[Qemu-devel] [RFC v2 0/6] QEMU shared-memory backend

[Baptiste Reynal]

A new memory backend, the shared memory backend, based on
the file memory backend.

This new backend allows a master QEMU instance to share a part of
his main memory whith a slave QEMU instance. It is then possible to load
a firmware on this memory and trigger the slave boot using a SDM
signal.

Such new backend enables, on a master side, to allocate the whole
memory as shareable (e.g. /dev/shm, or hugetlbfs).
On the slave side it enables the startup of QEMU without any main memory
allocated. Then the slave goes in a waiting state, the same used in the
case of an incoming migration, and the file descriptor of the shared
memory is sent by the master over a socket.
The waiting state ends when the master sends to the slave a signal
with size and offset to mmap and use as memory as payload.

You can test those patches using modules and test application available
on https://git.virtualopensystems.com/dev/qemu-het-tools.
- SDM Platform module on branch sdm_test_mod_v1
- Test application on branch sdm_test_app
- Slave files on branch demo_slaves_sdm

 QEMU code is avalaible here https://git.virtualopensystems.com/dev/qemu on 
branch rfc_v2.

Run QEMU master instance:
./qemu-system-arm -nographic \
        -kernel zImage \
        -M virt -m 1G \
        -initrd busybox.cpio \
        -object multi-socket-backend,id=sock,path=sock,listen \
        -object 
memory-backend-shared,id=mem,size=1G,mem-path=/dev/hugepages,socket=sock,master 
\
        -object sdm-signal-shboot,id=boot,shm=mem \
        -object sdm-communication-socket,id=scomm,socket=sock \
        -device 
virtio-sdm-device,comm=scomm,master,num-slaves=1,len-signals=1,signals[0]=boot \
        -append "mem=512M memmap=512M$0x60000000" \
        -numa node,memdev=mem -m 1G

Run QEMU slave instance:
./qemu-system-arm -nographic \
        -kernel zImage \
        -M virt -m 1G \
        -initrd busybox.cpio \
        -object multi-socket-backend,id=sock,path=sock \
        -object memory-backend-shared,id=mem,size=512M,socket=sock \
        -object sdm-signal-shboot,id=boot,shm=mem \
        -object sdm-communication-socket,id=scomm,socket=sock \
        -device sdm-platform,comm=scomm,len-signals=1,signals[0]="boot" \
        -incoming "shared:mem" \
        -numa node,memdev=mem -m 512M

On the master, load the SDM module (insmod sdm_test_mod_v1) and trigger the 
boot with
the following command:
./sdm-test -b 0 1 zImage slave.dtb

zImage and slave.dtb are available on branch demo_slaves_sdm.

This patch serie is a follow-up to "[RFC PATCH 0/8] Towards an Heterogeneous 
QEMU":
https://lists.gnu.org/archive/html/qemu-devel/2015-10/msg00171.html

This patch serie depends on:
- [RFC v2 0/6] SDM Interface
- [RFC v2 1/1] backend: multi-client-socket

This work has been sponsored by Huawei Technologies Duesseldorf GmbH.

Baptiste Reynal (3):
  backend: shared memory backend
  migration: add shared migration type
  hw/misc: sdm signal shboot

Christian Pinto (3):
  qemu: slave machine flag
  hw/arm: boot
  qemu: numa

 backends/Makefile.objs              |   2 +-
 backends/hostmem-shared.c           | 198 ++++++++++++++++++++++++++++++++++++
 hw/arm/boot.c                       |  13 +++
 hw/core/machine.c                   |  27 +++++
 hw/misc/Makefile.objs               |   1 +
 hw/misc/sdm-signal-shboot.c         |  62 +++++++++++
 include/hw/boards.h                 |   2 +
 include/hw/misc/sdm-signal-shboot.h |  38 +++++++
 include/migration/migration.h       |   2 +
 include/sysemu/hostmem-shared.h     |  66 ++++++++++++
 migration/Makefile.objs             |   2 +-
 migration/migration.c               |   2 +
 migration/shared.c                  |  33 ++++++
 numa.c                              |  17 +++-
 qemu-options.hx                     |   5 +-
 util/qemu-config.c                  |   5 +
 16 files changed, 471 insertions(+), 4 deletions(-)
 create mode 100644 backends/hostmem-shared.c
 create mode 100644 hw/misc/sdm-signal-shboot.c
 create mode 100644 include/hw/misc/sdm-signal-shboot.h
 create mode 100644 include/sysemu/hostmem-shared.h
 create mode 100644 migration/shared.c

-- 
2.7.3