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Date: Thu, 10 Dec 2009 19:30:55 +0300
From: Cyrill Gorcunov <gorcunov@openvz.org>
To: Ralf Hildebrandt <Ralf.Hildebrandt@charite.de>,
       linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
       x86team <x86@kernel.org>
Subject: Re: [2.6.32] WARNING: at arch/x86/kernel/apic/apic.c:249
	native_apic_write_dummy+0x30/0x3c()
Message-ID: <20091210163055.GD5086@lenovo>
References: <20091210154837.GT30903@charite.de> <20091210161335.GC5086@lenovo>
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On Thu, Dec 10, 2009 at 07:13:35PM +0300, Cyrill Gorcunov wrote:
> On Thu, Dec 10, 2009 at 04:48:37PM +0100, Ralf Hildebrandt wrote:
> > Running a vanilla 2.6.32 as Xen DomU, I'm getting:
> > 
> > [    0.000999] CPU: Physical Processor ID: 0
> > [    0.000999] CPU: Processor Core ID: 1
> > [    0.000999] Performance Events: AMD PMU driver.
> > [    0.000999] ------------[ cut here ]------------
> > [    0.000999] WARNING: at arch/x86/kernel/apic/apic.c:249 native_apic_write_dummy+0x30/0x3c()
> > [    0.000999] Modules linked in:
...

I suppose it should be something like the patch below.
Please test/review.
---
perf_event: check if we have APIC enabled on AMD cpu

Ralf Hildebrandt reported:

|
| Running a vanilla 2.6.32 as Xen DomU, I'm getting:
|
| [    0.000999] CPU: Physical Processor ID: 0
| [    0.000999] CPU: Processor Core ID: 1
| [    0.000999] Performance Events: AMD PMU driver.
| [    0.000999] ------------[ cut here ]------------
| [    0.000999] WARNING: at arch/x86/kernel/apic/apic.c:249 native_apic_write_dummy+0x30/0x3c()
| [    0.000999] Modules linked in:
| [    0.000999] Pid: 0, comm: swapper Not tainted 2.6.32 #3
| [    0.000999] Call Trace:
| [    0.000999]  [<ffffffff8102611a>] ? native_apic_write_dummy+0x30/0x3c
| [    0.000999]  [<ffffffff8104c5a2>] warn_slowpath_common+0x77/0x8f
| [    0.000999]  [<ffffffff8104c5c9>] warn_slowpath_null+0xf/0x11
| [    0.000999]  [<ffffffff8102611a>] native_apic_write_dummy+0x30/0x3c
| [    0.000999]  [<ffffffff8101bf49>] perf_events_lapic_init+0x2e/0x30
| [    0.000999]  [<ffffffff818cc6fe>] init_hw_perf_events+0x300/0x39d
| [    0.000999]  [<ffffffff818cc25a>] identify_boot_cpu+0x3c/0x3e
| [    0.000999]  [<ffffffff818cc3da>] check_bugs+0x9/0x2d
| [    0.000999]  [<ffffffff818c4cae>] start_kernel+0x37a/0x38f
| [    0.000999]  [<ffffffff818c42c1>] x86_64_start_reservations+0xac/0xb0
| [    0.000999]  [<ffffffff818c7b79>] xen_start_kernel+0x530/0x534
| [    0.000999] ---[ end trace 4eaa2a86a8e2da22 ]---
|

So we need to check if APIC has a proper state.

Reported-by: Ralf Hildebrandt <Ralf.Hildebrandt@charite.de>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
---
 arch/x86/kernel/cpu/perf_event.c |   18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

Index: linux-2.6.git/arch/x86/kernel/cpu/perf_event.c
=====================================================================
--- linux-2.6.git.orig/arch/x86/kernel/cpu/perf_event.c
+++ linux-2.6.git/arch/x86/kernel/cpu/perf_event.c
@@ -627,6 +627,16 @@ static __initconst u64 amd_hw_cache_even
  },
 };
 
+static void __init perfmon_check_apic(struct x86_pmu* pmu)
+{
+	if (cpu_has_apic)
+		return;
+
+	pmu->apic = 0;
+	pr_info("no APIC, boot with the \"lapic\" boot parameter to force-enable it.\n");
+	pr_info("no hardware sampling interrupt available.\n");
+}
+
 /*
  * AMD Performance Monitor K7 and later.
  */
@@ -2062,11 +2072,7 @@ static __init int p6_pmu_init(void)
 
 	x86_pmu = p6_pmu;
 
-	if (!cpu_has_apic) {
-		pr_info("no APIC, boot with the \"lapic\" boot parameter to force-enable it.\n");
-		pr_info("no hardware sampling interrupt available.\n");
-		x86_pmu.apic = 0;
-	}
+	perfmon_check_apic(&x86_pmu);
 
 	return 0;
 }
@@ -2156,6 +2162,8 @@ static __init int amd_pmu_init(void)
 	memcpy(hw_cache_event_ids, amd_hw_cache_event_ids,
 	       sizeof(hw_cache_event_ids));
 
+	perfmon_check_apic(&x86_pmu);
+
 	return 0;
 }
 
--
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