1 files changed, 27 insertions, 7 deletions

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 34f8d37ae3c5..ddc93891cdcd 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -29,14 +29,17 @@ EXPORT_SYMBOL(pm_power_off);
 
 static const struct desc_ptr no_idt = {};
 static int reboot_mode;
-enum reboot_type reboot_type = BOOT_KBD;
+enum reboot_type reboot_type = BOOT_CF9_COND;
 int reboot_force;
 
 #if defined(CONFIG_X86_32) && defined(CONFIG_SMP)
 static int reboot_cpu = -1;
 #endif
 
-/* reboot=b[ios] | s[mp] | t[riple] | k[bd] | e[fi] [, [w]arm | [c]old]
+/* This is set by the PCI code if either type 1 or type 2 PCI is detected */
+bool port_cf9_safe = false;
+
+/* reboot=b[ios] | s[mp] | t[riple] | k[bd] | e[fi] [, [w]arm | [c]old] | p[ci]
    warm   Don't set the cold reboot flag
    cold   Set the cold reboot flag
    bios   Reboot by jumping through the BIOS (only for X86_32)
@@ -45,6 +48,7 @@ static int reboot_cpu = -1;
    kbd    Use the keyboard controller. cold reset (default)
    acpi   Use the RESET_REG in the FADT
    efi    Use efi reset_system runtime service
+   pci    Use the so-called "PCI reset register", CF9
    force  Avoid anything that could hang.
  */
 static int __init reboot_setup(char *str)
@@ -79,6 +83,7 @@ static int __init reboot_setup(char *str)
                 case 'k':
                 case 't':
                 case 'e':
+                case 'p':
                         reboot_type = *str;
                         break;
 
@@ -379,28 +384,43 @@ static void native_machine_emergency_restart(void)
                         load_idt(&no_idt);
                         __asm__ __volatile__("int3");
 
-                        reboot_type = BOOT_KBD;
+                        reboot_type = BOOT_CF9_COND;
                         break;
 
 #ifdef CONFIG_X86_32
                 case BOOT_BIOS:
                         machine_real_restart(jump_to_bios, sizeof(jump_to_bios));
 
-                        reboot_type = BOOT_KBD;
+                        reboot_type = BOOT_CF9_COND;
                         break;
 #endif
 
                 case BOOT_ACPI:
                         acpi_reboot();
-                        reboot_type = BOOT_KBD;
+                        reboot_type = BOOT_CF9_COND;
                         break;
 
-
                 case BOOT_EFI:
                         if (efi_enabled)
-                                efi.reset_system(reboot_mode ? EFI_RESET_WARM : EFI_RESET_COLD,
+                                efi.reset_system(reboot_mode ?
+                                                 EFI_RESET_WARM :
+                                                 EFI_RESET_COLD,
                                                  EFI_SUCCESS, 0, NULL);
+                        reboot_type = BOOT_CF9_COND;
+                        break;
+
+                case BOOT_CF9:
+                        port_cf9_safe = true;
+                        /* fall through */
 
+                case BOOT_CF9_COND:
+                        if (port_cf9_safe) {
+                                u8 cf9 = inb(0xcf9) & ~6;
+                                outb(cf9|2, 0xcf9); /* Request hard reset */
+                                udelay(50);
+                                outb(cf9|6, 0xcf9); /* Actually do the reset */
+                                udelay(50);
+                        }
                         reboot_type = BOOT_KBD;
                         break;
                 }