qemu/include/hw/virtio/virtio-mem.h

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virtio-mem: Paravirtualized memory hot(un)plug This is the very basic/initial version of virtio-mem. An introduction to virtio-mem can be found in the Linux kernel driver [1]. While it can be used in the current state for hotplug of a smaller amount of memory, it will heavily benefit from resizeable memory regions in the future. Each virtio-mem device manages a memory region (provided via a memory backend). After requested by the hypervisor ("requested-size"), the guest can try to plug/unplug blocks of memory within that region, in order to reach the requested size. Initially, and after a reboot, all memory is unplugged (except in special cases - reboot during postcopy). The guest may only try to plug/unplug blocks of memory within the usable region size. The usable region size is a little bigger than the requested size, to give the device driver some flexibility. The usable region size will only grow, except on reboots or when all memory is requested to get unplugged. The guest can never plug more memory than requested. Unplugged memory will get zapped/discarded, similar to in a balloon device. The block size is variable, however, it is always chosen in a way such that THP splits are avoided (e.g., 2MB). The state of each block (plugged/unplugged) is tracked in a bitmap. As virtio-mem devices (e.g., virtio-mem-pci) will be memory devices, we now expose "VirtioMEMDeviceInfo" via "query-memory-devices". -------------------------------------------------------------------------- There are two important follow-up items that are in the works: 1. Resizeable memory regions: Use resizeable allocations/RAM blocks to grow/shrink along with the usable region size. This avoids creating initially very big VMAs, RAM blocks, and KVM slots. 2. Protection of unplugged memory: Make sure the gust cannot actually make use of unplugged memory. Other follow-up items that are in the works: 1. Exclude unplugged memory during migration (via precopy notifier). 2. Handle remapping of memory. 3. Support for other architectures. -------------------------------------------------------------------------- Example usage (virtio-mem-pci is introduced in follow-up patches): Start QEMU with two virtio-mem devices (one per NUMA node): $ qemu-system-x86_64 -m 4G,maxmem=20G \ -smp sockets=2,cores=2 \ -numa node,nodeid=0,cpus=0-1 -numa node,nodeid=1,cpus=2-3 \ [...] -object memory-backend-ram,id=mem0,size=8G \ -device virtio-mem-pci,id=vm0,memdev=mem0,node=0,requested-size=0M \ -object memory-backend-ram,id=mem1,size=8G \ -device virtio-mem-pci,id=vm1,memdev=mem1,node=1,requested-size=1G Query the configuration: (qemu) info memory-devices Memory device [virtio-mem]: "vm0" memaddr: 0x140000000 node: 0 requested-size: 0 size: 0 max-size: 8589934592 block-size: 2097152 memdev: /objects/mem0 Memory device [virtio-mem]: "vm1" memaddr: 0x340000000 node: 1 requested-size: 1073741824 size: 1073741824 max-size: 8589934592 block-size: 2097152 memdev: /objects/mem1 Add some memory to node 0: (qemu) qom-set vm0 requested-size 500M Remove some memory from node 1: (qemu) qom-set vm1 requested-size 200M Query the configuration again: (qemu) info memory-devices Memory device [virtio-mem]: "vm0" memaddr: 0x140000000 node: 0 requested-size: 524288000 size: 524288000 max-size: 8589934592 block-size: 2097152 memdev: /objects/mem0 Memory device [virtio-mem]: "vm1" memaddr: 0x340000000 node: 1 requested-size: 209715200 size: 209715200 max-size: 8589934592 block-size: 2097152 memdev: /objects/mem1 [1] https://lkml.kernel.org/r/20200311171422.10484-1-david@redhat.com Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Eric Blake <eblake@redhat.com> Cc: Markus Armbruster <armbru@redhat.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Igor Mammedov <imammedo@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Message-Id: <20200626072248.78761-11-david@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2020-06-26 10:22:37 +03:00
/*
* Virtio MEM device
*
* Copyright (C) 2020 Red Hat, Inc.
*
* Authors:
* David Hildenbrand <david@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2.
* See the COPYING file in the top-level directory.
