This parameter is to be used in the processor_id entry in the type 4
table.

This parameter is set as optional and if left will use the values from
the CPU model.

This enables hiding the host information from the guest and allowing AMD
VMs to run pretending to be Intel for some userspace software concerns.

Reviewed-by: Peter Foley <pefoley@google.com>
Reviewed-by: Titus Rwantare <titusr@google.com>
Signed-off-by: Patrick Venture <venture@google.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
---
v3: updated commit message to match v2
v2: Added to SRST options list, upgraded to full 64-bit value.
---
 hw/smbios/smbios.c | 19 ++++++++++++++++---
 qemu-options.hx    |  3 ++-
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/hw/smbios/smbios.c b/hw/smbios/smbios.c
index 7397e56737..385b69b0c9 100644
--- a/hw/smbios/smbios.c
+++ b/hw/smbios/smbios.c
@@ -104,9 +104,11 @@ static struct {
     const char *sock_pfx, *manufacturer, *version, *serial, *asset, *part;
     uint64_t max_speed;
     uint64_t current_speed;
+    uint64_t processor_id;
 } type4 = {
     .max_speed = DEFAULT_CPU_SPEED,
-    .current_speed = DEFAULT_CPU_SPEED
+    .current_speed = DEFAULT_CPU_SPEED,
+    .processor_id = 0,
 };
 
 static struct {
@@ -327,6 +329,10 @@ static const QemuOptDesc qemu_smbios_type4_opts[] = {
         .name = "part",
         .type = QEMU_OPT_STRING,
         .help = "part number",
+    }, {
+        .name = "processor-id",
+        .type = QEMU_OPT_NUMBER,
+        .help = "processor id",
     },
     { /* end of list */ }
 };
@@ -669,8 +675,13 @@ static void smbios_build_type_4_table(MachineState *ms, unsigned instance)
     t->processor_type = 0x03; /* CPU */
     t->processor_family = 0x01; /* Other */
     SMBIOS_TABLE_SET_STR(4, processor_manufacturer_str, type4.manufacturer);
-    t->processor_id[0] = cpu_to_le32(smbios_cpuid_version);
-    t->processor_id[1] = cpu_to_le32(smbios_cpuid_features);
+    if (type4.processor_id == 0) {
+        t->processor_id[0] = cpu_to_le32(smbios_cpuid_version);
+        t->processor_id[1] = cpu_to_le32(smbios_cpuid_features);
+    } else {
+        t->processor_id[0] = cpu_to_le32((uint32_t)type4.processor_id);
+        t->processor_id[1] = cpu_to_le32(type4.processor_id >> 32);
+    }
     SMBIOS_TABLE_SET_STR(4, processor_version_str, type4.version);
     t->voltage = 0;
     t->external_clock = cpu_to_le16(0); /* Unknown */
@@ -1292,6 +1303,8 @@ void smbios_entry_add(QemuOpts *opts, Error **errp)
             save_opt(&type4.serial, opts, "serial");
             save_opt(&type4.asset, opts, "asset");
             save_opt(&type4.part, opts, "part");
+            /* If the value is 0, it will take the value from the CPU model. */
+            type4.processor_id = qemu_opt_get_number(opts, "processor-id", 0);
             type4.max_speed = qemu_opt_get_number(opts, "max-speed",
                                                   DEFAULT_CPU_SPEED);
             type4.current_speed = qemu_opt_get_number(opts, "current-speed",
diff --git a/qemu-options.hx b/qemu-options.hx
index ec90505d84..6256417935 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2527,6 +2527,7 @@ DEF("smbios", HAS_ARG, QEMU_OPTION_smbios,
     "                specify SMBIOS type 3 fields\n"
     "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n"
     "              [,asset=str][,part=str][,max-speed=%d][,current-speed=%d]\n"
+    "              [,processor-id=%d]\n"
     "                specify SMBIOS type 4 fields\n"
     "-smbios type=11[,value=str][,path=filename]\n"
     "                specify SMBIOS type 11 fields\n"
@@ -2552,7 +2553,7 @@ SRST
 ``-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str][,sku=str]``
     Specify SMBIOS type 3 fields
 
-``-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str][,asset=str][,part=str]``
+``-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str][,asset=str][,part=str][,processor-id=%d]``
     Specify SMBIOS type 4 fields
 
 ``-smbios type=11[,value=str][,path=filename]``
-- 
2.35.0.rc0.227.g00780c9af4-goog