[RFC PATCH v2 12/12] i386/sev: update query-sev QAPI format to handle SEV-SNP

[Michael Roth <michael.roth@amd.com>]

Most of the current 'query-sev' command is relevant to both legacy
SEV/SEV-ES guests and SEV-SNP guests, with 2 exceptions:

  - 'policy' is a 64-bit field for SEV-SNP, not 32-bit, and
    the meaning of the bit positions has changed
  - 'handle' is not relevant to SEV-SNP

To address this, this patch adds a new 'sev-type' field that can be
used as a discriminator to select between SEV and SEV-SNP-specific
fields/formats without breaking compatibility for existing management
tools (so long as management tools that add support for launching
SEV-SNP guest update their handling of query-sev appropriately).

The corresponding HMP command has also been fixed up similarly.

Signed-off-by: Michael Roth <michael.roth@amd.com>
---
 qapi/misc-target.json  | 71 +++++++++++++++++++++++++++++++++---------
 target/i386/monitor.c  | 29 +++++++++++++----
 target/i386/sev.c      | 22 +++++++------
 target/i386/sev_i386.h |  3 ++
 4 files changed, 95 insertions(+), 30 deletions(-)

diff --git a/qapi/misc-target.json b/qapi/misc-target.json
index 3b05ad3dbf..80f994ff9b 100644
--- a/qapi/misc-target.json
+++ b/qapi/misc-target.json
@@ -81,6 +81,49 @@
            'send-update', 'receive-update' ],
   'if': 'TARGET_I386' }
 
+##
+# @SevGuestType:
+#
+# An enumeration indicating the type of SEV guest being run.
+#
+# @sev:     The guest is a legacy SEV or SEV-ES guest.
+# @sev-snp: The guest is an SEV-SNP guest.
+#
+# Since: 6.2
+##
+{ 'enum': 'SevGuestType',
+  'data': [ 'sev', 'sev-snp' ],
+  'if': 'TARGET_I386' }
+
+##
+# @SevGuestInfo:
+#
+# Information specific to legacy SEV/SEV-ES guests.
+#
+# @policy: SEV policy value
+#
+# @handle: SEV firmware handle
+#
+# Since: 2.12
+##
+{ 'struct': 'SevGuestInfo',
+  'data': { 'policy': 'uint32',
+            'handle': 'uint32' },
+  'if': 'TARGET_I386' }
+
+##
+# @SevSnpGuestInfo:
+#
+# Information specific to SEV-SNP guests.
+#
+# @policy: SEV-SNP policy value
+#
+# Since: 6.2
+##
+{ 'struct': 'SevSnpGuestInfo',
+  'data': { 'policy': 'uint64' },
+  'if': 'TARGET_I386' }
+
 ##
 # @SevInfo:
 #
@@ -94,25 +137,25 @@
 #
 # @build-id: SEV FW build id
 #
-# @policy: SEV policy value
-#
 # @state: SEV guest state
 #
-# @handle: SEV firmware handle
+# @sev-type: Type of SEV guest being run
 #
 # Since: 2.12
 ##
-{ 'struct': 'SevInfo',
-    'data': { 'enabled': 'bool',
-              'api-major': 'uint8',
-              'api-minor' : 'uint8',
-              'build-id' : 'uint8',
-              'policy' : 'uint32',
-              'state' : 'SevState',
-              'handle' : 'uint32'
-            },
-  'if': 'TARGET_I386'
-}
+{ 'union': 'SevInfo',
+  'base': { 'enabled': 'bool',
+            'api-major': 'uint8',
+            'api-minor' : 'uint8',
+            'build-id' : 'uint8',
+            'state' : 'SevState',
+            'sev-type' : 'SevGuestType' },
+  'discriminator': 'sev-type',
+  'data': {
+      'sev': 'SevGuestInfo',
+      'sev-snp': 'SevSnpGuestInfo' },
+  'if': 'TARGET_I386' }
+
 
 ##
 # @query-sev:
diff --git a/target/i386/monitor.c b/target/i386/monitor.c
index 119211f0b0..85a8bc2bef 100644
--- a/target/i386/monitor.c
+++ b/target/i386/monitor.c
@@ -692,20 +692,37 @@ void hmp_info_sev(Monitor *mon, const QDict *qdict)
 {
     SevInfo *info = sev_get_info();
 
