Re: [PATCH] x86: improve "PCI reset register" rebooting

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 13/03/15 10:41, Jan Beulich wrote:
> The way this method works allows for honoring "warm" reboot requested
> by the user and additionally has a way to power-cycle the machine.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>
> --- a/docs/misc/xen-command-line.markdown
> +++ b/docs/misc/xen-command-line.markdown
> @@ -1117,7 +1117,7 @@ The following resources are available:
>    * `rmid_max` indicates the max value for rmid.
>  
>  ### reboot
> -> `= t[riple] | k[bd] | a[cpi] | p[ci] | e[fi] | n[o] [, [w]arm | [c]old]`
> +> `= t[riple] | k[bd] | a[cpi] | p[ci] | P[ower] | e[fi] | n[o] [, [w]arm | [c]old]`
>  
>  > Default: `0`
>  
> @@ -1137,6 +1137,8 @@ Specify the host reboot method.
>  
>  `pci` instructs Xen to reboot the host using PCI reset register (port CF9).
>  
> +`Power` instructs Xen to power-cycle the host using PCI reset register (port CF9).
> +
>  'efi' instructs Xen to reboot using the EFI reboot call (in EFI mode by
>   default it will use that method first).
>  
> --- a/xen/arch/x86/shutdown.c
> +++ b/xen/arch/x86/shutdown.c
> @@ -33,6 +33,7 @@ enum reboot_type {
>          BOOT_KBD = 'k',
>          BOOT_ACPI = 'a',
>          BOOT_CF9 = 'p',
> +        BOOT_CF9_PWR = 'P',
>          BOOT_EFI = 'e',
>  };
>  
> @@ -47,6 +48,7 @@ static int reboot_mode;
>   * kbd    Use the keyboard controller. cold reset (default)
>   * acpi   Use the RESET_REG in the FADT
>   * pci    Use the so-called "PCI reset register", CF9
> + * Power  Like 'pci' but for a full power-cyle reset
>   * efi    Use the EFI reboot (if running under EFI)
>   */
>  static enum reboot_type reboot_type = BOOT_INVALID;
> @@ -68,8 +70,9 @@ static void __init set_reboot_type(char 
>          case 'a':
>          case 'e':
>          case 'k':
> -        case 't':
> +        case 'P':
>          case 'p':
> +        case 't':
>              reboot_type = *str;
>              break;
>          }
> @@ -571,11 +574,18 @@ void machine_restart(unsigned int delay_
>              reboot_type = BOOT_KBD;
>              break;
>          case BOOT_CF9:
> +        case BOOT_CF9_PWR:
>              {
> -                u8 cf9 = inb(0xcf9) & ~6;
> -                outb(cf9|2, 0xcf9); /* Request hard reset */
> +                u8 cf9 = inb(0xcf9) & ~0x0e;
> +
> +                /* Request warm, hard, or power-cycle reset. */
> +                if ( reboot_type == BOOT_CF9_PWR )
> +                    cf9 |= 0x0a;
> +                else if ( reboot_mode == 0 )
> +                    cf9 |= 0x02;
> +                outb(cf9, 0xcf9);
>                  udelay(50);
> -                outb(cf9|6, 0xcf9); /* Actually do the reset */
> +                outb(cf9 | 0x04, 0xcf9); /* Actually do the reset. */

I would be nice to have some named constants (FULL_RST, RST_CPU and
SYS_RST is what the ICH10 manual uses), but the logic here does appear
correct.

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

>                  udelay(50);
>              }
>              reboot_type = BOOT_ACPI;
>
>
>