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Documentation: kvm/sev: separate description of firmware
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The description of firmware is included part under the "SEV Key Management"
header, part under the KVM_SEV_INIT ioctl.  Put these two bits together and
and rename "SEV Key Management" to what it actually is, namely a description
of the KVM_MEMORY_ENCRYPT_OP API.

Reviewed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Paolo Bonzini committed Mar 18, 2024
1 parent f3c8006 commit 19cebba
Showing 1 changed file with 17 additions and 12 deletions.
29 changes: 17 additions & 12 deletions Documentation/virt/kvm/x86/amd-memory-encryption.rst
Original file line number Diff line number Diff line change
Expand Up @@ -46,14 +46,8 @@ SEV hardware uses ASIDs to associate a memory encryption key with a VM.
Hence, the ASID for the SEV-enabled guests must be from 1 to a maximum value
defined in the CPUID 0x8000001f[ecx] field.

SEV Key Management
==================

The SEV guest key management is handled by a separate processor called the AMD
Secure Processor (AMD-SP). Firmware running inside the AMD-SP provides a secure
key management interface to perform common hypervisor activities such as
encrypting bootstrap code, snapshot, migrating and debugging the guest. For more
information, see the SEV Key Management spec [api-spec]_
The KVM_MEMORY_ENCRYPT_OP ioctl
===============================

The main ioctl to access SEV is KVM_MEMORY_ENCRYPT_OP. If the argument
to KVM_MEMORY_ENCRYPT_OP is NULL, the ioctl returns 0 if SEV is enabled
Expand Down Expand Up @@ -87,10 +81,6 @@ guests, such as launching, running, snapshotting, migrating and decommissioning.
The KVM_SEV_INIT command is used by the hypervisor to initialize the SEV platform
context. In a typical workflow, this command should be the first command issued.

The firmware can be initialized either by using its own non-volatile storage or
the OS can manage the NV storage for the firmware using the module parameter
``init_ex_path``. If the file specified by ``init_ex_path`` does not exist or
is invalid, the OS will create or override the file with output from PSP.

Returns: 0 on success, -negative on error

Expand Down Expand Up @@ -434,6 +424,21 @@ issued by the hypervisor to make the guest ready for execution.

Returns: 0 on success, -negative on error

Firmware Management
===================

The SEV guest key management is handled by a separate processor called the AMD
Secure Processor (AMD-SP). Firmware running inside the AMD-SP provides a secure
key management interface to perform common hypervisor activities such as
encrypting bootstrap code, snapshot, migrating and debugging the guest. For more
information, see the SEV Key Management spec [api-spec]_

The AMD-SP firmware can be initialized either by using its own non-volatile
storage or the OS can manage the NV storage for the firmware using
parameter ``init_ex_path`` of the ``ccp`` module. If the file specified
by ``init_ex_path`` does not exist or is invalid, the OS will create or
override the file with PSP non-volatile storage.

References
==========

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