-    if (info && info->enabled) {
-        monitor_printf(mon, "handle: %d\n", info->handle);
+    if (!info || !info->enabled) {
+        monitor_printf(mon, "SEV is not enabled\n");
+        goto out;
+    }
+
+    if (sev_snp_enabled()) {
         monitor_printf(mon, "state: %s\n", SevState_str(info->state));
         monitor_printf(mon, "build: %d\n", info->build_id);
         monitor_printf(mon, "api version: %d.%d\n",
                        info->api_major, info->api_minor);
         monitor_printf(mon, "debug: %s\n",
-                       info->policy & SEV_POLICY_NODBG ? "off" : "on");
-        monitor_printf(mon, "key-sharing: %s\n",
-                       info->policy & SEV_POLICY_NOKS ? "off" : "on");
+                       info->u.sev_snp.policy & SEV_SNP_POLICY_DBG ? "on"
+                                                                   : "off");
+        monitor_printf(mon, "SMT allowed: %s\n",
+                       info->u.sev_snp.policy & SEV_SNP_POLICY_SMT ? "on"
+                                                                   : "off");
+        monitor_printf(mon, "SEV type: %s\n", SevGuestType_str(info->sev_type));
     } else {
-        monitor_printf(mon, "SEV is not enabled\n");
+        monitor_printf(mon, "handle: %d\n", info->u.sev.handle);
+        monitor_printf(mon, "state: %s\n", SevState_str(info->state));
+        monitor_printf(mon, "build: %d\n", info->build_id);
+        monitor_printf(mon, "api version: %d.%d\n",
+                       info->api_major, info->api_minor);
+        monitor_printf(mon, "debug: %s\n",
+                       info->u.sev.policy & SEV_POLICY_NODBG ? "off" : "on");
+        monitor_printf(mon, "key-sharing: %s\n",
+                       info->u.sev.policy & SEV_POLICY_NOKS ? "off" : "on");
+        monitor_printf(mon, "SEV type: %s\n", SevGuestType_str(info->sev_type));
     }
 
+out:
     qapi_free_SevInfo(info);
 }
 
diff --git a/target/i386/sev.c b/target/i386/sev.c
index 72a6146295..fac2755e68 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -704,25 +704,27 @@ sev_get_info(void)
 {
     SevInfo *info;
     SevCommonState *sev_common = SEV_COMMON(MACHINE(qdev_get_machine())->cgs);
-    SevGuestState *sev_guest =
-        (SevGuestState *)object_dynamic_cast(OBJECT(sev_common),
-                                             TYPE_SEV_GUEST);
 
     info = g_new0(SevInfo, 1);
     info->enabled = sev_enabled();
 
     if (info->enabled) {
-        if (sev_guest) {
-            info->handle = sev_guest->handle;
-        }
         info->api_major = sev_common->api_major;
         info->api_minor = sev_common->api_minor;
         info->build_id = sev_common->build_id;
         info->state = sev_common->state;
-        /* we only report the lower 32-bits of policy for SNP, ok for now... */
-        info->policy =
-            (uint32_t)object_property_get_uint(OBJECT(sev_common),
-                                               "policy", NULL);
+
+        if (sev_snp_enabled()) {
+            info->sev_type = SEV_GUEST_TYPE_SEV_SNP;
+            info->u.sev_snp.policy =
+                object_property_get_uint(OBJECT(sev_common), "policy", NULL);
+        } else {
+            info->sev_type = SEV_GUEST_TYPE_SEV;
+            info->u.sev.handle = SEV_GUEST(sev_common)->handle;
+            info->u.sev.policy =
+                (uint32_t)object_property_get_uint(OBJECT(sev_common),
+                                                   "policy", NULL);
+        }
     }
 
     return info;
diff --git a/target/i386/sev_i386.h b/target/i386/sev_i386.h
index e0e1a599be..948d8f1079 100644
--- a/target/i386/sev_i386.h
+++ b/target/i386/sev_i386.h
@@ -28,6 +28,9 @@
 #define SEV_POLICY_DOMAIN       0x10
 #define SEV_POLICY_SEV          0x20
 
+#define SEV_SNP_POLICY_SMT      0x10000
+#define SEV_SNP_POLICY_DBG      0x80000
+
 extern bool sev_es_enabled(void);
 extern bool sev_snp_enabled(void);
 extern uint64_t sev_get_me_mask(void);
-- 
2.25.1