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virtio_mem.h
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/* SPDX-License-Identifier: BSD-3-Clause */ /* * Virtio Mem Device * * Copyright Red Hat, Inc. 2020 * * Authors: * David Hildenbrand <david@redhat.com> * * This header is BSD licensed so anyone can use the definitions * to implement compatible drivers/servers: * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of IBM nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL IBM OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #ifndef _LINUX_VIRTIO_MEM_H #define _LINUX_VIRTIO_MEM_H #include <linux/types.h> #include <linux/virtio_types.h> #include <linux/virtio_ids.h> #include <linux/virtio_config.h> /* * Each virtio-mem device manages a dedicated region in physical address * space. Each device can belong to a single NUMA node, multiple devices * for a single NUMA node are possible. A virtio-mem device is like a * "resizable DIMM" consisting of small memory blocks that can be plugged * or unplugged. The device driver is responsible for (un)plugging memory * blocks on demand. * * Virtio-mem devices can only operate on their assigned memory region in * order to (un)plug memory. A device cannot (un)plug memory belonging to * other devices. * * The "region_size" corresponds to the maximum amount of memory that can * be provided by a device. The "size" corresponds to the amount of memory * that is currently plugged. "requested_size" corresponds to a request * from the device to the device driver to (un)plug blocks. The * device driver should try to (un)plug blocks in order to reach the * "requested_size". It is impossible to plug more memory than requested. * * The "usable_region_size" represents the memory region that can actually * be used to (un)plug memory. It is always at least as big as the * "requested_size" and will grow dynamically. It will only shrink when * explicitly triggered (VIRTIO_MEM_REQ_UNPLUG). * * There are no guarantees what will happen if unplugged memory is * read/written. In general, unplugged memory should not be touched, because * the resulting action is undefined. There is one exception: without * VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE, unplugged memory inside the usable * region can be read, to simplify creation of memory dumps. * * It can happen that the device cannot process a request, because it is * busy. The device driver has to retry later. * * Usually, during system resets all memory will get unplugged, so the * device driver can start with a clean state. However, in specific * scenarios (if the device is busy) it can happen that the device still * has memory plugged. The device driver can request to unplug all memory * (VIRTIO_MEM_REQ_UNPLUG) - which might take a while to succeed if the * device is busy. */ /* --- virtio-mem: feature bits --- */ /* node_id is an ACPI PXM and is valid */ #define VIRTIO_MEM_F_ACPI_PXM 0 /* unplugged memory must not be accessed */ #define VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE 1 /* --- virtio-mem: guest -> host requests --- */ /* request to plug memory blocks */ #define VIRTIO_MEM_REQ_PLUG 0 /* request to unplug memory blocks */ #define VIRTIO_MEM_REQ_UNPLUG 1 /* request to unplug all blocks and shrink the usable size */ #define VIRTIO_MEM_REQ_UNPLUG_ALL 2 /* request information about the plugged state of memory blocks */ #define VIRTIO_MEM_REQ_STATE 3 struct virtio_mem_req_plug { __virtio64 addr; __virtio16 nb_blocks; __virtio16 padding[3]; }; struct virtio_mem_req_unplug { __virtio64 addr; __virtio16 nb_blocks; __virtio16 padding[3]; }; struct virtio_mem_req_state { __virtio64 addr; __virtio16 nb_blocks; __virtio16 padding[3]; }; struct virtio_mem_req { __virtio16 type; __virtio16 padding[3]; union { struct virtio_mem_req_plug plug; struct virtio_mem_req_unplug unplug; struct virtio_mem_req_state state; } u; }; /* --- virtio-mem: host -> guest response --- */ /* * Request processed successfully, applicable for * - VIRTIO_MEM_REQ_PLUG * - VIRTIO_MEM_REQ_UNPLUG * - VIRTIO_MEM_REQ_UNPLUG_ALL * - VIRTIO_MEM_REQ_STATE */ #define VIRTIO_MEM_RESP_ACK 0 /* * Request denied - e.g. trying to plug more than requested, applicable for * - VIRTIO_MEM_REQ_PLUG */ #define VIRTIO_MEM_RESP_NACK 1 /* * Request cannot be processed right now, try again later, applicable for * - VIRTIO_MEM_REQ_PLUG * - VIRTIO_MEM_REQ_UNPLUG * - VIRTIO_MEM_REQ_UNPLUG_ALL */ #define VIRTIO_MEM_RESP_BUSY 2 /* * Error in request (e.g. addresses/alignment), applicable for * - VIRTIO_MEM_REQ_PLUG * - VIRTIO_MEM_REQ_UNPLUG * - VIRTIO_MEM_REQ_STATE */ #define VIRTIO_MEM_RESP_ERROR 3 /* State of memory blocks is "plugged" */ #define VIRTIO_MEM_STATE_PLUGGED 0 /* State of memory blocks is "unplugged" */ #define VIRTIO_MEM_STATE_UNPLUGGED 1 /* State of memory blocks is "mixed" */ #define VIRTIO_MEM_STATE_MIXED 2 struct virtio_mem_resp_state { __virtio16 state; }; struct virtio_mem_resp { __virtio16 type; __virtio16 padding[3]; union { struct virtio_mem_resp_state state; } u; }; /* --- virtio-mem: configuration --- */ struct virtio_mem_config { /* Block size and alignment. Cannot change. */ __le64 block_size; /* Valid with VIRTIO_MEM_F_ACPI_PXM. Cannot change. */ __le16 node_id; __u8 padding[6]; /* Start address of the memory region. Cannot change. */ __le64 addr; /* Region size (maximum). Cannot change. */ __le64 region_size; /* * Currently usable region size. Can grow up to region_size. Can * shrink due to VIRTIO_MEM_REQ_UNPLUG_ALL (in which case no config * update will be sent). */ __le64 usable_region_size; /* * Currently used size. Changes due to plug/unplug requests, but no * config updates will be sent. */ __le64 plugged_size; /* Requested size. New plug requests cannot exceed it. Can change. */ __le64 requested_size; }; #endif /* _LINUX_VIRTIO_MEM_H */