riscv/virt: Jump to pflash if specified

If the user supplied pflash to QEMU then change the reset code to jump
to the pflash base address instead of the DRAM base address.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

hw/riscv/virt.c

@@ -443,6 +443,7 @@ static void riscv_virt_board_init(MachineState *machine)
     MemoryRegion *mask_rom = g_new(MemoryRegion, 1);
     char *plic_hart_config;
     size_t plic_hart_config_len;
+    target_ulong start_addr = memmap[VIRT_DRAM].base;
     int i;
     unsigned int smp_cpus = machine->smp.cpus;
 
@@ -489,6 +490,14 @@ static void riscv_virt_board_init(MachineState *machine)
         }
     }
 
+    if (drive_get(IF_PFLASH, 0, 0)) {
+        /*
+         * Pflash was supplied, let's overwrite the address we jump to after
+         * reset to the base of the flash.
+         */
+        start_addr = virt_memmap[VIRT_FLASH].base;
+    }
+
     /* reset vector */
     uint32_t reset_vec[8] = {
         0x00000297,                  /* 1:  auipc  t0, %pcrel_hi(dtb) */
@@ -501,7 +510,7 @@ static void riscv_virt_board_init(MachineState *machine)
 #endif
         0x00028067,                  /*     jr     t0 */
         0x00000000,
-        memmap[VIRT_DRAM].base,      /* start: .dword memmap[VIRT_DRAM].base */
+        start_addr,                  /* start: .dword */
         0x00000000,
                                      /* dtb: */
     };