This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] [PATCH] x86: extend runstate area updates

To: Jan Beulich <JBeulich@xxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] x86: extend runstate area updates
From: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
Date: Fri, 20 Nov 2009 18:57:18 +0000
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Fri, 20 Nov 2009 10:57:58 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <1258740598.1022.185.camel@xxxxxxxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Organization: Citrix Systems, Inc.
References: <4A8ABF4B020000780001049A@xxxxxxxxxxxxxxxxxx> <1258740598.1022.185.camel@xxxxxxxxxxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
On Fri, 2009-11-20 at 18:09 +0000, Ian Campbell wrote:
> I can't see where the guest runstate pointer is supposed to be either
> restored or re-setup on resume. I tried adding a setup_runstate_info
> to xen_timer_resume (to match the call in xen_timer_setup) but that
> seems like it is already too late -- I still see the warnings trigger.
> I'm not sure how this is possible since I thought we were in a
> stop_machine section at this point.

The xen_sched_clock calls are as a result of the various printks, e.g.
in xen_vcpu_setup, in order to add the timestamp to the output.
Therefore we need to ensure we reset the runstate info before any


Subject: re-register runstate area earlier on resume.

This is necessary to ensure the runstate area is available to
xen_sched_clock before any calls to printk which will require it in
order to provide a timestamp.

I chose to pull the xen_setup_runstate_info out of xen_time_init into
the caller in order to maintain parity with calling
xen_setup_runstate_info separately from calling xen_time_resume.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 0a5aa44..fed538a 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -100,7 +102,7 @@ bool xen_vcpu_stolen(int vcpu)
        return per_cpu(runstate, vcpu).state == RUNSTATE_runnable;
-static void setup_runstate_info(int cpu)
+void xen_setup_runstate_info(int cpu)
        struct vcpu_register_runstate_memory_area area;
@@ -442,8 +456,6 @@ void xen_setup_timer(int cpu)
        evt->cpumask = cpumask_of(cpu);
        evt->irq = irq;
-       setup_runstate_info(cpu);
 void xen_teardown_timer(int cpu)
@@ -494,6 +507,7 @@ __init void xen_time_init(void)
+       xen_setup_runstate_info(cpu);
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index ca6596b..07ee25c 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -44,6 +44,7 @@ void __init xen_build_dynamic_phys_to_machine(void);
 void xen_init_irq_ops(void);
 void xen_setup_timer(int cpu);
+void xen_setup_runstate_info(int cpu);
 void xen_teardown_timer(int cpu);
 cycle_t xen_clocksource_read(void);
 void xen_setup_cpu_clockevents(void);
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index f09e8c3..219fb3f 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -145,6 +158,8 @@ void xen_vcpu_restore(void)
                            HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL))
+                       xen_setup_runstate_info(cpu);
                        if (other_cpu &&

Xen-devel mailing list