Re: 3.2.1 Unable to reset IRR messages on boot

[Suresh Siddha]

On Mon, 2012-03-12 at 09:24 -0400, Josh Boyer wrote:
> On Wed, Feb 01, 2012 at 12:00:30AM -0800, Suresh Siddha wrote:
> > Yes, it was helpful. Something like the appended patch should ignore the
> > bogus io-apic entry all together. As I can't test this, can you or the
> > reporter give the appended patch a try and ack please?
> 
> Hi Suresh,
> 
> Apologies for the delay.  The original reporter had to return the
> machine he was using.  We've since had another report where this
> happened and your patch below does indeed fix the issue.
> 
> I'd suggest pushing this soon.
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=801501
> 

Thanks Josh. Peter/Ingo, please queue the appended patch for -tip.
---
From: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
Subject: x86, ioapic: add register checks for bogus io-apic entries

With the recent changes to clear_IO_APIC_pin() which tries to clear
remoteIRR bit explicitly, some of the users started to see
"Unable to reset IRR for apic .." messages.

Close look shows that these are related to bogus IO-APIC entries which
return's all 1's for their io-apic registers. And the above mentioned error
messages are benign. But kernel should have ignored such io-apic's in the
first place.

Check if register 0, 1, 2 of the listed io-apic are all 1's and ignore
such io-apic.

Reported-by: Ãlvaro Castillo <midgoon@xxxxxxxxx>
Tested-by: Jon Dufresne <jon@xxxxxxxxxxxxxxx>
Signed-off-by: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
---
 arch/x86/kernel/apic/io_apic.c |   26 ++++++++++++++++++++++++++
 1 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index fb07275..953e54d 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -3979,6 +3979,26 @@ static __init int bad_ioapic(unsigned long address)
 	return 0;
 }
 
+static __init int bad_ioapic_regs(int idx)
+{
+	union IO_APIC_reg_00 reg_00;
+	union IO_APIC_reg_01 reg_01;
+	union IO_APIC_reg_02 reg_02;
+
+	reg_00.raw = io_apic_read(idx, 0);
+	reg_01.raw = io_apic_read(idx, 1);
+	reg_02.raw = io_apic_read(idx, 2);
+
+	if (reg_00.raw == -1 && reg_01.raw == -1 && reg_02.raw == -1) {
+		printk(KERN_WARNING
+		       "I/O APIC 0x%x regs return all ones, skipping!\n",
+		       mpc_ioapic_addr(idx));
+		return 1;
+	}
+
+	return 0;
+}
+
 void __init mp_register_ioapic(int id, u32 address, u32 gsi_base)
 {
 	int idx = 0;
@@ -3995,6 +4015,12 @@ void __init mp_register_ioapic(int id, u32 address, u32 gsi_base)
 	ioapics[idx].mp_config.apicaddr = address;
 
 	set_fixmap_nocache(FIX_IO_APIC_BASE_0 + idx, address);
+
+	if (bad_ioapic_regs(idx)) {
+		clear_fixmap(FIX_IO_APIC_BASE_0 + idx);
+		return;
+	}
+
 	ioapics[idx].mp_config.apicid = io_apic_unique_id(id);
 	ioapics[idx].mp_config.apicver = io_apic_get_version(idx);
 


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