i386/sev: Introduce 'sev-snp-guest' object

SEV-SNP support relies on a different set of properties/state than the
existing 'sev-guest' object. This patch introduces the 'sev-snp-guest'
object, which can be used to configure an SEV-SNP guest. For example,
a default-configured SEV-SNP guest with no additional information
passed in for use with attestation:

  -object sev-snp-guest,id=sev0

or a fully-specified SEV-SNP guest where all spec-defined binary
blobs are passed in as base64-encoded strings:

  -object sev-snp-guest,id=sev0, \
    policy=0x30000, \
    init-flags=0, \
    id-block=YWFhYWFhYWFhYWFhYWFhCg==, \
    id-auth=CxHK/OKLkXGn/KpAC7Wl1FSiisWDbGTEKz..., \
    author-key-enabled=on, \
    host-data=LNkCWBRC5CcdGXirbNUV1OrsR28s..., \
    guest-visible-workarounds=AA==, \

See the QAPI schema updates included in this patch for more usage
details.

In some cases these blobs may be up to 4096 characters, but this is
generally well below the default limit for linux hosts where
command-line sizes are defined by the sysconf-configurable ARG_MAX
value, which defaults to 2097152 characters for Ubuntu hosts, for
example.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Co-developed-by: Michael Roth <michael.roth@amd.com>
Acked-by: Markus Armbruster <armbru@redhat.com> (for QAPI schema)
Signed-off-by: Michael Roth <michael.roth@amd.com>
Co-developed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Signed-off-by: Pankaj Gupta <pankaj.gupta@amd.com>
Message-ID: <20240530111643.1091816-8-pankaj.gupta@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 58 insertions, 0 deletions

diff --git a/qapi/qom.json b/qapi/qom.json
index 056b38f..8bd2992 100644
--- a/qapi/qom.json
+++ b/qapi/qom.json
@@ -930,6 +930,62 @@
             '*legacy-vm-type': 'bool' } }
 
 ##
+# @SevSnpGuestProperties:
+#
+# Properties for sev-snp-guest objects.  Most of these are direct
+# arguments for the KVM_SNP_* interfaces documented in the Linux
+# kernel source under
+# Documentation/arch/x86/amd-memory-encryption.rst, which are in turn
+# closely coupled with the SNP_INIT/SNP_LAUNCH_* firmware commands
+# documented in the SEV-SNP Firmware ABI Specification (Rev 0.9).
+#
+# More usage information is also available in the QEMU source tree
+# under docs/amd-memory-encryption.
+#
+# @policy: the 'POLICY' parameter to the SNP_LAUNCH_START command, as
+#     defined in the SEV-SNP firmware ABI (default: 0x30000)
+#
+# @guest-visible-workarounds: 16-byte, base64-encoded blob to report
+#     hypervisor-defined workarounds, corresponding to the 'GOSVW'
+#     parameter of the SNP_LAUNCH_START command defined in the SEV-SNP
+#     firmware ABI (default: all-zero)
+#
+# @id-block: 96-byte, base64-encoded blob to provide the 'ID Block'
+#     structure for the SNP_LAUNCH_FINISH command defined in the
+#     SEV-SNP firmware ABI (default: all-zero)
+#
+# @id-auth: 4096-byte, base64-encoded blob to provide the 'ID
+#     Authentication Information Structure' for the SNP_LAUNCH_FINISH
+#     command defined in the SEV-SNP firmware ABI (default: all-zero)
+#
+# @author-key-enabled: true if 'id-auth' blob contains the 'AUTHOR_KEY'
+#     field defined SEV-SNP firmware ABI (default: false)
+#
+# @host-data: 32-byte, base64-encoded, user-defined blob to provide to
+#     the guest, as documented for the 'HOST_DATA' parameter of the
+#     SNP_LAUNCH_FINISH command in the SEV-SNP firmware ABI (default:
+#     all-zero)
+#
+# @vcek-disabled: Guests are by default allowed to choose between VLEK
+#     (Versioned Loaded Endorsement Key) or VCEK (Versioned Chip
+#     Endorsement Key) when requesting attestation reports from
+#     firmware. Set this to true to disable the use of VCEK.
+#     (default: false) (since: 9.1)
+#
+# Since: 9.1
+##
+{ 'struct': 'SevSnpGuestProperties',
+  'base': 'SevCommonProperties',
+  'data': {
+            '*policy': 'uint64',
+            '*guest-visible-workarounds': 'str',
+            '*id-block': 'str',
+            '*id-auth': 'str',
+            '*author-key-enabled': 'bool',
+            '*host-data': 'str',
+            '*vcek-disabled': 'bool' } }
+
+##
 # @ThreadContextProperties:
 #
 # Properties for thread context objects.
@@ -1007,6 +1063,7 @@
     { 'name': 'secret_keyring',
       'if': 'CONFIG_SECRET_KEYRING' },
     'sev-guest',
+    'sev-snp-guest',
     'thread-context',
     's390-pv-guest',
     'throttle-group',
@@ -1077,6 +1134,7 @@
       'secret_keyring':             { 'type': 'SecretKeyringProperties',
                                       'if': 'CONFIG_SECRET_KEYRING' },
       'sev-guest':                  'SevGuestProperties',
+      'sev-snp-guest':              'SevSnpGuestProperties',
       'thread-context':             'ThreadContextProperties',
       'throttle-group':             'ThrottleGroupProperties',
       'tls-creds-anon':             'TlsCredsAnonProperties',