PATCH vmx.c: add printk_ratelimit in vmx_intr_assist

PATCH vmx.c: add printk_ratelimit in vmx_intr_assist

[Ryan Harper]

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Add printk_ratelimit check in front of printk.  This prevents spamming
of the message during 32-bit ubuntu 6.06server install.  Previously, it
would hang during the partition formatting stage.

-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253
ryanh-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org

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For some guests (ubuntu6.06-server) on intel machines, vmx_inter_assist spams
a message preventing the guest from making forward progress.  Adding in a
ratelimit check prevents the spamming.

Signed-off-by: Ryan Harper <ryanh-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 548e3a5..1c1ad7f 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -2261,7 +2261,8 @@ static void vmx_intr_assist(struct kvm_vcpu *vcpu)
 	if (intr_info_field & INTR_INFO_VALID_MASK) {
 		if (idtv_info_field & INTR_INFO_VALID_MASK) {
 			/* TODO: fault when IDT_Vectoring */
-			printk(KERN_ERR "Fault when IDT_Vectoring\n");
+			if (printk_ratelimit())
+				printk(KERN_ERR "Fault when IDT_Vectoring\n");
 		}
 		if (has_ext_irq)
 			enable_irq_window(vcpu);

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Re: PATCH vmx.c: add printk_ratelimit in vmx_intr_assist

[Avi Kivity]

Ryan Harper wrote:
> Add printk_ratelimit check in front of printk.  This prevents spamming
> of the message during 32-bit ubuntu 6.06server install.  Previously, it
> would hang during the partition formatting stage.
>   

Applied, but this is worrying.  Do you know whether this is a regression?

-- 
Any sufficiently difficult bug is indistinguishable from a feature.


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Re: PATCH vmx.c: add printk_ratelimit in vmx_intr_assist

[Ryan Harper]

* Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> [2007-12-14 08:49]:
> Ryan Harper wrote:
> >Add printk_ratelimit check in front of printk.  This prevents spamming
> >of the message during 32-bit ubuntu 6.06server install.  Previously, it
> >would hang during the partition formatting stage.
> >  
> 
> Applied, but this is worrying.  Do you know whether this is a regression?

I'll try out older releases to see if we did regress.


-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253
ryanh-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org

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Re: PATCH vmx.c: add printk_ratelimit in vmx_intr_assist

[Ryan Harper]

* Ryan Harper <ryanh-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org> [2007-12-14 09:36]:
> * Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> [2007-12-14 08:49]:
> > Ryan Harper wrote:
> > >Add printk_ratelimit check in front of printk.  This prevents spamming
> > >of the message during 32-bit ubuntu 6.06server install.  Previously, it
> > >would hang during the partition formatting stage.
> > >  
> > 
> > Applied, but this is worrying.  Do you know whether this is a regression?
> 
> I'll try out older releases to see if we did regress.

Looks like kvm-47 introduced the hang during format, -46 finishes the
format just fine and with no printk spamming.  I'll start seeing
if I can bisect down to a particular changeset.

-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253
ryanh-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org

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Re: PATCH vmx.c: add printk_ratelimit in vmx_intr_assist

[Ryan Harper]

* Ryan Harper <ryanh-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org> [2007-12-14 16:14]:
> * Ryan Harper <ryanh-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org> [2007-12-14 09:36]:
> > * Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> [2007-12-14 08:49]:
> > > Ryan Harper wrote:
> > > >Add printk_ratelimit check in front of printk.  This prevents spamming
> > > >of the message during 32-bit ubuntu 6.06server install.  Previously, it
> > > >would hang during the partition formatting stage.
> > > >  
> > > 
> > > Applied, but this is worrying.  Do you know whether this is a regression?
> > 
> > I'll try out older releases to see if we did regress.
> 
> Looks like kvm-47 introduced the hang during format, -46 finishes the
> format just fine and with no printk spamming.  I'll start seeing
> if I can bisect down to a particular changeset.

My git skills are poor and I can't for the life of my figure out how to
get kvm and kvm-userspace checked out at kvm-46 and build them together.
So, instead I tested the nightly tarballs between Oct 10 (kvm-46
release) and Oct 18 (kvm-47).

kvm-snapshot-20071014.tar.gz is the last known good version.
version:        kvm-snapshot-20071014
srcversion:     5F6E5524AD0A76F65C4CF60

The flooding of: [2592349.069880] Fault when IDT_Vectoring starts with
1015 but 1015 can complete the formatting.  16 and 17 won't compile.  18
of course fails completely.

So, something between 14 and 15 added the flooding, and something
between 15 and 18 prevents formatting from progressing.

-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253
ryanh-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org

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Re: PATCH vmx.c: add printk_ratelimit in vmx_intr_assist

[Avi Kivity]

Ryan Harper wrote:
> * Ryan Harper <ryanh-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org> [2007-12-14 09:36]:
>   
>> * Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> [2007-12-14 08:49]:
>>     
>>> Ryan Harper wrote:
>>>       
>>>> Add printk_ratelimit check in front of printk.  This prevents spamming
>>>> of the message during 32-bit ubuntu 6.06server install.  Previously, it
>>>> would hang during the partition formatting stage.
>>>>  
>>>>         
>>> Applied, but this is worrying.  Do you know whether this is a regression?
>>>       
>> I'll try out older releases to see if we did regress.
>>     
>
> Looks like kvm-47 introduced the hang during format, -46 finishes the
> format just fine and with no printk spamming.  I'll start seeing
> if I can bisect down to a particular changeset.
>
>   
Unfortunately there was a window where interrupts were injected outside 
the critical section, causing these errors.  This was introduced in 
kvm-47, so this doesn't help much.


-- 
error compiling committee.c: too many arguments to function


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