hw/i386/pc: add max combined fw size as machine configuration option

At Hewlett Packard Inc. we have a need for increased fw size to enable testing of our custom fw.

Rebase v6 patch to d73c46e4

Signed-off-by: Erich McMillan <erich.mcmillan@hp.com>
Message-Id: <20201208155338.14-1-erich.mcmillan@hp.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 51 insertions, 0 deletions

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 7113fb0770..675e15c0aa 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1569,6 +1569,50 @@ static void pc_machine_set_max_ram_below_4g(Object *obj, Visitor *v,
     pcms->max_ram_below_4g = value;
 }
 
+static void pc_machine_get_max_fw_size(Object *obj, Visitor *v,
+                                       const char *name, void *opaque,
+                                       Error **errp)
+{
+    PCMachineState *pcms = PC_MACHINE(obj);
+    uint64_t value = pcms->max_fw_size;
+
+    visit_type_size(v, name, &value, errp);
+}
+
+static void pc_machine_set_max_fw_size(Object *obj, Visitor *v,
+                                       const char *name, void *opaque,
+                                       Error **errp)
+{
+    PCMachineState *pcms = PC_MACHINE(obj);
+    Error *error = NULL;
+    uint64_t value;
+
+    visit_type_size(v, name, &value, &error);
+    if (error) {
+        error_propagate(errp, error);
+        return;
+    }
+
+    /*
+    * We don't have a theoretically justifiable exact lower bound on the base
+    * address of any flash mapping. In practice, the IO-APIC MMIO range is
+    * [0xFEE00000..0xFEE01000] -- see IO_APIC_DEFAULT_ADDRESS --, leaving free
+    * only 18MB-4KB below 4G. For now, restrict the cumulative mapping to 8MB in
+    * size.
+    */
+    if (value > 16 * MiB) {
+        error_setg(errp,
+                   "User specified max allowed firmware size %" PRIu64 " is "
+                   "greater than 16MiB. If combined firwmare size exceeds "
+                   "16MiB the system may not boot, or experience intermittent"
+                   "stability issues.",
+                   value);
+        return;
+    }
+
+    pcms->max_fw_size = value;
+}
+
 static void pc_machine_initfn(Object *obj)
 {
     PCMachineState *pcms = PC_MACHINE(obj);
@@ -1584,6 +1628,7 @@ static void pc_machine_initfn(Object *obj)
     pcms->smbus_enabled = true;
     pcms->sata_enabled = true;
     pcms->pit_enabled = true;
+    pcms->max_fw_size = 8 * MiB;
 #ifdef CONFIG_HPET
     pcms->hpet_enabled = true;
 #endif
@@ -1710,6 +1755,12 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
 
     object_class_property_add_bool(oc, "hpet",
         pc_machine_get_hpet, pc_machine_set_hpet);
+
+    object_class_property_add(oc, PC_MACHINE_MAX_FW_SIZE, "size",
+        pc_machine_get_max_fw_size, pc_machine_set_max_fw_size,
+        NULL, NULL);
+    object_class_property_set_description(oc, PC_MACHINE_MAX_FW_SIZE,
+        "Maximum combined firmware size");
 }
 
 static const TypeInfo pc_machine_info = {