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>
The virtio-iommu device attaches itself to a PCI bus, so it makes
no sense to include it unless PCI is supported---and in fact
compilation fails without this change.
Reported-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This patchs adds the skeleton for the virtio-iommu device.
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20200214132745.23392-2-eric.auger@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This is the implementation of virtio-pmem device. Support will require
machine changes for the architectures that will support it, so it will
not yet be compiled. It can be unlocked with VIRTIO_PMEM_SUPPORTED per
machine and disabled globally via VIRTIO_PMEM.
We cannot use the "addr" property as that is already used e.g. for
virtio-pci/pci devices. And we will have e.g. virtio-pmem-pci as a proxy.
So we have to choose a different one (unfortunately). "memaddr" it is.
That name should ideally be used by all other virtio-* based memory
devices in the future.
-device virtio-pmem-pci,id=p0,bus=bux0,addr=0x01,memaddr=0x1000000...
Acked-by: Markus Armbruster <armbru@redhat.com>
[ QAPI bits ]
Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
[ MemoryDevice/MemoryRegion changes, cleanups, addr property "memaddr",
split up patches, unplug handler ]
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20190619094907.10131-2-pagupta@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Instead of hard-coding all config switches in the config file
default-configs/s390x-softmmu.mak, let's use the new Kconfig files
to express the necessary dependencies: The S390_CCW_VIRTIO config switch
for the "s390-ccw-virtio" machine now selects all non-optional devices.
And since we already have the VIRTIO_PCI and VIRTIO_MMIO config switches
for the other two virtio transports, this patch also introduces a new
config switch VIRTIO_CCW for the third, s390x-specific virtio transport,
so that all three virtio transports are now handled in the same way.
Signed-off-by: Thomas Huth <thuth@redhat.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20190123065618.3520-42-yang.zhong@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Instead of including the same list of devices for each target,
set CONFIG_PCI to true, and make the devices default to present
whenever PCI is available. However, s390x does not want all the
PCI devices, so there is a separate symbol to enable them.
Done mostly with the following script:
while read i; do
i=${i%=y}; i=${i#CONFIG_}
sed -i -e'/^config '$i'$/!b' -en \
-e'a\' -e' default y if PCI_DEVICES\' -e' depends on PCI' \
`grep -lw $i hw/*/Kconfig`
done < default-configs/pci.mak
followed by replacing a few "depends on" clauses with "select"
whenever the symbol is not really related to PCI.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20190123065618.3520-31-yang.zhong@intel.com>
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The Kconfig files were generated mostly with this script:
for i in `grep -ho CONFIG_[A-Z0-9_]* default-configs/* | sort -u`; do
set fnord `git grep -lw $i -- 'hw/*/Makefile.objs' `
shift
if test $# = 1; then
cat >> $(dirname $1)/Kconfig << EOF
config ${i#CONFIG_}
bool
EOF
git add $(dirname $1)/Kconfig
else
echo $i $*
fi
done
sed -i '$d' hw/*/Kconfig
for i in hw/*; do
if test -d $i && ! test -f $i/Kconfig; then
touch $i/Kconfig
git add $i/Kconfig
fi
done
Whenever a symbol is referenced from multiple subdirectories, the
script prints the list of directories that reference the symbol.
These symbols have to be added manually to the Kconfig files.
Kconfig.host and hw/Kconfig were created manually.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
Message-Id: <20190123065618.3520-27-yang.zhong@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
