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
18int 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 */
26int __init pci_swiotlb_detect_override(void)
27{
28	if (swiotlb_force == SWIOTLB_FORCE)
29		swiotlb = 1;
30
31	return swiotlb;
32}
33IOMMU_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 */
42int __init pci_swiotlb_detect_4gb(void)
43{
44	/* don't initialize swiotlb if iommu=off (no_iommu=1) */
45#ifdef CONFIG_X86_64
46	if (!no_iommu && max_possible_pfn > MAX_DMA32_PFN)
47		swiotlb = 1;
48#endif
49
50	/*
51	 * If SME is active then swiotlb will be set to 1 so that bounce
52	 * buffers are allocated and used for devices that do not support
53	 * the addressing range required for the encryption mask.
54	 */
55	if (sme_active())
56		swiotlb = 1;
57
58	return swiotlb;
59}
60IOMMU_INIT(pci_swiotlb_detect_4gb,
61	   pci_swiotlb_detect_override,
62	   pci_swiotlb_init,
63	   pci_swiotlb_late_init);
64
65void __init pci_swiotlb_init(void)
66{
67	if (swiotlb) {
68		swiotlb_init(0);
69		dma_ops = &swiotlb_dma_ops;
70	}
71}
72
73void __init pci_swiotlb_late_init(void)
74{
75	/* An IOMMU turned us off. */
76	if (!swiotlb)
77		swiotlb_exit();
78	else {
79		printk(KERN_INFO "PCI-DMA: "
80		       "Using software bounce buffering for IO (SWIOTLB)\n");
81		swiotlb_print_info();
82	}
83}