* [PATCH] x86/xen: Disable APIC PM for Xen PV guests
@ 2014-03-04 2:40 Boris Ostrovsky
2014-03-04 10:25 ` David Vrabel
2014-03-17 17:10 ` Boris Ostrovsky
0 siblings, 2 replies; 4+ messages in thread
From: Boris Ostrovsky @ 2014-03-04 2:40 UTC (permalink / raw)
To: tglx, mingo, hpa, konrad.wilk, david.vrabel
Cc: xen-devel, linux-kernel, boris.ostrovsky
Xen PV guests support only few APIC registers and writes to
unsupported registers result in WARN_ONs. Most APIC accesses in these
guests have been eliminated; however, lapic_suspend/resume are still
called (on 32-bit kernels).
We can disable APIC power management in xen_smp_prepare_boot_cpu()
(which is called after APIC has been initialized).
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
arch/x86/include/asm/apic.h | 2 ++
arch/x86/kernel/apic/apic.c | 6 ++++++
arch/x86/xen/smp.c | 4 ++++
3 files changed, 12 insertions(+)
An alternative could be to add another op to stuct apic. The advantage would be
the fact that we never have a window of time when APIC PM is enabled. The downside
is having yet another op (of which there are already plenty).
We could also avoid loading lapic_syscore_ops but I couldn't think of a good way
to figure out when not to do it.
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 1d2091a..1f100f2 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -687,6 +687,8 @@ extern int default_cpu_present_to_apicid(int mps_cpu);
extern int default_check_phys_apicid_present(int phys_apicid);
#endif
+extern void apic_pm_deactivate(void);
+
#endif /* CONFIG_X86_LOCAL_APIC */
extern void irq_enter(void);
extern void irq_exit(void);
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 7f26c9a..60607b3 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2424,6 +2424,11 @@ static void apic_pm_activate(void)
apic_pm_state.active = 1;
}
+void apic_pm_deactivate(void)
+{
+ apic_pm_state.active = 0;
+}
+
static int __init init_lapic_sysfs(void)
{
/* XXX: remove suspend/resume procs if !apic_pm_state.active? */
@@ -2439,6 +2444,7 @@ core_initcall(init_lapic_sysfs);
#else /* CONFIG_PM */
static void apic_pm_activate(void) { }
+void apic_pm_deactivate(void) { }
#endif /* CONFIG_PM */
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index a18eadd..33115d8 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -298,6 +298,10 @@ static void __init xen_smp_prepare_boot_cpu(void)
xen_filter_cpu_maps();
xen_setup_vcpu_info_placement();
+
+#ifdef CONFIG_X86_LOCAL_APIC
+ apic_pm_deactivate();
+#endif
}
/*
* The alternative logic (which patches the unlock/lock) runs before
--
1.7.10.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] x86/xen: Disable APIC PM for Xen PV guests
2014-03-04 2:40 [PATCH] x86/xen: Disable APIC PM for Xen PV guests Boris Ostrovsky
@ 2014-03-04 10:25 ` David Vrabel
2014-03-04 21:17 ` Boris Ostrovsky
2014-03-17 17:10 ` Boris Ostrovsky
1 sibling, 1 reply; 4+ messages in thread
From: David Vrabel @ 2014-03-04 10:25 UTC (permalink / raw)
To: Boris Ostrovsky; +Cc: tglx, mingo, hpa, konrad.wilk, xen-devel, linux-kernel
On 04/03/14 02:40, Boris Ostrovsky wrote:
> Xen PV guests support only few APIC registers and writes to
> unsupported registers result in WARN_ONs. Most APIC accesses in these
> guests have been eliminated; however, lapic_suspend/resume are still
> called (on 32-bit kernels).
>
> We can disable APIC power management in xen_smp_prepare_boot_cpu()
> (which is called after APIC has been initialized).
Having looked at another APIC related problem recently, I wonder if Xen
would be better served by having its own APIC driver instead of trying
to piggy-back of some hardware one which doesn't do what we want.
David
>
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> ---
> arch/x86/include/asm/apic.h | 2 ++
> arch/x86/kernel/apic/apic.c | 6 ++++++
> arch/x86/xen/smp.c | 4 ++++
> 3 files changed, 12 insertions(+)
>
>
> An alternative could be to add another op to stuct apic. The advantage would be
> the fact that we never have a window of time when APIC PM is enabled. The downside
> is having yet another op (of which there are already plenty).
>
> We could also avoid loading lapic_syscore_ops but I couldn't think of a good way
> to figure out when not to do it.
