From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.xen@gmail.com>
Subject: Re: [PATCH] x86: machine_restart() must not call
 acpi_dmar_reinstate() twice
Date: Fri, 13 Sep 2013 03:14:36 -0700
Message-ID: <CE58339C.5DCA7%keir.xen@gmail.com>
References: <5232E3EF02000078000F2F35@nat28.tlf.novell.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xen.org>
Received: from mail6.bemta4.messagelabs.com ([85.158.143.247])
	by lists.xen.org with esmtp (Exim 4.72)
	(envelope-from <keir.xen@gmail.com>) id 1VKQOj-0008Tb-1W
	for xen-devel@lists.xenproject.org; Fri, 13 Sep 2013 10:14:45 +0000
Received: by mail-pd0-f178.google.com with SMTP id w10so1042955pde.23
	for <xen-devel@lists.xenproject.org>;
	Fri, 13 Sep 2013 03:14:41 -0700 (PDT)
In-Reply-To: <5232E3EF02000078000F2F35@nat28.tlf.novell.com>
List-Unsubscribe: <http://lists.xen.org/cgi-bin/mailman/options/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xen.org>
List-Help: <mailto:xen-devel-request@lists.xen.org?subject=help>
List-Subscribe: <http://lists.xen.org/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=subscribe>
Sender: xen-devel-bounces@lists.xen.org
Errors-To: xen-devel-bounces@lists.xen.org
To: Jan Beulich <JBeulich@suse.com>, xen-devel <xen-devel@lists.xenproject.org>
List-Id: xen-devel@lists.xenproject.org

On 13/09/2013 01:07, "Jan Beulich" <JBeulich@suse.com> wrote:

> .. as that function is not idempotent (it always alters the table
> checksum). The (generally) duplicate call was a result from it being
> made before machine_restart() re-invoking itself on the boot CPU.
> 
> Considering that no problem arose so far from the table corruption I
> doubt that we need to restore the correct table signature on the
> reboot path in general. The only case I can see this as potentially
> necessary is the tboot one, hence do the call just in that case.
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Acked-by: Keir Fraser <keir@xen.org>

> ---
> Note that this was found to be particularly an issue backporting
> 2ee9cbf9 ("ACPI: fix acpi_os_map_memory()") to 4.1.x: The first
> invocation would acquire the lock in acpi_os_map_memory(), and since
> the lock never gets released, the second invocation gets stuck.
> 
> --- a/xen/arch/x86/shutdown.c
> +++ b/xen/arch/x86/shutdown.c
> @@ -470,8 +470,6 @@ void machine_restart(unsigned int delay_
>      console_start_sync();
>      spin_debug_disable();
>  
> -    acpi_dmar_reinstate();
> -
>      local_irq_enable();
>  
>      /* Ensure we are the boot CPU. */
> @@ -496,7 +494,10 @@ void machine_restart(unsigned int delay_
>      mdelay(delay_millisecs);
>  
>      if ( tboot_in_measured_env() )
> +    {
> +        acpi_dmar_reinstate();
>          tboot_shutdown(TB_SHUTDOWN_REBOOT);
> +    }
>  
>      efi_reset_system(reboot_mode != 0);
>  
> 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel