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
17int 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 */
25int __init pci_swiotlb_detect_override(void)
26{
27	if (swiotlb_force == SWIOTLB_FORCE)
28		swiotlb = 1;
29
30	return swiotlb;
31}
32IOMMU_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 */
41int __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}
57IOMMU_INIT(pci_swiotlb_detect_4gb,
58	   pci_swiotlb_detect_override,
59	   pci_swiotlb_init,
60	   pci_swiotlb_late_init);
61
62void __init pci_swiotlb_init(void)
63{
64	if (swiotlb)
65		swiotlb_init(0);
66}
67
68void __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}