>
>
>
> diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
> index 1d2091a..1f100f2 100644
> --- a/arch/x86/include/asm/apic.h
> +++ b/arch/x86/include/asm/apic.h
> @@ -687,6 +687,8 @@ extern int default_cpu_present_to_apicid(int mps_cpu);
> extern int default_check_phys_apicid_present(int phys_apicid);
> #endif
>
> +extern void apic_pm_deactivate(void);
> +
> #endif /* CONFIG_X86_LOCAL_APIC */
> extern void irq_enter(void);
> extern void irq_exit(void);
> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
> index 7f26c9a..60607b3 100644
> --- a/arch/x86/kernel/apic/apic.c
> +++ b/arch/x86/kernel/apic/apic.c
> @@ -2424,6 +2424,11 @@ static void apic_pm_activate(void)
> apic_pm_state.active = 1;
> }
>
> +void apic_pm_deactivate(void)
> +{
> + apic_pm_state.active = 0;
> +}
> +
> static int __init init_lapic_sysfs(void)
> {
> /* XXX: remove suspend/resume procs if !apic_pm_state.active? */
> @@ -2439,6 +2444,7 @@ core_initcall(init_lapic_sysfs);
> #else /* CONFIG_PM */
>
> static void apic_pm_activate(void) { }
> +void apic_pm_deactivate(void) { }
>
> #endif /* CONFIG_PM */
>
> diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
> index a18eadd..33115d8 100644
> --- a/arch/x86/xen/smp.c
> +++ b/arch/x86/xen/smp.c
> @@ -298,6 +298,10 @@ static void __init xen_smp_prepare_boot_cpu(void)
>
> xen_filter_cpu_maps();
> xen_setup_vcpu_info_placement();
> +
> +#ifdef CONFIG_X86_LOCAL_APIC
> + apic_pm_deactivate();
> +#endif
> }
> /*
> * The alternative logic (which patches the unlock/lock) runs before
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] x86/xen: Disable APIC PM for Xen PV guests
2014-03-04 10:25 ` David Vrabel
@ 2014-03-04 21:17 ` Boris Ostrovsky
0 siblings, 0 replies; 4+ messages in thread
From: Boris Ostrovsky @ 2014-03-04 21:17 UTC (permalink / raw)
To: David Vrabel; +Cc: tglx, mingo, hpa, konrad.wilk, xen-devel, linux-kernel
On 03/04/2014 05:25 AM, David Vrabel wrote:
> On 04/03/14 02:40, Boris Ostrovsky wrote:
>> Xen PV guests support only few APIC registers and writes to
>> unsupported registers result in WARN_ONs. Most APIC accesses in these
>> guests have been eliminated; however, lapic_suspend/resume are still
>> called (on 32-bit kernels).
>>
>> We can disable APIC power management in xen_smp_prepare_boot_cpu()
>> (which is called after APIC has been initialized).
> Having looked at another APIC related problem recently, I wonder if Xen
> would be better served by having its own APIC driver instead of trying
> to piggy-back of some hardware one which doesn't do what we want.
Possibly, although I don't think it will help with this particular issue
since this patch is trying to address a problem in non-privileged
guests. Such guests don't have ACPI enabled and so no APIC probing is
done for them.
-boris
>
> David
>
>> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
>> ---
>> arch/x86/include/asm/apic.h | 2 ++
>> arch/x86/kernel/apic/apic.c | 6 ++++++
>> arch/x86/xen/smp.c | 4 ++++
>> 3 files changed, 12 insertions(+)
>>
>>
>> An alternative could be to add another op to stuct apic. The advantage would be
>> the fact that we never have a window of time when APIC PM is enabled. The downside
>> is having yet another op (of which there are already plenty).
>>
>> We could also avoid loading lapic_syscore_ops but I couldn't think of a good way
>> to figure out when not to do it.
