hw/riscv: Load OpenSBI as the default firmware

If the user hasn't specified a firmware to load (with -bios) or
specified no bios (with -bios none) then load OpenSBI by default. This
allows users to boot a RISC-V kernel with just -kernel.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

3 files changed, 66 insertions, 6 deletions

diff --git a/hw/riscv/boot.c b/hw/riscv/boot.c
index ff023f42d0..5dee63011b 100644
--- a/hw/riscv/boot.c
+++ b/hw/riscv/boot.c
@@ -18,6 +18,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu-common.h"
 #include "qemu/units.h"
 #include "qemu/error-report.h"
 #include "exec/cpu-defs.h"
@@ -32,6 +33,59 @@
 # define KERNEL_BOOT_ADDRESS 0x80200000
 #endif
 
+void riscv_find_and_load_firmware(MachineState *machine,
+                                  const char *default_machine_firmware,
+                                  hwaddr firmware_load_addr)
+{
+    char *firmware_filename;
+
+    if (!machine->firmware) {
+        /*
+         * The user didn't specify -bios.
+         * At the moment we default to loading nothing when this hapens.
+         * In the future this defaul will change to loading the prebuilt
+         * OpenSBI firmware. Let's warn the user and then continue.
+        */
+        warn_report("No -bios option specified. Not loading a firmware.");
+        warn_report("This default will change in QEMU 4.3. Please use the " \
+                    "-bios option to aviod breakages when this happens.");
+        warn_report("See QEMU's deprecation documentation for details");
+        return;
+    }
+
+    if (!strcmp(machine->firmware, "default")) {
+        /*
+         * The user has specified "-bios default". That means we are going to
+         * load the OpenSBI binary included in the QEMU source.
+         *
+         * We can't load the binary by default as it will break existing users
+         * as users are already loading their own firmware.
+         *
+         * Let's try to get everyone to specify the -bios option at all times,
+         * so then in the future we can make "-bios default" the default option
+         * if no -bios option is set without breaking anything.
+         */
+        firmware_filename = qemu_find_file(QEMU_FILE_TYPE_BIOS,
+                                           default_machine_firmware);
+        if (firmware_filename == NULL) {
+            error_report("Unable to load the default RISC-V firmware \"%s\"",
+                         default_machine_firmware);
+            exit(1);
+        }
+    } else {
+        firmware_filename = machine->firmware;
+    }
+
+    if (strcmp(firmware_filename, "none")) {
+        /* If not "none" load the firmware */
+        riscv_load_firmware(firmware_filename, firmware_load_addr);
+    }
+
+    if (!strcmp(machine->firmware, "default")) {
+        g_free(firmware_filename);
+    }
+}
+
 target_ulong riscv_load_firmware(const char *firmware_filename,
                                  hwaddr firmware_load_addr)
 {
diff --git a/hw/riscv/sifive_u.c b/hw/riscv/sifive_u.c
index ca53a9290d..71b8083c05 100644
--- a/hw/riscv/sifive_u.c
+++ b/hw/riscv/sifive_u.c
@@ -49,6 +49,8 @@
 
 #include <libfdt.h>
 
+#define BIOS_FILENAME "opensbi-riscv64-sifive_u-fw_jump.bin"
+
 static const struct MemmapEntry {
     hwaddr base;
     hwaddr size;
@@ -269,9 +271,8 @@ static void riscv_sifive_u_init(MachineState *machine)
     /* create device tree */
     create_fdt(s, memmap, machine->ram_size, machine->kernel_cmdline);
 
-    if (machine->firmware) {
-        riscv_load_firmware(machine->firmware, memmap[SIFIVE_U_DRAM].base);
-    }
+    riscv_find_and_load_firmware(machine, BIOS_FILENAME,
+                                 memmap[SIFIVE_U_DRAM].base);
 
     if (machine->kernel_filename) {
         riscv_load_kernel(machine->kernel_filename);
diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
index ecdc77d728..25faf3b417 100644
--- a/hw/riscv/virt.c
+++ b/hw/riscv/virt.c
@@ -44,6 +44,12 @@
 
 #include <libfdt.h>
 
+#if defined(TARGET_RISCV32)
+# define BIOS_FILENAME "opensbi-riscv32-virt-fw_jump.bin"
+#else
+# define BIOS_FILENAME "opensbi-riscv64-virt-fw_jump.bin"
+#endif
+
 static const struct MemmapEntry {
     hwaddr base;
     hwaddr size;
@@ -399,9 +405,8 @@ static void riscv_virt_board_init(MachineState *machine)
     memory_region_add_subregion(system_memory, memmap[VIRT_MROM].base,
                                 mask_rom);
 
-    if (machine->firmware) {
-        riscv_load_firmware(machine->firmware, memmap[VIRT_DRAM].base);
-    }
+    riscv_find_and_load_firmware(machine, BIOS_FILENAME,
+                                 memmap[VIRT_DRAM].base);
 
     if (machine->kernel_filename) {
         uint64_t kernel_entry = riscv_load_kernel(machine->kernel_filename);