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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

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
printks.

--- 

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)
 
        setup_force_cpu_cap(X86_FEATURE_TSC);
 
+       xen_setup_runstate_info(cpu);
        xen_setup_timer(cpu);
        xen_setup_cpu_clockevents();
 }
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))
                                BUG();
 
+                       xen_setup_runstate_info(cpu);
+
                        xen_vcpu_setup(cpu);
 
                        if (other_cpu &&



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