cachepc-qemu

Fork of AMDESE/qemu with changes for cachepc side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-qemu
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qemu-pr-helper.rst (2575B)

      1==================================
      2QEMU persistent reservation helper
      3==================================
      4
      5Synopsis
      6--------
      7
      8**qemu-pr-helper** [*OPTION*]
      9
     10Description
     11-----------
     12
     13Implements the persistent reservation helper for QEMU.
     14
     15SCSI persistent reservations allow restricting access to block devices
     16to specific initiators in a shared storage setup.  When implementing
     17clustering of virtual machines, it is a common requirement for virtual
     18machines to send persistent reservation SCSI commands.  However,
     19the operating system restricts sending these commands to unprivileged
     20programs because incorrect usage can disrupt regular operation of the
     21storage fabric. QEMU's SCSI passthrough devices ``scsi-block``
     22and ``scsi-generic`` support passing guest persistent reservation
     23requests to a privileged external helper program. :program:`qemu-pr-helper`
     24is that external helper; it creates a socket which QEMU can
     25connect to to communicate with it.
     26
     27If you want to run VMs in a setup like this, this helper should be
     28started as a system service, and you should read the QEMU manual
     29section on "persistent reservation managers" to find out how to
     30configure QEMU to connect to the socket created by
     31:program:`qemu-pr-helper`.
     32
     33After connecting to the socket, :program:`qemu-pr-helper` can
     34optionally drop root privileges, except for those capabilities that
     35are needed for its operation.
     36
     37:program:`qemu-pr-helper` can also use the systemd socket activation
     38protocol.  In this case, the systemd socket unit should specify a
     39Unix stream socket, like this::
     40
     41    [Socket]
     42    ListenStream=/var/run/qemu-pr-helper.sock
     43
     44Options
     45-------
     46
     47.. program:: qemu-pr-helper
     48
     49.. option:: -d, --daemon
     50
     51  run in the background (and create a PID file)
     52
     53.. option:: -q, --quiet
     54
     55  decrease verbosity
     56
     57.. option:: -v, --verbose
     58
     59  increase verbosity
     60
     61.. option:: -f, --pidfile=PATH
     62
     63  PID file when running as a daemon. By default the PID file
     64  is created in the system runtime state directory, for example
     65  :file:`/var/run/qemu-pr-helper.pid`.
     66
     67.. option:: -k, --socket=PATH
     68
     69  path to the socket. By default the socket is created in
     70  the system runtime state directory, for example
     71  :file:`/var/run/qemu-pr-helper.sock`.
     72
     73.. option:: -T, --trace [[enable=]PATTERN][,events=FILE][,file=FILE]
     74
     75  .. include:: ../qemu-option-trace.rst.inc
     76
     77.. option:: -u, --user=USER
     78
     79  user to drop privileges to
     80
     81.. option:: -g, --group=GROUP
     82
     83  group to drop privileges to
     84
     85.. option:: -h, --help
     86
     87  Display a help message and exit.
     88
     89.. option:: -V, --version
     90
     91  Display version information and exit.