hw/hppa: Fix booting Linux kernel with initrd

Commit 20f7b89 ("hw/hppa: Reset vCPUs calling resettable_reset()")
broke booting the Linux kernel with initrd which may have been provided
on the command line. The problem is, that the mentioned commit zeroes
out initial registers which were preset with addresses for the Linux
kernel and initrd.

Fix it by adding proper variables which are set shortly before starting
the firmware.

Signed-off-by: Helge Deller <deller@gmx.de>
Fixes: 20f7b89 ("hw/hppa: Reset vCPUs calling resettable_reset()")
Cc: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

Author: hdeller

hw/hppa/machine.c

@@ -356,7 +356,6 @@ static void machine_HP_common_init_tail(MachineState *machine, PCIBus *pci_bus,
     uint64_t kernel_entry = 0, kernel_low, kernel_high;
     MemoryRegion *addr_space = get_system_memory();
     MemoryRegion *rom_region;
-    unsigned int smp_cpus = machine->smp.cpus;
     SysBusDevice *s;
 
     /* SCSI disk setup. */
@@ -482,8 +481,8 @@ static void machine_HP_common_init_tail(MachineState *machine, PCIBus *pci_bus,
                       kernel_low, kernel_high, kernel_entry, size / KiB);
 
         if (kernel_cmdline) {
-            cpu[0]->env.gr[24] = 0x4000;
-            pstrcpy_targphys("cmdline", cpu[0]->env.gr[24],
+            cpu[0]->env.cmdline_or_bootorder = 0x4000;
+            pstrcpy_targphys("cmdline", cpu[0]->env.cmdline_or_bootorder,
                              TARGET_PAGE_SIZE, kernel_cmdline);
         }
 
@@ -513,32 +512,22 @@ static void machine_HP_common_init_tail(MachineState *machine, PCIBus *pci_bus,
             }
 
             load_image_targphys(initrd_filename, initrd_base, initrd_size);
-            cpu[0]->env.gr[23] = initrd_base;
-            cpu[0]->env.gr[22] = initrd_base + initrd_size;
+            cpu[0]->env.initrd_base = initrd_base;
+            cpu[0]->env.initrd_end  = initrd_base + initrd_size;
         }
     }
 
     if (!kernel_entry) {
         /* When booting via firmware, tell firmware if we want interactive
-         * mode (kernel_entry=1), and to boot from CD (gr[24]='d')
-         * or hard disc * (gr[24]='c').
+         * mode (kernel_entry=1), and to boot from CD (cmdline_or_bootorder='d')
+         * or hard disc (cmdline_or_bootorder='c').
          */
         kernel_entry = machine->boot_config.has_menu ? machine->boot_config.menu : 0;
-        cpu[0]->env.gr[24] = machine->boot_config.order[0];
+        cpu[0]->env.cmdline_or_bootorder = machine->boot_config.order[0];
     }
 
-    /* We jump to the firmware entry routine and pass the
-     * various parameters in registers. After firmware initialization,
-     * firmware will start the Linux kernel with ramdisk and cmdline.
-     */
-    cpu[0]->env.gr[26] = machine->ram_size;
-    cpu[0]->env.gr[25] = kernel_entry;
-
-    /* tell firmware how many SMP CPUs to present in inventory table */
-    cpu[0]->env.gr[21] = smp_cpus;
-
-    /* tell firmware fw_cfg port */
-    cpu[0]->env.gr[19] = FW_CFG_IO_BASE;
+    /* Keep initial kernel_entry for first boot */
+    cpu[0]->env.kernel_entry = kernel_entry;
 }
 
 /*
@@ -675,18 +664,19 @@ static void hppa_machine_reset(MachineState *ms, ResetType type)
         cpu[i]->env.gr[5] = CPU_HPA + i * 0x1000;
     }
 
-    /* already initialized by machine_hppa_init()? */
-    if (cpu[0]->env.gr[26] == ms->ram_size) {
-        return;
-    }
-
     cpu[0]->env.gr[26] = ms->ram_size;
-    cpu[0]->env.gr[25] = 0; /* no firmware boot menu */
-    cpu[0]->env.gr[24] = 'c';
-    /* gr22/gr23 unused, no initrd while reboot. */
+    cpu[0]->env.gr[25] = cpu[0]->env.kernel_entry;
+    cpu[0]->env.gr[24] = cpu[0]->env.cmdline_or_bootorder;
+    cpu[0]->env.gr[23] = cpu[0]->env.initrd_base;
+    cpu[0]->env.gr[22] = cpu[0]->env.initrd_end;
     cpu[0]->env.gr[21] = smp_cpus;
-    /* tell firmware fw_cfg port */
     cpu[0]->env.gr[19] = FW_CFG_IO_BASE;
+
+    /* reset static fields to avoid starting Linux kernel & initrd on reboot */
+    cpu[0]->env.kernel_entry = 0;
+    cpu[0]->env.initrd_base = 0;
+    cpu[0]->env.initrd_end = 0;
+    cpu[0]->env.cmdline_or_bootorder = 'c';
 }
 
 static void hppa_nmi(NMIState *n, int cpu_index, Error **errp)

target/hppa/cpu.h

@@ -268,6 +268,10 @@ typedef struct CPUArchState {
     struct {} end_reset_fields;
 
     bool is_pa20;
+
+    target_ulong kernel_entry; /* Linux kernel was loaded here */
+    target_ulong cmdline_or_bootorder;
+    target_ulong initrd_base, initrd_end;
 } CPUHPPAState;
 
 /**