1 // SPDX-License-Identifier: GPL-2.0
2 
3 /******************************************************************************
4  * platform-pci-unplug.c
5  *
6  * Xen platform PCI device driver
7  * Copyright (c) 2010, Citrix
8  */
9 
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 
12 #include <linux/init.h>
13 #include <linux/io.h>
14 #include <linux/export.h>
15 
16 #include <xen/xen.h>
17 #include <xen/platform_pci.h>
18 #include "xen-ops.h"
19 
20 #define XEN_PLATFORM_ERR_MAGIC -1
21 #define XEN_PLATFORM_ERR_PROTOCOL -2
22 #define XEN_PLATFORM_ERR_BLACKLIST -3
23 
24 /* store the value of xen_emul_unplug after the unplug is done */
25 static int xen_platform_pci_unplug;
26 static int xen_emul_unplug;
27 
28 static int check_platform_magic(void)
29 {
30 	short magic;
31 	char protocol;
32 
33 	magic = inw(XEN_IOPORT_MAGIC);
34 	if (magic != XEN_IOPORT_MAGIC_VAL) {
35 		pr_err("Xen Platform PCI: unrecognised magic value\n");
36 		return XEN_PLATFORM_ERR_MAGIC;
37 	}
38 
39 	protocol = inb(XEN_IOPORT_PROTOVER);
40 
41 	pr_debug("Xen Platform PCI: I/O protocol version %d\n",
42 			protocol);
43 
44 	switch (protocol) {
45 	case 1:
46 		outw(XEN_IOPORT_LINUX_PRODNUM, XEN_IOPORT_PRODNUM);
47 		outl(XEN_IOPORT_LINUX_DRVVER, XEN_IOPORT_DRVVER);
48 		if (inw(XEN_IOPORT_MAGIC) != XEN_IOPORT_MAGIC_VAL) {
49 			pr_err("Xen Platform: blacklisted by host\n");
50 			return XEN_PLATFORM_ERR_BLACKLIST;
51 		}
52 		break;
53 	default:
54 		pr_warn("Xen Platform PCI: unknown I/O protocol version\n");
55 		return XEN_PLATFORM_ERR_PROTOCOL;
56 	}
57 
58 	return 0;
59 }
60 
61 bool xen_has_pv_devices(void)
62 {
63 	if (!xen_domain())
64 		return false;
65 
66 	/* PV and PVH domains always have them. */
67 	if (xen_pv_domain() || xen_pvh_domain())
68 		return true;
69 
70 	/* And user has xen_platform_pci=0 set in guest config as
71 	 * driver did not modify the value. */
72 	if (xen_platform_pci_unplug == 0)
73 		return false;
74 
75 	if (xen_platform_pci_unplug & XEN_UNPLUG_NEVER)
76 		return false;
77 
78 	if (xen_platform_pci_unplug & XEN_UNPLUG_ALL)
79 		return true;
80 
81 	/* This is an odd one - we are going to run legacy
82 	 * and PV drivers at the same time. */
83 	if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY)
84 		return true;
85 
86 	/* And the caller has to follow with xen_pv_{disk,nic}_devices
87 	 * to be certain which driver can load. */
88 	return false;
89 }
90 EXPORT_SYMBOL_GPL(xen_has_pv_devices);
91 
92 static bool __xen_has_pv_device(int state)
93 {
94 	/* HVM domains might or might not */
95 	if (xen_hvm_domain() && (xen_platform_pci_unplug & state))
96 		return true;
97 
98 	return xen_has_pv_devices();
99 }
100 
101 bool xen_has_pv_nic_devices(void)
102 {
103 	return __xen_has_pv_device(XEN_UNPLUG_ALL_NICS | XEN_UNPLUG_ALL);
104 }
105 EXPORT_SYMBOL_GPL(xen_has_pv_nic_devices);
106 
107 bool xen_has_pv_disk_devices(void)
108 {
109 	return __xen_has_pv_device(XEN_UNPLUG_ALL_IDE_DISKS |
110 				   XEN_UNPLUG_AUX_IDE_DISKS | XEN_UNPLUG_ALL);
111 }
112 EXPORT_SYMBOL_GPL(xen_has_pv_disk_devices);
113 
114 /*
115  * This one is odd - it determines whether you want to run PV _and_
116  * legacy (IDE) drivers together. This combination is only possible
117  * under HVM.