*/
#ifndef HW_VIRTIO_MEM_H
#define HW_VIRTIO_MEM_H
#include "standard-headers/linux/virtio_mem.h"
#include "hw/virtio/virtio.h"
#include "qapi/qapi-types-misc.h"
#include "sysemu/hostmem.h"
#define TYPE_VIRTIO_MEM "virtio-mem"
#define VIRTIO_MEM(obj) \
OBJECT_CHECK(VirtIOMEM, (obj), TYPE_VIRTIO_MEM)
#define VIRTIO_MEM_CLASS(oc) \
OBJECT_CLASS_CHECK(VirtIOMEMClass, (oc), TYPE_VIRTIO_MEM)
#define VIRTIO_MEM_GET_CLASS(obj) \
OBJECT_GET_CLASS(VirtIOMEMClass, (obj), TYPE_VIRTIO_MEM)
#define VIRTIO_MEM_MEMDEV_PROP "memdev"
#define VIRTIO_MEM_NODE_PROP "node"
#define VIRTIO_MEM_SIZE_PROP "size"
#define VIRTIO_MEM_REQUESTED_SIZE_PROP "requested-size"
#define VIRTIO_MEM_BLOCK_SIZE_PROP "block-size"
#define VIRTIO_MEM_ADDR_PROP "memaddr"
typedef struct VirtIOMEM {
VirtIODevice parent_obj;
/* guest -> host request queue */
VirtQueue *vq;
/* bitmap used to track unplugged memory */
int32_t bitmap_size;
unsigned long *bitmap;
/* assigned memory backend and memory region */
HostMemoryBackend *memdev;
/* NUMA node */
uint32_t node;
/* assigned address of the region in guest physical memory */
uint64_t addr;
/* usable region size (<= region_size) */
uint64_t usable_region_size;
/* actual size (how much the guest plugged) */
uint64_t size;
/* requested size */
uint64_t requested_size;
/* block size and alignment */
uint64_t block_size;
/* notifiers to notify when "size" changes */
NotifierList size_change_notifiers;
virtio-mem: Paravirtualized memory hot(un)plug This is the very basic/initial version of virtio-mem. An introduction to virtio-mem can be found in the Linux kernel driver [1]. While it can be used in the current state for hotplug of a smaller amount of memory, it will heavily benefit from resizeable memory regions in the future. Each virtio-mem device manages a memory region (provided via a memory backend). After requested by the hypervisor ("requested-size"), the guest can try to plug/unplug blocks of memory within that region, in order to reach the requested size. Initially, and after a reboot, all memory is unplugged (except in special cases - reboot during postcopy). The guest may only try to plug/unplug blocks of memory within the usable region size. The usable region size is a little bigger than the requested size, to give the device driver some flexibility. The usable region size will only grow, except on reboots or when all memory is requested to get unplugged. The guest can never plug more memory than requested. Unplugged memory will get zapped/discarded, similar to in a balloon device. The block size is variable, however, it is always chosen in a way such that THP splits are avoided (e.g., 2MB). The state of each block (plugged/unplugged) is tracked in a bitmap. As virtio-mem devices (e.g., virtio-mem-pci) will be memory devices, we now expose "VirtioMEMDeviceInfo" via "query-memory-devices". -------------------------------------------------------------------------- There are two important follow-up items that are in the works: 1. Resizeable memory regions: Use resizeable allocations/RAM blocks to grow/shrink along with the usable region size. This avoids creating initially very big VMAs, RAM blocks, and KVM slots. 2. Protection of unplugged memory: Make sure the gust cannot actually make use of unplugged memory. Other follow-up items that are in the works: 1. Exclude unplugged memory during migration (via precopy notifier). 2. Handle remapping of memory. 3. Support for other architectures. -------------------------------------------------------------------------- Example usage (virtio-mem-pci is introduced in follow-up patches): Start QEMU with two virtio-mem devices (one per NUMA node): $ qemu-system-x86_64 -m 4G,maxmem=20G \ -smp sockets=2,cores=2 \ -numa node,nodeid=0,cpus=0-1 -numa node,nodeid=1,cpus=2-3 \ [...] -object memory-backend-ram,id=mem0,size=8G \ -device virtio-mem-pci,id=vm0,memdev=mem0,node=0,requested-size=0M \ -object memory-backend-ram,id=mem1,size=8G \ -device virtio-mem-pci,id=vm1,memdev=mem1,node=1,requested-size=1G Query the configuration: (qemu) info memory-devices Memory device [virtio-mem]: "vm0" memaddr: 0x140000000 node: 0 requested-size: 0 size: 0 max-size: 8589934592 block-size: 2097152 memdev: /objects/mem0 Memory device [virtio-mem]: "vm1" memaddr: 0x340000000 node: 1 requested-size: 1073741824 size: 1073741824 max-size: 8589934592 block-size: 2097152 memdev: /objects/mem1 Add some memory to node 0: (qemu) qom-set vm0 requested-size 500M Remove some memory from node 1: (qemu) qom-set vm1 requested-size 200M Query the configuration again: (qemu) info memory-devices Memory device [virtio-mem]: "vm0" memaddr: 0x140000000 node: 0 requested-size: 524288000 size: 524288000 max-size: 8589934592 block-size: 2097152 memdev: /objects/mem0 Memory device [virtio-mem]: "vm1" memaddr: 0x340000000 node: 1 requested-size: 209715200 size: 209715200 max-size: 8589934592 block-size: 2097152 memdev: /objects/mem1 [1] https://lkml.kernel.org/r/20200311171422.10484-1-david@redhat.com Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Eric Blake <eblake@redhat.com> Cc: Markus Armbruster <armbru@redhat.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Igor Mammedov <imammedo@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Message-Id: <20200626072248.78761-11-david@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2020-06-26 10:22:37 +03:00
