The KVM introspection subsystem provides a facility for applications
running on the host or in a separate VM, to control the execution of
other VMs (pause, resume, shutdown), query the state of the vCPUs (GPRs,
MSRs etc.), alter the page access bits in the shadow page tables (only
for the hardware backed ones, eg. Intel's EPT) and receive notifications
when events of interest have taken place (shadow page table level faults,
key MSR writes, hypercalls etc.).
This is the userspace part of the KVM introspection API already posted
on the KVM list[1]. Thanks to Samuel Laurén and Mathieu Tarral, this
new VMI API has been integrated into the KVM-VMI[2] project. The pull
request into the libVMI[3] library is under review.
As suggested by Stefan Hajnoczi and Paolo Bonzini, the connection with the
introspection tool is initiated by the QEMU process of the introspected VM
using a socket. After the handshake, QEMU will hand over the file
descriptor to KVM. From this point, the introspection tool will use
the socket to send introspection commands (read/write guest memory, set
page access, etc.) directly to KVM and to receive introspection events
(breakpoint, page fault, etc.). However, for some user actions such
as pause, suspend, live migration, etc., we rely on QEMU to notify KVM,
that will notify the introspection tool, to remove the changes made to
the guest, so that the guest can run when the introspection channel
is disconnected.
The patches were tested with QEMU 2.12 (through libvirt 1.3.1) and
summarly tested with 5.0.0-rc2, except for the last two patches (25
and 26) which were not tested at all, but still included for the initial
feedback.
Patches 01-06 add some extensions to the current code, which may or
may not be needed for the next patches, but we're looking forward for your
comments about these. Except for patch 6, all are chardev/socket related.
Patch 07 adds the KVM ioctls for VM introspection:
- KVM_INTROSPECTION_HOOK used to hand over the file descriptor
- KVM_INTROSPETION_PREUNHOOK used on pause/suspend/live migration
- KVM_INTROSPECTION_UNHOOK used to clean-up the introspection structures
from KVM
- KVM_INTROSPECTION_COMMAND and KVM_INTROSPECTION_EVENT used to mark the
the introspection commands/events that are allowed.
Patch 08 and 09 introduce the newly added introspection object. Patch 08
contains the usage documenation of this object with all the parameters
that will be added by the next patches. We've tested the creation of
this object through QMP/libvirt and we rely on this to start the VM
introspection for any running VM.
Patches 10-12 add the handshake, the authentication of the introspection
tool and the hand over to KVM.
Patches 13-15 add some safe guards (block the destruction of the
introspection object if the introspection socket is connected and
allow only one instance of the introspection object) and force the
socket reconnection on guest reset. Blocking the destruction of the
introspection object might not be enough, because we also want to block
the destruction of the introspection socket. Or it might be too much,
because this can be done through QMP, and whoever has access to it
may crash the guest in multiple ways.
Patches 16-17 add the first intercepted commands (pause/resume) and
introduce one of the method we use to delay intercepted commands
until the introspection tool has a chance to react.
Patch 18 adds the information we save with the VM snapshot,
the VM start time.
Patches 19-20 add the interception of force-reset and live migration
commands.
Patch 21 adds an workaround to block the snapshots with memory done by
libvirt until the introspection tool has a chance to react. It hasn't
been tested with 5.0.0-rc2. For 2.12 the patch is slightly bigger.
Patch 22 adds a second method of delaying the intercepted commands,
by running the main loop.
Patches 23-24 add the interception of the shutdown command, which doesn't
seems to be done right because the shutdown signal might not be delivered
to the guest, not to mention that is desirable to catch all sources that
my trigger the shudown.
Patch 25, which is not tested, extends the handshake structures to send
the e820 table (for the x86* architectures).
Patch 26, adds the properties to control what introspection commands
and what introspection events are allowed for this guest.
