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1 /*
2 * QEMU Xen emulation: Primary console support
3 *
4 * Copyright © 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved.
5 *
6 * Authors: David Woodhouse <dwmw2@infradead.org>
7 *
8 * This work is licensed under the terms of the GNU GPL, version 2 or later.
9 * See the COPYING file in the top-level directory.
10 */
11
12 #include "qemu/osdep.h"
13
14 #include "qapi/error.h"
15
16 #include "hw/core/sysbus.h"
17 #include "hw/xen/xen.h"
18 #include "hw/xen/xen_backend_ops.h"
19 #include "xen_evtchn.h"
20 #include "xen_overlay.h"
21 #include "xen_primary_console.h"
22
23 #include "system/kvm.h"
24 #include "system/kvm_xen.h"
25
26 #include "trace.h"
27
28 #include "hw/xen/interface/event_channel.h"
29 #include "hw/xen/interface/grant_table.h"
30
31 #define TYPE_XEN_PRIMARY_CONSOLE "xen-primary-console"
32 OBJECT_DECLARE_SIMPLE_TYPE(XenPrimaryConsoleState, XEN_PRIMARY_CONSOLE)
33
34 struct XenPrimaryConsoleState {
35 /*< private >*/
36 SysBusDevice busdev;
37 /*< public >*/
38
39 MemoryRegion console_page;
40 void *cp;
41
42 evtchn_port_t guest_port;
43 evtchn_port_t be_port;
44
45 struct xengntdev_handle *gt;
46 void *granted_xs;
47 };
48
49 struct XenPrimaryConsoleState *xen_primary_console_singleton;
50
51 static void xen_primary_console_realize(DeviceState *dev, Error **errp)
52 {
53 XenPrimaryConsoleState *s = XEN_PRIMARY_CONSOLE(dev);
54
55 if (xen_mode != XEN_EMULATE) {
56 error_setg(errp, "Xen primary console support is for Xen emulation");
57 return;
58 }
59
60 memory_region_init_ram(&s->console_page, OBJECT(dev), "xen:console_page",
61 XEN_PAGE_SIZE, &error_abort);
62 memory_region_set_enabled(&s->console_page, true);
63 s->cp = memory_region_get_ram_ptr(&s->console_page);
64 memset(s->cp, 0, XEN_PAGE_SIZE);
65
66 /* We can't map it this early as KVM isn't ready */
67 xen_primary_console_singleton = s;
68 }
69
70 static void xen_primary_console_class_init(ObjectClass *klass, const void *data)
71 {
72 DeviceClass *dc = DEVICE_CLASS(klass);
73
74 dc->realize = xen_primary_console_realize;
75 }
76
77 static const TypeInfo xen_primary_console_info = {
78 .name = TYPE_XEN_PRIMARY_CONSOLE,
79 .parent = TYPE_SYS_BUS_DEVICE,
80 .instance_size = sizeof(XenPrimaryConsoleState),
81 .class_init = xen_primary_console_class_init,
82 };
83
84
85 void xen_primary_console_create(void)
86 {
87 DeviceState *dev = sysbus_create_simple(TYPE_XEN_PRIMARY_CONSOLE, -1, NULL);
88
89 trace_xen_primary_console_create();
90
91 xen_primary_console_singleton = XEN_PRIMARY_CONSOLE(dev);
92
93 /*
94 * Defer the init (xen_primary_console_reset()) until KVM is set up and the
95 * overlay page can be mapped.
96 */
97 }
98
99 static void xen_primary_console_register_types(void)
100 {
101 type_register_static(&xen_primary_console_info);
102 }
103
104 type_init(xen_primary_console_register_types)
105
106 uint16_t xen_primary_console_get_port(void)
107 {
108 XenPrimaryConsoleState *s = xen_primary_console_singleton;
109 if (!s) {
110 return 0;
111 }
112 return s->guest_port;
113 }
114
115 void xen_primary_console_set_be_port(uint16_t port)
116 {
117 XenPrimaryConsoleState *s = xen_primary_console_singleton;
118 if (s) {
119 s->be_port = port;
120 }
121 }
122
123 uint64_t xen_primary_console_get_pfn(void)
124 {
125 XenPrimaryConsoleState *s = xen_primary_console_singleton;
126 if (!s) {
127 return 0;
128 }
129 return XEN_SPECIAL_PFN(CONSOLE);
130 }
131
132 void *xen_primary_console_get_map(void)
133 {
134 XenPrimaryConsoleState *s = xen_primary_console_singleton;
135 if (!s) {
136 return 0;
137 }
138 return s->cp;
139 }
140
141 static void alloc_guest_port(XenPrimaryConsoleState *s)
142 {
143 struct evtchn_alloc_unbound alloc = {
144 .dom = DOMID_SELF,
145 .remote_dom = DOMID_QEMU,
146 };
147
148 if (!xen_evtchn_alloc_unbound_op(&alloc)) {
149 s->guest_port = alloc.port;
150 }
151 }
152
153 static void rebind_guest_port(XenPrimaryConsoleState *s)
154 {
155 struct evtchn_bind_interdomain inter = {
156 .remote_dom = DOMID_QEMU,
157 .remote_port = s->be_port,
158 };
159
160 if (!xen_evtchn_bind_interdomain_op(&inter)) {
161 s->guest_port = inter.local_port;
162 }
163
164 s->be_port = 0;
165 }
166
167 int xen_primary_console_reset(void)
168 {
169 XenPrimaryConsoleState *s = xen_primary_console_singleton;
170 if (!s) {
171 return 0;
172 }
173
174 if (!memory_region_is_mapped(&s->console_page)) {
175 uint64_t gpa = XEN_SPECIAL_PFN(CONSOLE) << TARGET_PAGE_BITS;
176 xen_overlay_do_map_page(&s->console_page, gpa);
177 }
178
179 if (s->be_port) {
180 rebind_guest_port(s);
181 } else {
182 alloc_guest_port(s);
183 }
184
185 trace_xen_primary_console_reset(s->guest_port);
186
187 s->gt = qemu_xen_gnttab_open();
188 uint32_t xs_gntref = GNTTAB_RESERVED_CONSOLE;
189 s->granted_xs = qemu_xen_gnttab_map_refs(s->gt, 1, xen_domid, &xs_gntref,
190 PROT_READ | PROT_WRITE);
191
192 return 0;
193 }