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45 lines
1.7 KiB
ReStructuredText
Confidential Guest Support
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==========================
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Traditionally, hypervisors such as QEMU have complete access to a
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guest's memory and other state, meaning that a compromised hypervisor
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can compromise any of its guests. A number of platforms have added
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mechanisms in hardware and/or firmware which give guests at least some
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protection from a compromised hypervisor. This is obviously
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especially desirable for public cloud environments.
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These mechanisms have different names and different modes of
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operation, but are often referred to as Secure Guests or Confidential
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Guests. We use the term "Confidential Guest Support" to distinguish
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this from other aspects of guest security (such as security against
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attacks from other guests, or from network sources).
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Running a Confidential Guest
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----------------------------
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To run a confidential guest you need to add two command line parameters:
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1. Use ``-object`` to create a "confidential guest support" object. The
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type and parameters will vary with the specific mechanism to be
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used
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2. Set the ``confidential-guest-support`` machine parameter to the ID of
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the object from (1).
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Example (for AMD SEV)::
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qemu-system-x86_64 \
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<other parameters> \
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-machine ...,confidential-guest-support=sev0 \
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-object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=1
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Supported mechanisms
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--------------------
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Currently supported confidential guest mechanisms are:
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* AMD Secure Encrypted Virtualization (SEV) (see :doc:`i386/amd-memory-encryption`)
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* POWER Protected Execution Facility (PEF) (see :ref:`power-papr-protected-execution-facility-pef`)
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* s390x Protected Virtualization (PV) (see :doc:`s390x/protvirt`)
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Other mechanisms may be supported in future.
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