} VirtIOMEM;
typedef struct VirtIOMEMClass {
/* private */
VirtIODevice parent;
/* public */
void (*fill_device_info)(const VirtIOMEM *vmen, VirtioMEMDeviceInfo *vi);
MemoryRegion *(*get_memory_region)(VirtIOMEM *vmem, Error **errp);
void (*add_size_change_notifier)(VirtIOMEM *vmem, Notifier *notifier);
void (*remove_size_change_notifier)(VirtIOMEM *vmem, Notifier *notifier);
virtio-mem: Paravirtualized memory hot(un)plug This is the very basic/initial version of virtio-mem. An introduction to virtio-mem can be found in the Linux kernel driver [1]. While it can be used in the current state for hotplug of a smaller amount of memory, it will heavily benefit from resizeable memory regions in the future. Each virtio-mem device manages a memory region (provided via a memory backend). After requested by the hypervisor ("requested-size"), the guest can try to plug/unplug blocks of memory within that region, in order to reach the requested size. Initially, and after a reboot, all memory is unplugged (except in special cases - reboot during postcopy). The guest may only try to plug/unplug blocks of memory within the usable region size. The usable region size is a little bigger than the requested size, to give the device driver some flexibility. The usable region size will only grow, except on reboots or when all memory is requested to get unplugged. The guest can never plug more memory than requested. Unplugged memory will get zapped/discarded, similar to in a balloon device. The block size is variable, however, it is always chosen in a way such that THP splits are avoided (e.g., 2MB). The state of each block (plugged/unplugged) is tracked in a bitmap. As virtio-mem devices (e.g., virtio-mem-pci) will be memory devices, we now expose "VirtioMEMDeviceInfo" via "query-memory-devices". -------------------------------------------------------------------------- There are two important follow-up items that are in the works: 1. Resizeable memory regions: Use resizeable allocations/RAM blocks to grow/shrink along with the usable region size. This avoids creating initially very big VMAs, RAM blocks, and KVM slots. 2. Protection of unplugged memory: Make sure the gust cannot actually make use of unplugged memory. Other follow-up items that are in the works: 1. Exclude unplugged memory during migration (via precopy notifier). 2. Handle remapping of memory. 3. Support for other architectures. -------------------------------------------------------------------------- Example usage (virtio-mem-pci is introduced in follow-up patches): Start QEMU with two virtio-mem devices (one per NUMA node): $ qemu-system-x86_64 -m 4G,maxmem=20G \ -smp sockets=2,cores=2 \ -numa node,nodeid=0,cpus=0-1 -numa node,nodeid=1,cpus=2-3 \ [...] -object memory-backend-ram,id=mem0,size=8G \ -device virtio-mem-pci,id=vm0,memdev=mem0,node=0,requested-size=0M \ -object memory-backend-ram,id=mem1,size=8G \ -device virtio-mem-pci,id=vm1,memdev=mem1,node=1,requested-size=1G Query the configuration: (qemu) info memory-devices Memory device [virtio-mem]: "vm0" memaddr: 0x140000000 node: 0 requested-size: 0 size: 0 max-size: 8589934592 block-size: 2097152 memdev: /objects/mem0 Memory device [virtio-mem]: "vm1" memaddr: 0x340000000 node: 1 requested-size: 1073741824 size: 1073741824 max-size: 8589934592 block-size: 2097152 memdev: /objects/mem1 Add some memory to node 0: (qemu) qom-set vm0 requested-size 500M Remove some memory from node 1: (qemu) qom-set vm1 requested-size 200M Query the configuration again: (qemu) info memory-devices Memory device [virtio-mem]: "vm0" memaddr: 0x140000000 node: 0 requested-size: 524288000 size: 524288000 max-size: 8589934592 block-size: 2097152 memdev: /objects/mem0 Memory device [virtio-mem]: "vm1" memaddr: 0x340000000 node: 1 requested-size: 209715200 size: 209715200 max-size: 8589934592 block-size: 2097152 memdev: /objects/mem1 [1] https://lkml.kernel.org/r/20200311171422.10484-1-david@redhat.com Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Eric Blake <eblake@redhat.com> Cc: Markus Armbruster <armbru@redhat.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Igor Mammedov <imammedo@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Message-Id: <20200626072248.78761-11-david@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2020-06-26 10:22:37 +03:00
} VirtIOMEMClass;
#endif