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 */
25static int xen_platform_pci_unplug;
26static int xen_emul_unplug;
27
28static 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
61bool 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}
90EXPORT_SYMBOL_GPL(xen_has_pv_devices);
91
92static 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
101bool xen_has_pv_nic_devices(void)
102{
103	return __xen_has_pv_device(XEN_UNPLUG_ALL_NICS | XEN_UNPLUG_ALL);
104}
105EXPORT_SYMBOL_GPL(xen_has_pv_nic_devices);
106
107bool 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}
112EXPORT_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 */
119bool 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}
133EXPORT_SYMBOL_GPL(xen_has_pv_and_legacy_disk_devices);
134
135void 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
179static 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}
210early_param("xen_emul_unplug", parse_xen_emul_unplug);
211