1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include <linux/pci.h>
4 #include <linux/cache.h>
5 #include <linux/init.h>
6 #include <linux/swiotlb.h>
7 #include <linux/memblock.h>
8 #include <linux/dma-direct.h>
9 #include <linux/mem_encrypt.h>
10 
11 #include <asm/iommu.h>
12 #include <asm/swiotlb.h>
13 #include <asm/dma.h>
14 #include <asm/xen/swiotlb-xen.h>
15 #include <asm/iommu_table.h>
16 
17 int swiotlb __read_mostly;
18 
19 /*
20  * pci_swiotlb_detect_override - set swiotlb to 1 if necessary
21  *
22  * This returns non-zero if we are forced to use swiotlb (by the boot
23  * option).
24  */
pci_swiotlb_detect_override(void)25 int __init pci_swiotlb_detect_override(void)
26 {
27 	if (swiotlb_force == SWIOTLB_FORCE)
28 		swiotlb = 1;
29 
30 	return swiotlb;
31 }
32 IOMMU_INIT_FINISH(pci_swiotlb_detect_override,
33 		  pci_xen_swiotlb_detect,
34 		  pci_swiotlb_init,
35 		  pci_swiotlb_late_init);
36 
37 /*
38  * If 4GB or more detected (and iommu=off not set) or if SME is active
39  * then set swiotlb to 1 and return 1.
40  */
pci_swiotlb_detect_4gb(void)41 int __init pci_swiotlb_detect_4gb(void)
42 {
43 	/* don't initialize swiotlb if iommu=off (no_iommu=1) */
44 	if (!no_iommu && max_possible_pfn > MAX_DMA32_PFN)
45 		swiotlb = 1;
46 
47 	/*
48 	 * If SME is active then swiotlb will be set to 1 so that bounce
49 	 * buffers are allocated and used for devices that do not support
50 	 * the addressing range required for the encryption mask.
51 	 */
52 	if (sme_active())
53 		swiotlb = 1;
54 
55 	return swiotlb;
56 }
57 IOMMU_INIT(pci_swiotlb_detect_4gb,
58 	   pci_swiotlb_detect_override,
59 	   pci_swiotlb_init,
60 	   pci_swiotlb_late_init);
61 
pci_swiotlb_init(void)62 void __init pci_swiotlb_init(void)
63 {
64 	if (swiotlb)
65 		swiotlb_init(0);
66 }
67 
pci_swiotlb_late_init(void)68 void __init pci_swiotlb_late_init(void)
69 {
70 	/* An IOMMU turned us off. */
71 	if (!swiotlb)
72 		swiotlb_exit();
73 	else {
74 		printk(KERN_INFO "PCI-DMA: "
75 		       "Using software bounce buffering for IO (SWIOTLB)\n");
76 		swiotlb_print_info();
77 	}
78 }
79