Subject: [PATCH] smbios: CTYPE / SMBIOS_VM_BIT / FIRMWARE

Targets VMAware check: CTYPE / SMBIOS_VM_BIT / FIRMWARE

QEMU keeps synthesising every required SMBIOS structure the domain does not
supply, so identity can be set with -smbios type=N field arguments and real
structures passed with -smbios file= only where they are wanted. What QEMU
fills in by itself must not read as a VM:

  - type 3 chassis type was hard-coded to 1 (Other), which CTYPE flags. It
    defaults to 3 (Desktop) and is set with type=3,chassis-type=N.
  - the type 0 "virtual machine" characteristics bit now defaults off, so a
    type 0 from libvirt <sysinfo>, which cannot pass vm=off, stays clean.
  - unset product and version strings in types 1-4 default to "Unknown"
    instead of the machine description and name ("Standard PC (Q35 + ICH9,
    2009)", "pc-q35-<ver>"), which FIRMWARE matches when it scans SMBIOS on
    Windows.

Applies to QEMU v11.1.2, on top of 04-fw-cfg. Apply from the source root with:
    patch -p1 < 10-smbios.patch

---
diff --git a/hw/i386/fw_cfg.c b/hw/i386/fw_cfg.c
index e5fddbc..bfc193c 100644
--- a/hw/i386/fw_cfg.c
+++ b/hw/i386/fw_cfg.c
@@ -71,13 +71,12 @@ void fw_cfg_build_smbios(PCMachineState *pcms, FWCfgState *fw_cfg,
     unsigned i, array_count;
     MachineState *ms = MACHINE(pcms);
     PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
-    MachineClass *mc = MACHINE_GET_CLASS(pcms);
     X86CPU *cpu = X86_CPU(ms->possible_cpus->cpus[0].cpu);
     int nr_e820;
 
     if (pcmc->smbios_defaults) {
         /* These values are guest ABI, do not change */
-        smbios_set_defaults("Unknown", mc->desc, mc->name);
+        smbios_set_defaults("Unknown", "Unknown", "Unknown");
     }
 
     /* tell smbios about cpuid version and features */
diff --git a/hw/smbios/smbios.c b/hw/smbios/smbios.c
index 7d71418..c557069 100644
--- a/hw/smbios/smbios.c
+++ b/hw/smbios/smbios.c
@@ -62,7 +62,8 @@ static struct {
 
 static struct {
     const char *manufacturer, *version, *serial, *asset, *sku;
-} type3;
+    uint64_t chassis_type;
+} type3 = { .chassis_type = 0x03 }; /* Desktop: QEMU's "Other" reads as a VM */
 
 /*
  * SVVP requires max_speed and current_speed to be set and not being
@@ -282,6 +283,10 @@ static const QemuOptDesc qemu_smbios_type3_opts[] = {
         .name = "sku",
         .type = QEMU_OPT_STRING,
         .help = "SKU number",
+    },{
+        .name = "chassis-type",
+        .type = QEMU_OPT_NUMBER,
+        .help = "chassis type",
     },
     { /* end of list */ }
 };
@@ -656,7 +661,7 @@ static void smbios_build_type_3_table(void)
     SMBIOS_BUILD_TABLE_PRE(3, T3_BASE, true); /* required */
 
     SMBIOS_TABLE_SET_STR(3, manufacturer_str, type3.manufacturer);
-    t->type = 0x01; /* Other */
+    t->type = type3.chassis_type;
     SMBIOS_TABLE_SET_STR(3, version_str, type3.version);
     SMBIOS_TABLE_SET_STR(3, serial_number_str, type3.serial);
     SMBIOS_TABLE_SET_STR(3, asset_tag_number_str, type3.asset);
@@ -1413,7 +1418,7 @@ void smbios_entry_add(QemuOpts *opts, Error **errp)
             save_opt(&smbios_type0.version, opts, "version");
             save_opt(&smbios_type0.date, opts, "date");
             smbios_type0.uefi = qemu_opt_get_bool(opts, "uefi", false);
-            smbios_type0.vm = qemu_opt_get_bool(opts, "vm", true);
+            smbios_type0.vm = qemu_opt_get_bool(opts, "vm", false);
 
             val = qemu_opt_get(opts, "release");
             if (val) {
@@ -1465,6 +1470,12 @@ void smbios_entry_add(QemuOpts *opts, Error **errp)
             save_opt(&type3.serial, opts, "serial");
             save_opt(&type3.asset, opts, "asset");
             save_opt(&type3.sku, opts, "sku");
+            type3.chassis_type = qemu_opt_get_number(opts, "chassis-type",
+                                                     type3.chassis_type);
+            if (type3.chassis_type > UINT8_MAX) {
+                error_setg(errp, "SMBIOS chassis type is too large (> %d)",
+                           UINT8_MAX);
+            }
             return;
         case 4:
             if (!qemu_opts_validate(opts, qemu_smbios_type4_opts, errp)) {