>>
>>
>>
>> diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
>> index 1d2091a..1f100f2 100644
>> --- a/arch/x86/include/asm/apic.h
>> +++ b/arch/x86/include/asm/apic.h
>> @@ -687,6 +687,8 @@ extern int default_cpu_present_to_apicid(int mps_cpu);
>> extern int default_check_phys_apicid_present(int phys_apicid);
>> #endif
>>
>> +extern void apic_pm_deactivate(void);
>> +
>> #endif /* CONFIG_X86_LOCAL_APIC */
>> extern void irq_enter(void);
>> extern void irq_exit(void);
>> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
>> index 7f26c9a..60607b3 100644
>> --- a/arch/x86/kernel/apic/apic.c
>> +++ b/arch/x86/kernel/apic/apic.c
>> @@ -2424,6 +2424,11 @@ static void apic_pm_activate(void)
>> apic_pm_state.active = 1;
>> }
>>
>> +void apic_pm_deactivate(void)
>> +{
>> + apic_pm_state.active = 0;
>> +}
>> +
>> static int __init init_lapic_sysfs(void)
>> {
>> /* XXX: remove suspend/resume procs if !apic_pm_state.active? */
>> @@ -2439,6 +2444,7 @@ core_initcall(init_lapic_sysfs);
>> #else /* CONFIG_PM */
>>
>> static void apic_pm_activate(void) { }
>> +void apic_pm_deactivate(void) { }
>>
>> #endif /* CONFIG_PM */
>>
>> diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
>> index a18eadd..33115d8 100644
>> --- a/arch/x86/xen/smp.c
>> +++ b/arch/x86/xen/smp.c
>> @@ -298,6 +298,10 @@ static void __init xen_smp_prepare_boot_cpu(void)
>>
>> xen_filter_cpu_maps();
>> xen_setup_vcpu_info_placement();
>> +
>> +#ifdef CONFIG_X86_LOCAL_APIC
>> + apic_pm_deactivate();
>> +#endif
>> }
>> /*
>> * The alternative logic (which patches the unlock/lock) runs before
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] x86/xen: Disable APIC PM for Xen PV guests
2014-03-04 2:40 [PATCH] x86/xen: Disable APIC PM for Xen PV guests Boris Ostrovsky
2014-03-04 10:25 ` David Vrabel
@ 2014-03-17 17:10 ` Boris Ostrovsky
1 sibling, 0 replies; 4+ messages in thread
From: Boris Ostrovsky @ 2014-03-17 17:10 UTC (permalink / raw)
To: tglx, mingo, hpa
Cc: Boris Ostrovsky, konrad.wilk, david.vrabel, xen-devel, linux-kernel
On 03/03/2014 09:40 PM, Boris Ostrovsky wrote:
> Xen PV guests support only few APIC registers and writes to
> unsupported registers result in WARN_ONs. Most APIC accesses in these
> guests have been eliminated; however, lapic_suspend/resume are still
> called (on 32-bit kernels).
>
> We can disable APIC power management in xen_smp_prepare_boot_cpu()
> (which is called after APIC has been initialized).
This touches generic APIC code so x86 maintainers' review would
be appreciated.
Thanks.
-boris
> Signed-off-by: Boris Ostrovsky<boris.ostrovsky@oracle.com>
> ---
> arch/x86/include/asm/apic.h | 2 ++
> arch/x86/kernel/apic/apic.c | 6 ++++++
> arch/x86/xen/smp.c | 4 ++++
> 3 files changed, 12 insertions(+)
>
>
> An alternative could be to add another op to stuct apic. The advantage would be
> the fact that we never have a window of time when APIC PM is enabled. The downside
> is having yet another op (of which there are already plenty).
>
> We could also avoid loading lapic_syscore_ops but I couldn't think of a good way
> to figure out when not to do it.
>
>
>
> diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
> index 1d2091a..1f100f2 100644
> --- a/arch/x86/include/asm/apic.h
> +++ b/arch/x86/include/asm/apic.h
> @@ -687,6 +687,8 @@ extern int default_cpu_present_to_apicid(int mps_cpu);
> extern int default_check_phys_apicid_present(int phys_apicid);
> #endif
>
> +extern void apic_pm_deactivate(void);
> +
> #endif /* CONFIG_X86_LOCAL_APIC */
> extern void irq_enter(void);
> extern void irq_exit(void);
> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
> index 7f26c9a..60607b3 100644
> --- a/arch/x86/kernel/apic/apic.c
> +++ b/arch/x86/kernel/apic/apic.c
> @@ -2424,6 +2424,11 @@ static void apic_pm_activate(void)
> apic_pm_state.active = 1;
> }
>
> +void apic_pm_deactivate(void)
> +{
> + apic_pm_state.active = 0;
> +}
> +
> static int __init init_lapic_sysfs(void)
> {
> /* XXX: remove suspend/resume procs if !apic_pm_state.active? */
> @@ -2439,6 +2444,7 @@ core_initcall(init_lapic_sysfs);
> #else /* CONFIG_PM */
>
> static void apic_pm_activate(void) { }
> +void apic_pm_deactivate(void) { }
>
> #endif /* CONFIG_PM */
>
> diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
> index a18eadd..33115d8 100644
> --- a/arch/x86/xen/smp.c
> +++ b/arch/x86/xen/smp.c
> @@ -298,6 +298,10 @@ static void __init xen_smp_prepare_boot_cpu(void)
>
> xen_filter_cpu_maps();
> xen_setup_vcpu_info_placement();
> +
> +#ifdef CONFIG_X86_LOCAL_APIC
> + apic_pm_deactivate();
> +#endif
> }
> /*
> * The alternative logic (which patches the unlock/lock) runs before
^ permalink raw reply [flat|nested] 4+ messages in thread
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2014-03-04 2:40 [PATCH] x86/xen: Disable APIC PM for Xen PV guests Boris Ostrovsky
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2014-03-17 17:10 ` Boris Ostrovsky
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