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1 | /* SPDX-License-Identifier: BSD-3-Clause */ |
2 | /* | |
3 | * Virtio Mem Device | |
4 | * | |
5 | * Copyright Red Hat, Inc. 2020 | |
6 | * | |
7 | * Authors: | |
8 | * David Hildenbrand <david@redhat.com> | |
9 | * | |
10 | * This header is BSD licensed so anyone can use the definitions | |
11 | * to implement compatible drivers/servers: | |
12 | * | |
13 | * Redistribution and use in source and binary forms, with or without | |
14 | * modification, are permitted provided that the following conditions | |
15 | * are met: | |
16 | * 1. Redistributions of source code must retain the above copyright | |
17 | * notice, this list of conditions and the following disclaimer. | |
18 | * 2. Redistributions in binary form must reproduce the above copyright | |
19 | * notice, this list of conditions and the following disclaimer in the | |
20 | * documentation and/or other materials provided with the distribution. | |
21 | * 3. Neither the name of IBM nor the names of its contributors | |
22 | * may be used to endorse or promote products derived from this software | |
23 | * without specific prior written permission. | |
24 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
25 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
26 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS | |
27 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL IBM OR | |
28 | * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
29 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | |
30 | * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF | |
31 | * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND | |
32 | * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, | |
33 | * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT | |
34 | * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
35 | * SUCH DAMAGE. | |
36 | */ | |
37 | ||
38 | #ifndef _LINUX_VIRTIO_MEM_H | |
39 | #define _LINUX_VIRTIO_MEM_H | |
40 | ||
41 | #include <linux/types.h> | |
42 | #include <linux/virtio_types.h> | |
43 | #include <linux/virtio_ids.h> | |
44 | #include <linux/virtio_config.h> | |
45 | ||
46 | /* | |
47 | * Each virtio-mem device manages a dedicated region in physical address | |
48 | * space. Each device can belong to a single NUMA node, multiple devices | |
49 | * for a single NUMA node are possible. A virtio-mem device is like a | |
50 | * "resizable DIMM" consisting of small memory blocks that can be plugged | |
51 | * or unplugged. The device driver is responsible for (un)plugging memory | |
52 | * blocks on demand. | |
53 | * | |
54 | * Virtio-mem devices can only operate on their assigned memory region in | |
55 | * order to (un)plug memory. A device cannot (un)plug memory belonging to | |
56 | * other devices. | |
57 | * | |
58 | * The "region_size" corresponds to the maximum amount of memory that can | |
59 | * be provided by a device. The "size" corresponds to the amount of memory | |
60 | * that is currently plugged. "requested_size" corresponds to a request | |
61 | * from the device to the device driver to (un)plug blocks. The | |
62 | * device driver should try to (un)plug blocks in order to reach the | |
63 | * "requested_size". It is impossible to plug more memory than requested. | |
64 | * | |
65 | * The "usable_region_size" represents the memory region that can actually | |
66 | * be used to (un)plug memory. It is always at least as big as the | |
67 | * "requested_size" and will grow dynamically. It will only shrink when | |
68 | * explicitly triggered (VIRTIO_MEM_REQ_UNPLUG). | |
69 | * | |
70 | * There are no guarantees what will happen if unplugged memory is | |
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71 | * read/written. In general, unplugged memory should not be touched, because |
72 | * the resulting action is undefined. There is one exception: without | |
73 | * VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE, unplugged memory inside the usable | |
74 | * region can be read, to simplify creation of memory dumps. | |
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75 | * |
76 | * It can happen that the device cannot process a request, because it is | |
77 | * busy. The device driver has to retry later. | |
78 | * | |
79 | * Usually, during system resets all memory will get unplugged, so the | |
80 | * device driver can start with a clean state. However, in specific | |
81 | * scenarios (if the device is busy) it can happen that the device still | |
82 | * has memory plugged. The device driver can request to unplug all memory | |
83 | * (VIRTIO_MEM_REQ_UNPLUG) - which might take a while to succeed if the | |
84 | * device is busy. | |
85 | */ | |
86 | ||
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87 | /* --- virtio-mem: feature bits --- */ |
88 | ||
89 | /* node_id is an ACPI PXM and is valid */ | |