[1]: https://lore.kernel.org/kvm/20200330101308.21702-1-ala...@bitdefender.com/
[2]: https://github.com/KVM-VMI/kvm-vmi
[3]: https://github.com/libvmi/libvmi
Adalbert Lazăr (20):
chardev: tcp: allow to change the reconnect timer
char-socket: allow vsock parameters (cid, port)
char-socket: fix the client mode when created through QMP
char-socket: add 'reconnecting' property
char-socket: add 'fd' property
E820: extend the table access interface
linux-headers: update with VM introspection interface
kvm: introduce the VM introspection object
kvm: vmi: add the handshake with the introspection tool
kvm: vmi: add 'handshake_timeout' property
kvm: vmi: add 'key' property
kvm: vmi: block the object destruction if the chardev is connected
kvm: vmi: allow only one instance of the introspection object
kvm: vmi: add 'unhook_timeout' property
kvm: vmi: store/restore 'vm_start_time' on migrate/snapshot
kvm: vmi: postpone the OK response from qmp_stop()
kvm: vmi: add 'async_unhook' property
kvm: vmi: add 'unhook_on_shutdown' property
kvm: vmi: extend handshake to include the e820 table
kvm: vmi: add 'command' and 'event' properties
Marian Rotariu (6):
kvm: add VM introspection usage documentation
kvm: vmi: reconnect the socket on reset
kvm: vmi: intercept pause/resume
kvm: vmi: intercept force-reset
kvm: vmi: intercept live migration
kvm: vmi: intercept shutdown
accel/kvm/Makefile.objs | 1 +
accel/kvm/vmi.c | 1091 ++++++++++++++++++++++++++++++++
accel/stubs/Makefile.objs | 1 +
accel/stubs/vmi-stubs.c | 14 +
chardev/char-fe.c | 11 +
chardev/char-socket.c | 72 ++-
chardev/char.c | 3 +
hw/i386/e820_memory_layout.c | 12 +
hw/i386/e820_memory_layout.h | 2 +
include/chardev/char-fe.h | 7 +
include/chardev/char.h | 1 +
include/monitor/monitor.h | 1 +
include/sysemu/vmi-handshake.h | 66 ++
include/sysemu/vmi-intercept.h | 25 +
linux-headers/linux/kvm.h | 20 +
migration/migration.c | 18 +-
migration/migration.h | 2 +
monitor/Makefile.objs | 2 +-
monitor/qmp-cmds.c | 18 +
monitor/qmp.c | 11 +
monitor/stubs.c | 9 +
qemu-options.hx | 76 +++
22 files changed, 1455 insertions(+), 8 deletions(-)
create mode 100644 accel/kvm/vmi.c
create mode 100644 accel/stubs/vmi-stubs.c
create mode 100644 include/sysemu/vmi-handshake.h
create mode 100644 include/sysemu/vmi-intercept.h
create mode 100644 monitor/stubs.c
base-commit: 14e5526b51910efd62cd31cd95b49baca975c83f
CC: Stefan Hajnoczi <stefa...@redhat.com>
CC: Paolo Bonzini <pbonz...@redhat.com>
CC: Tamas K Lengyel <ta...@tklengyel.com>
CC: Mathieu Tarral <mathieu.tar...@protonmail.com>
CC: Samuel Laurén <samuel.lau...@iki.fi>
CC: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
CC: Patrick Colp <patrick.c...@oracle.com>
CC: Jan Kiszka <jan.kis...@siemens.com>
CC: "Marc-André Lureau" <marcandre.lur...@redhat.com>
CC: Richard Henderson <r...@twiddle.net>
CC: Eduardo Habkost <ehabk...@redhat.com>
CC: "Michael S. Tsirkin" <m...@redhat.com>
CC: Marcel Apfelbaum <marcel.apfelb...@gmail.com>
CC: Markus Armbruster <arm...@redhat.com>
CC: Juan Quintela <quint...@redhat.com>
CC: "Dr. David Alan Gilbert" <dgilb...@redhat.com>
CC: Marian Rotariu <marian.c.rota...@gmail.com>
CC: Mihai Donțu <mdo...@bitdefender.com>
