igvm: add support for igvm memory map parameter in native mode

Add and wire up qigvm_x86_get_mem_map_entry function which converts the
e820 table into an igvm memory map parameter.  This makes igvm files for
the native (non-confidential) platform with memory map parameter work.

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Luigi Leonardi <leonardi@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-ID: <20251029105555.2492276-4-kraxel@redhat.com>

backends/igvm.c

@@ -12,6 +12,7 @@
 #include "qemu/osdep.h"
 
 #include "qapi/error.h"
+#include "qemu/target-info-qapi.h"
 #include "system/igvm.h"
 #include "system/memory.h"
 #include "system/address-spaces.h"
@@ -543,6 +544,8 @@ static int qigvm_directive_memory_map(QIgvm *ctx, const uint8_t *header_data,
                                       Error **errp)
 {
     const IGVM_VHS_PARAMETER *param = (const IGVM_VHS_PARAMETER *)header_data;
+    int (*get_mem_map_entry)(int index, ConfidentialGuestMemoryMapEntry *entry,
+                             Error **errp) = NULL;
     QIgvmParameterData *param_entry;
     int max_entry_count;
     int entry = 0;
@@ -550,7 +553,13 @@ static int qigvm_directive_memory_map(QIgvm *ctx, const uint8_t *header_data,
     ConfidentialGuestMemoryMapEntry cgmm_entry;
     int retval = 0;
 
-    if (!ctx->cgs) {
+    if (ctx->cgs && ctx->cgsc->get_mem_map_entry) {
+        get_mem_map_entry = ctx->cgsc->get_mem_map_entry;
+
+    } else if (target_arch() == SYS_EMU_TARGET_X86_64) {
+        get_mem_map_entry = qigvm_x86_get_mem_map_entry;
+
+    } else {
         error_setg(errp,
                    "IGVM file contains a memory map but this is not supported "
                    "by the current system.");
@@ -565,7 +574,7 @@ static int qigvm_directive_memory_map(QIgvm *ctx, const uint8_t *header_data,
                 param_entry->size / sizeof(IGVM_VHS_MEMORY_MAP_ENTRY);
             mm_entry = (IGVM_VHS_MEMORY_MAP_ENTRY *)param_entry->data;
 
-            retval = ctx->cgsc->get_mem_map_entry(entry, &cgmm_entry, errp);
+            retval = get_mem_map_entry(entry, &cgmm_entry, errp);
             while (retval == 0) {
                 if (entry >= max_entry_count) {
                     error_setg(
@@ -598,8 +607,7 @@ static int qigvm_directive_memory_map(QIgvm *ctx, const uint8_t *header_data,
                         IGVM_MEMORY_MAP_ENTRY_TYPE_PLATFORM_RESERVED;
                     break;
                 }
-                retval =
-                    ctx->cgsc->get_mem_map_entry(++entry, &cgmm_entry, errp);
+                retval = get_mem_map_entry(++entry, &cgmm_entry, errp);
             }
             if (retval < 0) {
                 return retval;

include/system/igvm.h

@@ -19,4 +19,9 @@
 int qigvm_process_file(IgvmCfg *igvm, ConfidentialGuestSupport *cgs,
                       bool onlyVpContext, Error **errp);
 
+/* x86 native */
+int qigvm_x86_get_mem_map_entry(int index,
+                                ConfidentialGuestMemoryMapEntry *entry,
+                                Error **errp);
+
 #endif

stubs/igvm.c

@@ -0,0 +1,21 @@
+/*
+ * QEMU IGVM, stubs
+ *
+ * Copyright (C) 2026 Red Hat
+ *
+ * Authors:
+ *  Gerd Hoffmann <kraxel@redhat.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+
+#include "system/igvm.h"
+
+int qigvm_x86_get_mem_map_entry(int index,
+                                ConfidentialGuestMemoryMapEntry *entry,
+                                Error **errp)
+{
+    return -1;
+}

stubs/meson.build

@@ -74,6 +74,7 @@ if have_system
   stub_ss.add(files('dump.c'))
   stub_ss.add(files('cmos.c'))
   stub_ss.add(files('fw_cfg.c'))
+  stub_ss.add(files('igvm.c'))
   stub_ss.add(files('target-get-monitor-def.c'))
   stub_ss.add(files('target-monitor-defs.c'))
   stub_ss.add(files('win32-kbd-hook.c'))

target/i386/igvm.c

@@ -0,0 +1,46 @@
+/*
+ * QEMU IGVM, support for native x86 guests
+ *
+ * Copyright (C) 2026 Red Hat
+ *
+ * Authors:
+ *  Gerd Hoffmann <kraxel@redhat.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+
+#include "hw/i386/e820_memory_layout.h"
+#include "system/igvm.h"
+
+/*
+ * convert e820 table into igvm memory map
+ */
+int qigvm_x86_get_mem_map_entry(int index,
+                                ConfidentialGuestMemoryMapEntry *entry,
+                                Error **errp)
+{
+    struct e820_entry *table;
+    int num_entries;
+
+    num_entries = e820_get_table(&table);
+    if ((index < 0) || (index >= num_entries)) {
+        return 1;
+    }
+    entry->gpa = table[index].address;
+    entry->size = table[index].length;
+    switch (table[index].type) {
+    case E820_RAM:
+        entry->type = CGS_MEM_RAM;
+        break;
+    case E820_RESERVED:
+        entry->type = CGS_MEM_RESERVED;
+        break;
+    default:
+        /* should not happen */
+        error_setg(errp, "unknown e820 type");
+        return -1;
+    }
+    return 0;
+}

target/i386/meson.build

@@ -26,6 +26,9 @@ i386_system_ss.add(files(
 ))
 i386_system_ss.add(when: 'CONFIG_SEV', if_true: files('sev.c'),
                                        if_false: files('sev-system-stub.c'))
+if igvm.found()
+  i386_system_ss.add(files('igvm.c'))
+endif
 
 i386_user_ss = ss.source_set()