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