backends/igvm: Add IGVM loader and configuration

Adds an IGVM loader to QEMU which processes a given IGVM file and
applies the directives within the file to the current guest
configuration.

The IGVM loader can be used to configure both confidential and
non-confidential guests. For confidential guests, the
ConfidentialGuestSupport object for the system is used to encrypt
memory, apply the initial CPU state and perform other confidential guest
operations.

The loader is configured via a new IgvmCfg QOM object which allows the
user to provide a path to the IGVM file to process.

Signed-off-by: Roy Hopkins <roy.hopkins@randomman.co.uk>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Gerd Hoffman <kraxel@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/ae3a07d8f514d93845a9c16bb155c847cb567b0d.1751554099.git.roy.hopkins@randomman.co.uk
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

backends/igvm-cfg.c

@@ -0,0 +1,51 @@
+/*
+ * QEMU IGVM interface
+ *
+ * Copyright (C) 2023-2024 SUSE
+ *
+ * Authors:
+ *  Roy Hopkins <roy.hopkins@randomman.co.uk>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+
+#include "system/igvm-cfg.h"
+#include "igvm.h"
+#include "qom/object_interfaces.h"
+
+static char *get_igvm(Object *obj, Error **errp)
+{
+    IgvmCfg *igvm = IGVM_CFG(obj);
+    return g_strdup(igvm->filename);
+}
+
+static void set_igvm(Object *obj, const char *value, Error **errp)
+{
+    IgvmCfg *igvm = IGVM_CFG(obj);
+    g_free(igvm->filename);
+    igvm->filename = g_strdup(value);
+}
+
+OBJECT_DEFINE_TYPE_WITH_INTERFACES(IgvmCfg, igvm_cfg, IGVM_CFG, OBJECT,
+                                   { TYPE_USER_CREATABLE }, { NULL })
+
+static void igvm_cfg_class_init(ObjectClass *oc, const void *data)
+{
+    IgvmCfgClass *igvmc = IGVM_CFG_CLASS(oc);
+
+    object_class_property_add_str(oc, "file", get_igvm, set_igvm);
+    object_class_property_set_description(oc, "file",
+                                          "Set the IGVM filename to use");
+
+    igvmc->process = qigvm_process_file;
+}
+
+static void igvm_cfg_init(Object *obj)
+{
+}
+
+static void igvm_cfg_finalize(Object *obj)
+{
+}

backends/igvm.h

@@ -0,0 +1,22 @@
+/*
+ * QEMU IGVM configuration backend for Confidential Guests
+ *
+ * Copyright (C) 2023-2024 SUSE
+ *
+ * Authors:
+ *  Roy Hopkins <roy.hopkins@randomman.co.uk>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef BACKENDS_IGVM_H
+#define BACKENDS_IGVM_H
+
+#include "system/confidential-guest-support.h"
+#include "system/igvm-cfg.h"
+#include "qapi/error.h"
+
+int qigvm_process_file(IgvmCfg *igvm, ConfidentialGuestSupport *cgs,
+                      Error **errp);
+
+#endif

backends/meson.build

@@ -36,6 +36,8 @@ system_ss.add(when: gio, if_true: files('dbus-vmstate.c'))
 system_ss.add(when: 'CONFIG_SGX', if_true: files('hostmem-epc.c'))
 if igvm.found()
   system_ss.add(igvm)
+  system_ss.add(files('igvm-cfg.c'), igvm)
+  system_ss.add(files('igvm.c'), igvm)
 endif
 
 system_ss.add(when: 'CONFIG_SPDM_SOCKET', if_true: files('spdm-socket.c'))

include/system/igvm-cfg.h

@@ -0,0 +1,46 @@
+/*
+ * QEMU IGVM interface
+ *
+ * Copyright (C) 2024 SUSE
+ *
+ * Authors:
+ *  Roy Hopkins <roy.hopkins@randomman.co.uk>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef QEMU_IGVM_CFG_H
+#define QEMU_IGVM_CFG_H
+
+#include "qom/object.h"
+
+typedef struct IgvmCfg {
+    ObjectClass parent_class;
+
+    /*
+     * filename: Filename that specifies a file that contains the configuration
+     *           of the guest in Independent Guest Virtual Machine (IGVM)
+     *           format.
+     */
+    char *filename;
+} IgvmCfg;
+
+typedef struct IgvmCfgClass {
+    ObjectClass parent_class;
+
+    /*
+     * If an IGVM filename has been specified then process the IGVM file.
+     * Performs a no-op if no filename has been specified.
+     *
+     * Returns 0 for ok and -1 on error.
+     */
+    int (*process)(IgvmCfg *cfg, ConfidentialGuestSupport *cgs,
+                   Error **errp);
+
+} IgvmCfgClass;
+
+#define TYPE_IGVM_CFG "igvm-cfg"
+
+OBJECT_DECLARE_TYPE(IgvmCfg, IgvmCfgClass, IGVM_CFG)
+
+#endif

qapi/qom.json

@@ -932,6 +932,19 @@
   'data': { '*filename': 'str' },
   'if': 'CONFIG_POSIX' }
 
+##
+# @IgvmCfgProperties:
+#
+# Properties common to objects that handle IGVM files.
+#
+# @file: IGVM file to use to configure guest
+#
+# Since: 10.1
+##
+{ 'struct': 'IgvmCfgProperties',
+  'if': 'CONFIG_IGVM',
+  'data': { 'file': 'str' } }
+
 ##
 # @SevCommonProperties:
 #
@@ -1142,6 +1155,8 @@
     'filter-redirector',
     'filter-replay',
     'filter-rewriter',
+    { 'name': 'igvm-cfg',
+      'if': 'CONFIG_IGVM' },
     'input-barrier',
     { 'name': 'input-linux',
       'if': 'CONFIG_LINUX' },
@@ -1218,6 +1233,8 @@
       'filter-redirector':          'FilterRedirectorProperties',
       'filter-replay':              'NetfilterProperties',
       'filter-rewriter':            'FilterRewriterProperties',
+      'igvm-cfg':                   { 'type': 'IgvmCfgProperties',
+                                      'if': 'CONFIG_IGVM' },
       'input-barrier':              'InputBarrierProperties',
       'input-linux':                { 'type': 'InputLinuxProperties',
                                       'if': 'CONFIG_LINUX' },