hw/i386: Add igvm-cfg object and processing for IGVM files

An IGVM file contains configuration of guest state that should be
applied during configuration of the guest, before the guest is started.

This patch allows the user to add an igvm-cfg object to an X86 machine
configuration that allows an IGVM file to be configured that will be
applied to the guest before it is started.

If an IGVM configuration is provided then the IGVM file is processed at
the end of the board initialization, before the state transition to
PHASE_MACHINE_INITIALIZED.

Signed-off-by: Roy Hopkins <roy.hopkins@randomman.co.uk>
Acked-by: Gerd Hoffman <kraxel@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Ani Sinha <anisinha@redhat.com>
Link: https://lore.kernel.org/r/23bc66ae4504ba5cf2134826e055b25df3fc9cd9.1751554099.git.roy.hopkins@randomman.co.uk
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/i386/pc.c

@@ -1833,6 +1833,18 @@ static void pc_machine_class_init(ObjectClass *oc, const void *data)
     object_class_property_add_bool(oc, "fd-bootchk",
         pc_machine_get_fd_bootchk,
         pc_machine_set_fd_bootchk);
+
+#if defined(CONFIG_IGVM)
+    object_class_property_add_link(oc, "igvm-cfg",
+                                   TYPE_IGVM_CFG,
+                                   offsetof(X86MachineState, igvm),
+                                   object_property_allow_set_link,
+                                   OBJ_PROP_LINK_STRONG);
+    object_class_property_set_description(oc, "igvm-cfg",
+                                          "Set IGVM configuration");
+#endif
+
+
 }
 
 static const TypeInfo pc_machine_info = {

hw/i386/pc_piix.c

@@ -366,6 +366,16 @@ static void pc_init1(MachineState *machine, const char *pci_type)
                                x86_nvdimm_acpi_dsmio,
                                x86ms->fw_cfg, OBJECT(pcms));
     }
+
+#if defined(CONFIG_IGVM)
+    /* Apply guest state from IGVM if supplied */
+    if (x86ms->igvm) {
+        if (IGVM_CFG_GET_CLASS(x86ms->igvm)
+                ->process(x86ms->igvm, machine->cgs, &error_fatal) < 0) {
+            g_assert_not_reached();
+        }
+    }
+#endif
 }
 
 typedef enum PCSouthBridgeOption {

hw/i386/pc_q35.c

@@ -325,6 +325,16 @@ static void pc_q35_init(MachineState *machine)
                                x86_nvdimm_acpi_dsmio,
                                x86ms->fw_cfg, OBJECT(pcms));
     }
+
+#if defined(CONFIG_IGVM)
+    /* Apply guest state from IGVM if supplied */
+    if (x86ms->igvm) {
+        if (IGVM_CFG_GET_CLASS(x86ms->igvm)
+                ->process(x86ms->igvm, machine->cgs, &error_fatal) < 0) {
+            g_assert_not_reached();
+        }
+    }
+#endif
 }
 
 #define DEFINE_Q35_MACHINE(major, minor) \

include/hw/i386/x86.h

@@ -25,6 +25,7 @@
 #include "hw/intc/ioapic.h"
 #include "hw/isa/isa.h"
 #include "qom/object.h"
+#include "system/igvm-cfg.h"
 
 struct X86MachineClass {
     MachineClass parent;
@@ -92,6 +93,8 @@ struct X86MachineState {
      * which means no limitation on the guest's bus locks.
      */
     uint64_t bus_lock_ratelimit;
+
+    IgvmCfg *igvm;
 };
 
 #define X86_MACHINE_SMM              "smm"

qemu-options.hx

@@ -5992,6 +5992,34 @@ SRST
                  -machine ...,memory-encryption=sev0 \\
                  .....
 
+    ``-object igvm-cfg,file=file``
+        Create an IGVM configuration object that defines the initial state
+        of the guest using a file in that conforms to the Independent Guest
+        Virtual Machine (IGVM) file format.
+
+        This is currently only supported by ``-machine q35`` and
+        ``-machine pc``.
+
+        The ``file`` parameter is used to specify the IGVM file to load.
+        When provided, the IGVM file is used to populate the initial
+        memory of the virtual machine and, depending on the platform, can
+        define the initial processor state, memory map and parameters.
+
+        The IGVM file is expected to contain the firmware for the virtual
+        machine, therefore an ``igvm-cfg`` object cannot be provided along
+        with other ways of specifying firmware, such as the ``-bios``
+        parameter on x86 machines.
+
+        e.g to launch a machine providing the firmware in an IGVM file
+
+        .. parsed-literal::
+
+             # |qemu_system_x86| \\
+                 ...... \\
+                 -object igvm-cfg,id=igvm0,file=bios.igvm \\
+                 -machine ...,igvm-cfg=igvm0 \\
+                 .....
+
     ``-object authz-simple,id=id,identity=string``
         Create an authorization object that will control access to
         network services.