
80 	}
81 }
82