90 | #define VIRTIO_MEM_F_ACPI_PXM 0 | |
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91 | /* unplugged memory must not be accessed */ |
92 | #define VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE 1 | |
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93 | /* plugged memory will remain plugged when suspending+resuming */ |
94 | #define VIRTIO_MEM_F_PERSISTENT_SUSPEND 2 | |
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95 | |
96 | ||
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97 | /* --- virtio-mem: guest -> host requests --- */ |
98 | ||
99 | /* request to plug memory blocks */ | |
100 | #define VIRTIO_MEM_REQ_PLUG 0 | |
101 | /* request to unplug memory blocks */ | |
102 | #define VIRTIO_MEM_REQ_UNPLUG 1 | |
103 | /* request to unplug all blocks and shrink the usable size */ | |
104 | #define VIRTIO_MEM_REQ_UNPLUG_ALL 2 | |
105 | /* request information about the plugged state of memory blocks */ | |
106 | #define VIRTIO_MEM_REQ_STATE 3 | |
107 | ||
108 | struct virtio_mem_req_plug { | |
109 | __virtio64 addr; | |
110 | __virtio16 nb_blocks; | |
fce8afd7 | 111 | __virtio16 padding[3]; |
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112 | }; |
113 | ||
114 | struct virtio_mem_req_unplug { | |
115 | __virtio64 addr; | |
116 | __virtio16 nb_blocks; | |
fce8afd7 | 117 | __virtio16 padding[3]; |
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118 | }; |
119 | ||
120 | struct virtio_mem_req_state { | |
121 | __virtio64 addr; | |
122 | __virtio16 nb_blocks; | |
fce8afd7 | 123 | __virtio16 padding[3]; |
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124 | }; |
125 | ||
126 | struct virtio_mem_req { | |
127 | __virtio16 type; | |
128 | __virtio16 padding[3]; | |
129 | ||
130 | union { | |
131 | struct virtio_mem_req_plug plug; | |
132 | struct virtio_mem_req_unplug unplug; | |
133 | struct virtio_mem_req_state state; | |
134 | } u; | |
135 | }; | |
136 | ||
137 | ||
138 | /* --- virtio-mem: host -> guest response --- */ | |
139 | ||
140 | /* | |
141 | * Request processed successfully, applicable for | |
142 | * - VIRTIO_MEM_REQ_PLUG | |
143 | * - VIRTIO_MEM_REQ_UNPLUG | |
144 | * - VIRTIO_MEM_REQ_UNPLUG_ALL | |
145 | * - VIRTIO_MEM_REQ_STATE | |
146 | */ | |
147 | #define VIRTIO_MEM_RESP_ACK 0 | |
148 | /* | |
149 | * Request denied - e.g. trying to plug more than requested, applicable for | |
150 | * - VIRTIO_MEM_REQ_PLUG | |
151 | */ | |
152 | #define VIRTIO_MEM_RESP_NACK 1 | |
153 | /* | |
154 | * Request cannot be processed right now, try again later, applicable for | |
155 | * - VIRTIO_MEM_REQ_PLUG | |
156 | * - VIRTIO_MEM_REQ_UNPLUG | |
157 | * - VIRTIO_MEM_REQ_UNPLUG_ALL | |
158 | */ | |
159 | #define VIRTIO_MEM_RESP_BUSY 2 | |
160 | /* | |
161 | * Error in request (e.g. addresses/alignment), applicable for | |
162 | * - VIRTIO_MEM_REQ_PLUG | |
163 | * - VIRTIO_MEM_REQ_UNPLUG | |
164 | * - VIRTIO_MEM_REQ_STATE | |
165 | */ | |
166 | #define VIRTIO_MEM_RESP_ERROR 3 | |
167 | ||
168 | ||
169 | /* State of memory blocks is "plugged" */ | |
170 | #define VIRTIO_MEM_STATE_PLUGGED 0 | |
171 | /* State of memory blocks is "unplugged" */ | |
172 | #define VIRTIO_MEM_STATE_UNPLUGGED 1 | |
173 | /* State of memory blocks is "mixed" */ | |
174 | #define VIRTIO_MEM_STATE_MIXED 2 | |
175 | ||
176 | struct virtio_mem_resp_state { | |
177 | __virtio16 state; | |
178 | }; | |
179 | ||
180 | struct virtio_mem_resp { | |
181 | __virtio16 type; | |
182 | __virtio16 padding[3]; | |
183 | ||
184 | union { | |
185 | struct virtio_mem_resp_state state; | |
186 | } u; | |
187 | }; | |
188 | ||
189 | /* --- virtio-mem: configuration --- */ | |
190 | ||
191 | struct virtio_mem_config { | |
192 | /* Block size and alignment. Cannot change. */ | |
79268954 | 193 | __le64 block_size; |
f2af6d39 | 194 | /* Valid with VIRTIO_MEM_F_ACPI_PXM. Cannot change. */ |
79268954 | 195 | __le16 node_id; |
544fc7db | 196 | __u8 padding[6]; |
5f1f79bb | 197 | /* Start address of the memory region. Cannot change. */ |
79268954 | 198 | __le64 addr; |
5f1f79bb | 199 | /* Region size (maximum). Cannot change. */ |
79268954 | 200 | __le64 region_size; |
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201 | /* |
202 | * Currently usable region size. Can grow up to region_size. Can | |
203 | * shrink due to VIRTIO_MEM_REQ_UNPLUG_ALL (in which case no config | |
204 | * update will be sent). | |
205 | */ | |
79268954 | 206 | __le64 usable_region_size; |
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207 | /* |
208 | * Currently used size. Changes due to plug/unplug requests, but no | |
209 | * config updates will be sent. | |
210 | */ | |
79268954 | 211 | __le64 plugged_size; |
5f1f79bb | 212 | /* Requested size. New plug requests cannot exceed it. Can change. */ |
79268954 | 213 | __le64 requested_size; |
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214 | }; |
215 | ||
216 | #endif /* _LINUX_VIRTIO_MEM_H */ |