From: Peter Maydell Date: Thu, 12 Nov 2020 14:40:34 +0000 (+0000) Subject: docs: Move cpu-hotplug.rst into the system manual X-Git-Tag: v5.2.0~15^2~7 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=392d8e95c7dd3de10a20387914ac34cb12d8ff04;p=mirror_qemu.git docs: Move cpu-hotplug.rst into the system manual The cpu-hotplug.rst documentation is currently orphan and not included in any manual; move it into the system manual. Signed-off-by: Peter Maydell Reviewed-by: Alex Bennée --- diff --git a/docs/cpu-hotplug.rst b/docs/cpu-hotplug.rst deleted file mode 100644 index d0b06403f1..0000000000 --- a/docs/cpu-hotplug.rst +++ /dev/null @@ -1,142 +0,0 @@ -=================== -Virtual CPU hotplug -=================== - -A complete example of vCPU hotplug (and hot-unplug) using QMP -``device_add`` and ``device_del``. - -vCPU hotplug ------------- - -(1) Launch QEMU as follows (note that the "maxcpus" is mandatory to - allow vCPU hotplug):: - - $ qemu-system-x86_64 -display none -no-user-config -m 2048 \ - -nodefaults -monitor stdio -machine pc,accel=kvm,usb=off \ - -smp 1,maxcpus=2 -cpu IvyBridge-IBRS \ - -qmp unix:/tmp/qmp-sock,server,nowait - -(2) Run 'qmp-shell' (located in the source tree, under: "scripts/qmp/) - to connect to the just-launched QEMU:: - - $> ./qmp-shell -p -v /tmp/qmp-sock - [...] - (QEMU) - -(3) Find out which CPU types could be plugged, and into which sockets:: - - (QEMU) query-hotpluggable-cpus - { - "execute": "query-hotpluggable-cpus", - "arguments": {} - } - { - "return": [ - { - "type": "IvyBridge-IBRS-x86_64-cpu", - "vcpus-count": 1, - "props": { - "socket-id": 1, - "core-id": 0, - "thread-id": 0 - } - }, - { - "qom-path": "/machine/unattached/device[0]", - "type": "IvyBridge-IBRS-x86_64-cpu", - "vcpus-count": 1, - "props": { - "socket-id": 0, - "core-id": 0, - "thread-id": 0 - } - } - ] - } - (QEMU) - -(4) The ``query-hotpluggable-cpus`` command returns an object for CPUs - that are present (containing a "qom-path" member) or which may be - hot-plugged (no "qom-path" member). From its output in step (3), we - can see that ``IvyBridge-IBRS-x86_64-cpu`` is present in socket 0, - while hot-plugging a CPU into socket 1 requires passing the listed - properties to QMP ``device_add``:: - - (QEMU) device_add id=cpu-2 driver=IvyBridge-IBRS-x86_64-cpu socket-id=1 core-id=0 thread-id=0 - { - "execute": "device_add", - "arguments": { - "socket-id": 1, - "driver": "IvyBridge-IBRS-x86_64-cpu", - "id": "cpu-2", - "core-id": 0, - "thread-id": 0 - } - } - { - "return": {} - } - (QEMU) - -(5) Optionally, run QMP `query-cpus-fast` for some details about the - vCPUs:: - - (QEMU) query-cpus-fast - { - "execute": "query-cpus-fast", - "arguments": {} - } - { - "return": [ - { - "qom-path": "/machine/unattached/device[0]", - "target": "x86_64", - "thread-id": 11534, - "cpu-index": 0, - "props": { - "socket-id": 0, - "core-id": 0, - "thread-id": 0 - }, - "arch": "x86" - }, - { - "qom-path": "/machine/peripheral/cpu-2", - "target": "x86_64", - "thread-id": 12106, - "cpu-index": 1, - "props": { - "socket-id": 1, - "core-id": 0, - "thread-id": 0 - }, - "arch": "x86" - } - ] - } - (QEMU) - -vCPU hot-unplug ---------------- - -From the 'qmp-shell', invoke the QMP ``device_del`` command:: - - (QEMU) device_del id=cpu-2 - { - "execute": "device_del", - "arguments": { - "id": "cpu-2" - } - } - { - "return": {} - } - (QEMU) - -.. note:: - vCPU hot-unplug requires guest cooperation; so the ``device_del`` - command above does not guarantee vCPU removal -- it's a "request to - unplug". At this point, the guest will get a System Control - Interrupt (SCI) and calls the ACPI handler