118  */
119 bool xen_has_pv_and_legacy_disk_devices(void)
120 {
121 	if (!xen_domain())
122 		return false;
123 
124 	/* N.B. This is only ever used in HVM mode */
125 	if (xen_pv_domain())
126 		return false;
127 
128 	if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY)
129 		return true;
130 
131 	return false;
132 }
133 EXPORT_SYMBOL_GPL(xen_has_pv_and_legacy_disk_devices);
134 
135 void xen_unplug_emulated_devices(void)
136 {
137 	int r;
138 
139 	/* PVH guests don't have emulated devices. */
140 	if (xen_pvh_domain())
141 		return;
142 
143 	/* user explicitly requested no unplug */
144 	if (xen_emul_unplug & XEN_UNPLUG_NEVER)
145 		return;
146 	/* check the version of the xen platform PCI device */
147 	r = check_platform_magic();
148 	/* If the version matches enable the Xen platform PCI driver.
149 	 * Also enable the Xen platform PCI driver if the host does
150 	 * not support the unplug protocol (XEN_PLATFORM_ERR_MAGIC)
151 	 * but the user told us that unplugging is unnecessary. */
152 	if (r && !(r == XEN_PLATFORM_ERR_MAGIC &&
153 			(xen_emul_unplug & XEN_UNPLUG_UNNECESSARY)))
154 		return;
155 	/* Set the default value of xen_emul_unplug depending on whether or
156 	 * not the Xen PV frontends and the Xen platform PCI driver have
157 	 * been compiled for this kernel (modules or built-in are both OK). */
158 	if (!xen_emul_unplug) {
159 		if (xen_must_unplug_nics()) {
160 			pr_info("Netfront and the Xen platform PCI driver have "
161 					"been compiled for this kernel: unplug emulated NICs.\n");
162 			xen_emul_unplug |= XEN_UNPLUG_ALL_NICS;
163 		}
164 		if (xen_must_unplug_disks()) {
165 			pr_info("Blkfront and the Xen platform PCI driver have "
166 					"been compiled for this kernel: unplug emulated disks.\n"
167 					"You might have to change the root device\n"
168 					"from /dev/hd[a-d] to /dev/xvd[a-d]\n"
169 					"in your root= kernel command line option\n");
170 			xen_emul_unplug |= XEN_UNPLUG_ALL_IDE_DISKS;
171 		}
172 	}
173 	/* Now unplug the emulated devices */
174 	if (!(xen_emul_unplug & XEN_UNPLUG_UNNECESSARY))
175 		outw(xen_emul_unplug, XEN_IOPORT_UNPLUG);
176 	xen_platform_pci_unplug = xen_emul_unplug;
177 }
178 
179 static int __init parse_xen_emul_unplug(char *arg)
180 {
181 	char *p, *q;
182 	int l;
183 
184 	for (p = arg; p; p = q) {
185 		q = strchr(p, ',');
186 		if (q) {
187 			l = q - p;
188 			q++;
189 		} else {
190 			l = strlen(p);
191 		}
192 		if (!strncmp(p, "all", l))
193 			xen_emul_unplug |= XEN_UNPLUG_ALL;
194 		else if (!strncmp(p, "ide-disks", l))
195 			xen_emul_unplug |= XEN_UNPLUG_ALL_IDE_DISKS;
196 		else if (!strncmp(p, "aux-ide-disks", l))
197 			xen_emul_unplug |= XEN_UNPLUG_AUX_IDE_DISKS;
198 		else if (!strncmp(p, "nics", l))
199 			xen_emul_unplug |= XEN_UNPLUG_ALL_NICS;
200 		else if (!strncmp(p, "unnecessary", l))
201 			xen_emul_unplug |= XEN_UNPLUG_UNNECESSARY;
202 		else if (!strncmp(p, "never", l))
203 			xen_emul_unplug |= XEN_UNPLUG_NEVER;
204 		else
205 			pr_warn("unrecognised option '%s' "
206 				 "in parameter 'xen_emul_unplug'\n", p);
207 	}
208 	return 0;
209 }
210 early_param("xen_emul_unplug", parse_xen_emul_unplug);
211