@samitouri / QOSamiQemu
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1 /*
2 * Virtual Machine Clock Device
3 *
4 * Copyright © 2024 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 #include "qapi/error.h"
14 #include "qemu/module.h"
15 #include "hw/i386/e820_memory_layout.h"
16 #include "hw/acpi/acpi.h"
17 #include "hw/acpi/aml-build.h"
18 #include "hw/acpi/vmclock.h"
19 #include "hw/nvram/fw_cfg.h"
20 #include "hw/core/qdev-properties.h"
21 #include "hw/core/qdev-properties-system.h"
22 #include "migration/vmstate.h"
23 #include "system/reset.h"
24
25 #include "standard-headers/linux/vmclock-abi.h"
26
27 void vmclock_build_acpi(VmclockState *vms, GArray *table_data,
28 BIOSLinker *linker, const char *oem_id)
29 {
30 Aml *ssdt, *dev, *scope, *crs;
31 AcpiTable table = { .sig = "SSDT", .rev = 1,
32 .oem_id = oem_id, .oem_table_id = "VMCLOCK" };
33
34 /* Put VMCLOCK into a separate SSDT table */
35 acpi_table_begin(&table, table_data);
36 ssdt = init_aml_allocator();
37
38 scope = aml_scope("\\_SB");
39 dev = aml_device("VCLK");
40 aml_append(dev, aml_name_decl("_HID", aml_string("AMZNC10C")));
41 aml_append(dev, aml_name_decl("_CID", aml_string("VMCLOCK")));
42 aml_append(dev, aml_name_decl("_DDN", aml_string("VMCLOCK")));
43
44 /* Simple status method */
45 aml_append(dev, aml_name_decl("_STA", aml_int(0xf)));
46
47 crs = aml_resource_template();
48 aml_append(crs, aml_qword_memory(AML_POS_DECODE,
49 AML_MIN_FIXED, AML_MAX_FIXED,
50 AML_CACHEABLE, AML_READ_ONLY,
51 0xffffffffffffffffULL,
52 vms->physaddr,
53 vms->physaddr + VMCLOCK_SIZE - 1,
54 0, VMCLOCK_SIZE));
55 aml_append(dev, aml_name_decl("_CRS", crs));
56 aml_append(scope, dev);
57 aml_append(ssdt, scope);
58
59 g_array_append_vals(table_data, ssdt->buf->data, ssdt->buf->len);
60 acpi_table_end(linker, &table);
61 free_aml_allocator();
62 }
63
64 static void vmclock_update_guest(VmclockState *vms)
65 {
66 uint64_t disruption_marker;
67 uint32_t seq_count;
68
69 if (!vms->clk) {
70 return;
71 }
72
73 seq_count = le32_to_cpu(vms->clk->seq_count) | 1;
74 vms->clk->seq_count = cpu_to_le32(seq_count);
75 /* These barriers pair with read barriers in the guest */
76 smp_wmb();
77
78 disruption_marker = le64_to_cpu(vms->clk->disruption_marker);
79 disruption_marker++;
80 vms->clk->disruption_marker = cpu_to_le64(disruption_marker);
81
82 /* These barriers pair with read barriers in the guest */
83 smp_wmb();
84 vms->clk->seq_count = cpu_to_le32(seq_count + 1);
85 }
86
87 /*
88 * After restoring an image, we need to update the guest memory to notify
89 * it of clock disruption.
90 */
91 static int vmclock_post_load(void *opaque, int version_id)
92 {
93 VmclockState *vms = opaque;
94
95 vmclock_update_guest(vms);
96 return 0;
97 }
98
99 static const VMStateDescription vmstate_vmclock = {
100 .name = "vmclock",
101 .version_id = 1,
102 .minimum_version_id = 1,
103 .post_load = vmclock_post_load,
104 .fields = (const VMStateField[]) {
105 VMSTATE_UINT64(physaddr, VmclockState),
106 VMSTATE_END_OF_LIST()
107 },
108 };
109
110 static void vmclock_handle_reset(void *opaque)
111 {
112 VmclockState *vms = VMCLOCK(opaque);
113
114 if (!memory_region_is_mapped(&vms->clk_page)) {
115 memory_region_add_subregion_overlap(get_system_memory(),
116 vms->physaddr,
117 &vms->clk_page, 0);
118 }
119 }
120
121 static void vmclock_realize(DeviceState *dev, Error **errp)
122 {
123 VmclockState *vms = VMCLOCK(dev);
124
125 /*
126 * Given that this function is executing, there is at least one VMCLOCK
127 * device. Check if there are several.
128 */
129 if (!find_vmclock_dev()) {
130 error_setg(errp, "at most one %s device is permitted", TYPE_VMCLOCK);
131 return;
132 }
133
134 vms->physaddr = VMCLOCK_ADDR;
135
136 e820_add_entry(vms->physaddr, VMCLOCK_SIZE, E820_RESERVED);
137
138 memory_region_init_ram(&vms->clk_page, OBJECT(dev), "vmclock_page",
139 VMCLOCK_SIZE, &error_abort);
140 memory_region_set_enabled(&vms->clk_page, true);
141 vms->clk = memory_region_get_ram_ptr(&vms->clk_page);
142 memset(vms->clk, 0, VMCLOCK_SIZE);
143
144 vms->clk->magic = cpu_to_le32(VMCLOCK_MAGIC);
145 vms->clk->size = cpu_to_le16(VMCLOCK_SIZE);
146 vms->clk->version = cpu_to_le16(1);
147
148 /* These are all zero and thus default, but be explicit */
149 vms->clk->clock_status = VMCLOCK_STATUS_UNKNOWN;
150 vms->clk->counter_id = VMCLOCK_COUNTER_INVALID;
151
152 qemu_register_reset(vmclock_handle_reset, vms);
153
154 vmclock_update_guest(vms);
155 }
156
157 static void vmclock_device_class_init(ObjectClass *klass, const void *data)
158 {
159 DeviceClass *dc = DEVICE_CLASS(klass);
160
161 dc->vmsd = &vmstate_vmclock;
162 dc->realize = vmclock_realize;
163 dc->hotpluggable = false;
164 set_bit(DEVICE_CATEGORY_MISC, dc->categories);
165 }
166
167 static const TypeInfo vmclock_device_info = {
168 .name = TYPE_VMCLOCK,
169 .parent = TYPE_DEVICE,
170 .instance_size = sizeof(VmclockState),
171 .class_init = vmclock_device_class_init,
172 };
173
174 static void vmclock_register_types(void)
175 {
176 type_register_static(&vmclock_device_info);
177 }
178
179 type_init(vmclock_register_types)