1Confidential Guest Support
2==========================
3
4Traditionally, hypervisors such as QEMU have complete access to a
5guest's memory and other state, meaning that a compromised hypervisor
6can compromise any of its guests.  A number of platforms have added
7mechanisms in hardware and/or firmware which give guests at least some
8protection from a compromised hypervisor.  This is obviously
9especially desirable for public cloud environments.
10
11These mechanisms have different names and different modes of
12operation, but are often referred to as Secure Guests or Confidential
13Guests.  We use the term "Confidential Guest Support" to distinguish
14this from other aspects of guest security (such as security against
15attacks from other guests, or from network sources).
16
17Running a Confidential Guest
18----------------------------
19
20To run a confidential guest you need to add two command line parameters:
21
221. Use ``-object`` to create a "confidential guest support" object.  The
23   type and parameters will vary with the specific mechanism to be
24   used
252. Set the ``confidential-guest-support`` machine parameter to the ID of
26   the object from (1).
27
28Example (for AMD SEV)::
29
30    qemu-system-x86_64 \
31        <other parameters> \
32        -machine ...,confidential-guest-support=sev0 \
33        -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=1
34
35Supported mechanisms
36--------------------
37
38Currently supported confidential guest mechanisms are:
39
40* AMD Secure Encrypted Virtualization (SEV) (see :doc:`i386/amd-memory-encryption`)
41* POWER Protected Execution Facility (PEF) (see :ref:`power-papr-protected-execution-facility-pef`)
42* s390x Protected Virtualization (PV) (see :doc:`s390x/protvirt`)
43
44Other mechanisms may be supported in future.
45