mirror of
https://github.com/Motorhead1991/qemu.git
synced 2025-12-21 15:08:36 -07:00
aa910c20ec
Let's add our virtio-mem-ccw proxy device and wire it up. We should
be supporting everything (e.g., device unplug, "dynamic-memslots") that
we already support for the virtio-pci variant.
With a Linux guest that supports virtio-mem (and has automatic memory
onlining properly configured) the following example will work:
1. Start a VM with 4G initial memory and a virtio-mem device with a maximum
capacity of 16GB:
qemu/build/qemu-system-s390x \
--enable-kvm \
-m 4G,maxmem=20G \
-nographic \
-smp 8 \
-hda Fedora-Server-KVM-40-1.14.s390x.qcow2 \
-chardev socket,id=monitor,path=/var/tmp/monitor,server,nowait \
-mon chardev=monitor,mode=readline \
-object memory-backend-ram,id=mem0,size=16G,reserve=off \
-device virtio-mem-ccw,id=vmem0,memdev=mem0,dynamic-memslots=on
2. Query the current size of virtio-mem device:
(qemu) info memory-devices
Memory device [virtio-mem]: "vmem0"
memaddr: 0x100000000
node: 0
requested-size: 0
size: 0
max-size: 17179869184
block-size: 1048576
memdev: /objects/mem0
3. Request to grow it to 8GB (hotplug 8GB):
(qemu) qom-set vmem0 requested-size 8G
(qemu) info memory-devices
Memory device [virtio-mem]: "vmem0"
memaddr: 0x100000000
node: 0
requested-size: 8589934592
size: 8589934592
max-size: 17179869184
block-size: 1048576
memdev: /objects/mem0
4. Request to grow to 16GB (hotplug another 8GB):
(qemu) qom-set vmem0 requested-size 16G
(qemu) info memory-devices
Memory device [virtio-mem]: "vmem0"
memaddr: 0x100000000
node: 0
requested-size: 17179869184
size: 17179869184
max-size: 17179869184
block-size: 1048576
memdev: /objects/mem0
5. Try to hotunplug all memory again, shrinking to 0GB:
(qemu) qom-set vmem0 requested-size 0G
(qemu) info memory-devices
Memory device [virtio-mem]: "vmem0"
memaddr: 0x100000000
node: 0
requested-size: 0
size: 0
max-size: 17179869184
block-size: 1048576
memdev: /objects/mem0
6. If it worked, unplug the device
(qemu) device_del vmem0
(qemu) info memory-devices
(qemu) object_del mem0
7. Hotplug a new device with a smaller capacity and directly size it to 1GB
(qemu) object_add memory-backend-ram,id=mem0,size=8G,reserve=off
(qemu) device_add virtio-mem-ccw,id=vmem0,memdev=mem0,\
dynamic-memslots=on,requested-size=1G
(qemu) info memory-devices
Memory device [virtio-mem]: "vmem0"
memaddr: 0x100000000
node: 0
requested-size: 1073741824
size: 1073741824
max-size: 8589934592
block-size: 1048576
memdev: /objects/mem0
Trying to use a virtio-mem device backed by hugetlb into a !hugetlb VM
correctly results in the error:
... Memory device uses a bigger page size than initial memory
Note that the virtio-mem driver in Linux will supports 1 MiB (pageblock)
granularity.
Message-ID: <20241219144115.2820241-15-david@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
|
||
|---|---|---|
| .. | ||
| 9pfs | ||
| acpi | ||
| adc | ||
| alpha | ||
| arm | ||
| audio | ||
| avr | ||
| block | ||
| char | ||
| core | ||
| cpu | ||
| cxl | ||
| display | ||
| dma | ||
| fsi | ||
| gpio | ||
| hppa | ||
| hyperv | ||
| i2c | ||
| i386 | ||
| ide | ||
| input | ||
| intc | ||
| ipack | ||
| ipmi | ||
| isa | ||
| loongarch | ||
| m68k | ||
| mem | ||
| microblaze | ||
| mips | ||
| misc | ||
| net | ||
| nubus | ||
| nvme | ||
| nvram | ||
| openrisc | ||
| pci | ||
| pci-bridge | ||
| pci-host | ||
| ppc | ||
| remote | ||
| riscv | ||
| rtc | ||
| rx | ||
| s390x | ||
| scsi | ||
| sd | ||
| sensor | ||
| sh4 | ||
| smbios | ||
| sparc | ||
| sparc64 | ||
| ssi | ||
| timer | ||
| tpm | ||
| tricore | ||
| ufs | ||
| usb | ||
| vfio | ||
| virtio | ||
| watchdog | ||
| xen | ||
| xenpv | ||
| xtensa | ||
| Kconfig | ||
| meson.build | ||