1 // SPDX-License-Identifier: GPL-2.0
2 
3 /* Glue code to lib/swiotlb-xen.c */
4 
5 #include <linux/dma-map-ops.h>
6 #include <linux/pci.h>
7 #include <xen/swiotlb-xen.h>
8 
9 #include <asm/xen/hypervisor.h>
10 #include <xen/xen.h>
11 #include <asm/iommu_table.h>
12 
13 
14 #include <asm/xen/swiotlb-xen.h>
15 #ifdef CONFIG_X86_64
16 #include <asm/iommu.h>
17 #include <asm/dma.h>
18 #endif
19 #include <linux/export.h>
20 
21 static int xen_swiotlb __read_mostly;
22 
23 /*
24  * pci_xen_swiotlb_detect - set xen_swiotlb to 1 if necessary
25  *
26  * This returns non-zero if we are forced to use xen_swiotlb (by the boot
27  * option).
28  */
pci_xen_swiotlb_detect(void)29 int __init pci_xen_swiotlb_detect(void)
30 {
31 
32 	if (!xen_pv_domain())
33 		return 0;
34 
35 	/* If running as PV guest, either iommu=soft, or swiotlb=force will
36 	 * activate this IOMMU. If running as PV privileged, activate it
37 	 * irregardless.
38 	 */
39 	if (xen_initial_domain() || swiotlb || swiotlb_force == SWIOTLB_FORCE)
40 		xen_swiotlb = 1;
41 
42 	/* If we are running under Xen, we MUST disable the native SWIOTLB.
43 	 * Don't worry about swiotlb_force flag activating the native, as
44 	 * the 'swiotlb' flag is the only one turning it on. */
45 	swiotlb = 0;
46 
47 #ifdef CONFIG_X86_64
48 	/* pci_swiotlb_detect_4gb turns on native SWIOTLB if no_iommu == 0
49 	 * (so no iommu=X command line over-writes).
50 	 * Considering that PV guests do not want the *native SWIOTLB* but
51 	 * only Xen SWIOTLB it is not useful to us so set no_iommu=1 here.
52 	 */
53 	if (max_pfn > MAX_DMA32_PFN)
54 		no_iommu = 1;
55 #endif
56 	return xen_swiotlb;
57 }
58 
pci_xen_swiotlb_init(void)59 static void __init pci_xen_swiotlb_init(void)
60 {
61 	if (xen_swiotlb) {
62 		xen_swiotlb_init_early();
63 		dma_ops = &xen_swiotlb_dma_ops;
64 
65 #ifdef CONFIG_PCI
66 		/* Make sure ACS will be enabled */
67 		pci_request_acs();
68 #endif
69 	}
70 }
71 
pci_xen_swiotlb_init_late(void)72 int pci_xen_swiotlb_init_late(void)
73 {
74 	int rc;
75 
76 	if (xen_swiotlb)
77 		return 0;
78 
79 	rc = xen_swiotlb_init();
80 	if (rc)
81 		return rc;
82 
83 	dma_ops = &xen_swiotlb_dma_ops;
84 #ifdef CONFIG_PCI
85 	/* Make sure ACS will be enabled */
86 	pci_request_acs();
87 #endif
88 
89 	return 0;
90 }
91 EXPORT_SYMBOL_GPL(pci_xen_swiotlb_init_late);
92 
93 IOMMU_INIT_FINISH(pci_xen_swiotlb_detect,
94 		  NULL,
95 		  pci_xen_swiotlb_init,
96 		  NULL);
97