for the affected vCPU - device. Then the guest kernel will bring the vCPU offline and tell - QEMU to unplug it. diff --git a/docs/system/cpu-hotplug.rst b/docs/system/cpu-hotplug.rst new file mode 100644 index 0000000000..d0b06403f1 --- /dev/null +++ b/docs/system/cpu-hotplug.rst @@ -0,0 +1,142 @@ +=================== +Virtual CPU hotplug +=================== + +A complete example of vCPU hotplug (and hot-unplug) using QMP +``device_add`` and ``device_del``. + +vCPU hotplug +------------ + +(1) Launch QEMU as follows (note that the "maxcpus" is mandatory to + allow vCPU hotplug):: + + $ qemu-system-x86_64 -display none -no-user-config -m 2048 \ + -nodefaults -monitor stdio -machine pc,accel=kvm,usb=off \ + -smp 1,maxcpus=2 -cpu IvyBridge-IBRS \ + -qmp unix:/tmp/qmp-sock,server,nowait + +(2) Run 'qmp-shell' (located in the source tree, under: "scripts/qmp/) + to connect to the just-launched QEMU:: + + $> ./qmp-shell -p -v /tmp/qmp-sock + [...] + (QEMU) + +(3) Find out which CPU types could be plugged, and into which sockets:: + + (QEMU) query-hotpluggable-cpus + { + "execute": "query-hotpluggable-cpus", + "arguments": {} + } + { + "return": [ + { + "type": "IvyBridge-IBRS-x86_64-cpu", + "vcpus-count": 1, + "props": { + "socket-id": 1, + "core-id": 0, + "thread-id": 0 + } + }, + { + "qom-path": "/machine/unattached/device[0]", + "type": "IvyBridge-IBRS-x86_64-cpu", + "vcpus-count": 1, + "props": { + "socket-id": 0, + "core-id": 0, + "thread-id": 0 + } + } + ] + } + (QEMU) + +(4) The ``query-hotpluggable-cpus`` command returns an object for CPUs + that are present (containing a "qom-path" member) or which may be + hot-plugged (no "qom-path" member). From its output in step (3), we + can see that ``IvyBridge-IBRS-x86_64-cpu`` is present in socket 0, + while hot-plugging a CPU into socket 1 requires passing the listed + properties to QMP ``device_add``:: + + (QEMU) device_add id=cpu-2 driver=IvyBridge-IBRS-x86_64-cpu socket-id=1 core-id=0 thread-id=0 + { + "execute": "device_add", + "arguments": { + "socket-id": 1, + "driver": "IvyBridge-IBRS-x86_64-cpu", + "id": "cpu-2", + "core-id": 0, + "thread-id": 0 + } + } + { + "return": {} + } + (QEMU) + +(5) Optionally, run QMP `query-cpus-fast` for some details about the + vCPUs:: + + (QEMU) query-cpus-fast + { + "execute": "query-cpus-fast", + "arguments": {} + } + { + "return": [ + { + "qom-path": "/machine/unattached/device[0]", + "target": "x86_64", + "thread-id": 11534, + "cpu-index": 0, + "props": { + "socket-id": 0, + "core-id": 0, + "thread-id": 0 + }, + "arch": "x86" + }, + { + "qom-path": "/machine/peripheral/cpu-2", + "target": "x86_64", + "thread-id": 12106, + "cpu-index": 1, + "props": { + "socket-id": 1, + "core-id": 0, + "thread-id": 0 + }, + "arch": "x86" + } + ] + } + (QEMU) + +vCPU hot-unplug +--------------- + +From the 'qmp-shell', invoke the QMP ``device_del`` command:: + + (QEMU) device_del id=cpu-2 + { + "execute": "device_del", + "arguments": { + "id": "cpu-2" + } + } + { + "return": {} + } + (QEMU) + +.. note:: + vCPU hot-unplug requires guest cooperation; so the ``device_del`` + command above does not guarantee vCPU removal -- it's a "request to + unplug". At this point, the guest will get a System Control + Interrupt (SCI) and calls the ACPI handler for the affected vCPU + device. Then the guest kernel will bring the vCPU offline and tell + QEMU to unplug it. diff --git a/docs/system/index.rst b/docs/system/index.rst index d0613cd5f7..0f0f6d2e99 100644 --- a/docs/system/index.rst +++ b/docs/system/index.rst @@ -29,6 +29,7 @@ Contents: tls gdb managed-startup + cpu-hotplug targets security deprecated