[PATCH v8 20/20] multi-process: add configure and usage information

[Jagannathan Raman <jag.raman@oracle.com>]

From: Elena Ufimtseva <elena.ufimtseva@oracle.com>

Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
---
 MAINTAINERS                |  2 ++
 docs/multi-process.rst     | 67 ++++++++++++++++++++++++++++++++++++++++++++++
 scripts/mpqemu-launcher.py | 49 +++++++++++++++++++++++++++++++++
 3 files changed, 118 insertions(+)
 create mode 100644 docs/multi-process.rst
 create mode 100755 scripts/mpqemu-launcher.py

diff --git a/MAINTAINERS b/MAINTAINERS
index f41b54c..3df9441 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3058,6 +3058,8 @@ F: include/hw/pci/memory-sync.h
 F: hw/remote/iohub.c
 F: include/hw/remote/iohub.h
 F: docs/devel/multi-process.rst
+F: scripts/mpqemu-launcher.py
+F: scripts/mpqemu-launcher-perf-mode.py
 
 Build and test automation
 -------------------------
diff --git a/docs/multi-process.rst b/docs/multi-process.rst
new file mode 100644
index 0000000..9dc55e3
--- /dev/null
+++ b/docs/multi-process.rst
@@ -0,0 +1,67 @@
+Multi-process QEMU
+==================
+
+This document describes how to configure and use multi-process qemu.
+For the design document refer to docs/devel/qemu-multiprocess.
+
+1) Configuration
+----------------
+
+To enable support for multi-process add --enable-mpqemu
+to the list of options for the "configure" script.
+
+
+2) Usage
+--------
+
+Multi-process QEMU requires an orchestrator to launch. Please refer to a
+light-weight python based orchestrator for mpqemu in
+scripts/mpqemu-launcher.py to lauch QEMU in multi-process mode.
+
+Following is a description of command-line used to launch mpqemu.
+
+* Orchestrator:
+
+  - The Orchestrator creates a unix socketpair
+
+  - It launches the remote process and passes one of the
+    sockets to it via command-line.
+
+  - It then launches QEMU and specifies the other socket as an option
+    to the Proxy device object
+
+* Remote Process:
+
+  - QEMU can enter remote process mode by using the "remote" machine
+    option.
+
+  - The orchestrator creates a "remote-object" with details about
+    the device and the file descriptor for the device
+
+  - The remaining options are no different from how one launches QEMU with
+    devices.
+
+  - Example command-line for the remote process is as follows:
+
+      /usr/bin/qemu-system-x86_64                                        \
+      -machine remote                                                    \
+      -device lsi53c895a,id=lsi0                                         \
+      -drive id=drive_image2,file=/build/ol7-nvme-test-1.qcow2           \
+      -device scsi-hd,id=drive2,drive=drive_image2,bus=lsi0.0,scsi-id=0  \
+      -object remote-object,id=robj1,devid=lsi1,fd=4,
+
+* QEMU:
+
+  - Since parts of the RAM are shared between QEMU & remote process, a
+    memory-backend-memfd is required to facilitate this, as follows:
+
+    -object memory-backend-memfd,id=mem,size=2G
+
+  - A "pci-proxy-dev" device is created for each of the PCI devices emulated
+    in the remote process. A "socket" sub-option specifies the other end of
+    unix channel created by orchestrator. The "id" sub-option must be specified
+    and should be the same as the "id" specified for the remote PCI device
+
+  - Example commandline for QEMU is as follows:
+
+      -device pci-proxy-dev,id=lsi0,socket=3
diff --git a/scripts/mpqemu-launcher.py b/scripts/mpqemu-launcher.py
new file mode 100755
index 0000000..07b11c6
--- /dev/null
+++ b/scripts/mpqemu-launcher.py
@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+import socket
+import os
+import subprocess
+import time
+
+PROC_QEMU='/usr/bin/qemu-system-x86_64'
+
+proxy, remote = socket.socketpair(socket.AF_UNIX, socket.SOCK_STREAM)
+
+remote_cmd = [ PROC_QEMU,                                                     \
+               '-machine', 'remote',                                          \
+               '-device', 'lsi53c895a,id=lsi1',                               \
+               '-drive', 'id=drive_image1,file=/build/ol7-nvme-test-1.qcow2', \
+               '-device', 'scsi-hd,id=drive1,drive=drive_image1,bus=lsi1.0,'  \
+                              'scsi-id=0',                                    \
+               '-object',                                                     \
+               'remote-object,id=robj1,devid=lsi1,fd='+str(remote.fileno()),  \
+               '-nographic',                                                  \
+             ]
+
+proxy_cmd = [ PROC_QEMU,                                                      \
+              '-name', 'OL7.4',                                               \
+              '-machine', 'q35,accel=kvm',                                    \
+              '-smp', 'sockets=1,cores=1,threads=1',                          \
+              '-m', '2048',                                                   \
+              '-object', 'memory-backend-memfd,id=sysmem-file,size=2G',       \
+              '-numa', 'node,memdev=sysmem-file',                             \
+              '-device', 'virtio-scsi-pci,id=virtio_scsi_pci0',               \
+              '-drive', 'id=drive_image1,if=none,format=qcow2,'               \
+                            'file=/home/ol7-hdd-1.qcow2',                     \
+              '-device', 'scsi-hd,id=image1,drive=drive_image1,'              \
+                             'bus=virtio_scsi_pci0.0',                        \
+              '-boot', 'd',                                                   \
+              '-vnc', ':0',                                                   \
+              '-device', 'pci-proxy-dev,id=lsi1,fd='+str(proxy.fileno()),     \
+            ]
+
+
+pid = os.fork();
+
+if pid:
+    # In Proxy
+    print('Launching QEMU with Proxy object');
+    process = subprocess.Popen(proxy_cmd, pass_fds=[proxy.fileno()])
+else:
+    # In remote
+    print('Launching Remote process');
+    process = subprocess.Popen(remote_cmd, pass_fds=[remote.fileno()])
-- 
1.8.3.1