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>

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 = {

hw/i386/pc_sysfw.c

@@ -39,15 +39,6 @@
 #include "hw/block/flash.h"
 #include "sysemu/kvm.h"
 
-/*
- * 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.
- */
-#define FLASH_SIZE_LIMIT (8 * MiB)
-
 #define FLASH_SECTOR_SIZE 4096
 
 static void pc_isa_bios_init(MemoryRegion *rom_memory,
@@ -140,7 +131,7 @@ void pc_system_flash_cleanup_unused(PCMachineState *pcms)
  * Stop at the first pcms->flash[0] lacking a block backend.
  * Set each flash's size from its block backend.  Fatal error if the
  * size isn't a non-zero multiple of 4KiB, or the total size exceeds
- * FLASH_SIZE_LIMIT.
+ * pcms->max_fw_size.
  *
  * If pcms->flash[0] has a block backend, its memory is passed to
  * pc_isa_bios_init().  Merging several flash devices for isa-bios is
@@ -182,10 +173,10 @@ static void pc_system_flash_map(PCMachineState *pcms,
         }
         if ((hwaddr)size != size
             || total_size > HWADDR_MAX - size
-            || total_size + size > FLASH_SIZE_LIMIT) {
+            || total_size + size > pcms->max_fw_size) {
             error_report("combined size of system firmware exceeds "
                          "%" PRIu64 " bytes",
-                         FLASH_SIZE_LIMIT);
+                         pcms->max_fw_size);
             exit(1);
         }
 

include/hw/i386/pc.h

@@ -44,6 +44,7 @@ typedef struct PCMachineState {
     bool sata_enabled;
     bool pit_enabled;
     bool hpet_enabled;
+    uint64_t max_fw_size;
 
     /* NUMA information: */
     uint64_t numa_nodes;
@@ -60,6 +61,7 @@ typedef struct PCMachineState {
 #define PC_MACHINE_SMBUS            "smbus"
 #define PC_MACHINE_SATA             "sata"
 #define PC_MACHINE_PIT              "pit"
+#define PC_MACHINE_MAX_FW_SIZE      "max-fw-size"
 
 /**
  * PCMachineClass: