[ANNOUNCE] kvm-43 release

[ANNOUNCE] kvm-43 release

[Avi Kivity]

Only one fix, but an important one.  It fixes booting of newer Linux
versions, which experienced disk and keyboard problems without
-no-kvm-irqchip.

As usual, if you have an issue please try with -no-kvm-irqchip and report.

Changes since kvm-42:
- fix ioapic edge-triggered interrupt handling

Notes:
     If you use the modules bundled with kvm-43, you can use any version
of Linux from 2.6.9 upwards.
     If you use the modules bundled with Linux 2.6.20, you need to use
kvm-12.
     If you use the modules bundled with Linux 2.6.21, you need to use
kvm-17.
     Modules from Linux 2.6.22 and up will work with any kvm version from
kvm-22.  Some features may only be available in newer releases.
     For best performance, use Linux 2.6.23-rc2 or later as the host.

http://kvm.qumranet.com



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Re: [ANNOUNCE] kvm-43 release

[Gerd Hoffmann]

Avi Kivity wrote:
> Only one fix, but an important one.  It fixes booting of newer Linux
> versions, which experienced disk and keyboard problems without
> -no-kvm-irqchip.
> 
> As usual, if you have an issue please try with -no-kvm-irqchip and report.

Updated from -41.  Now my libkvm-using-tool's
kvm_callbacks->try_push_interrupts() callback isn't called any more.
Hmm.  Guess due to the lapic/irqchip changes.  Are there any additional
initializations I have to do now?

As there isn't any real pic-like hardware emulated maybe using
try_to_push_interrupts is a bad idea anyway and I should better move the
code (checks state and calls kvm_inject_irq() if needed) to the
pre_kvm_run() callback?

hints anyone?

  Gerd


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Re: [ANNOUNCE] kvm-43 release

[Avi Kivity]

Gerd Hoffmann wrote:
> Avi Kivity wrote:
>   
>> Only one fix, but an important one.  It fixes booting of newer Linux
>> versions, which experienced disk and keyboard problems without
>> -no-kvm-irqchip.
>>
>> As usual, if you have an issue please try with -no-kvm-irqchip and report.
>>     
>
> Updated from -41.  Now my libkvm-using-tool's
> kvm_callbacks->try_push_interrupts() callback isn't called any more.
> Hmm.  Guess due to the lapic/irqchip changes.  Are there any additional
> initializations I have to do now?
>
> As there isn't any real pic-like hardware emulated maybe using
> try_to_push_interrupts is a bad idea anyway and I should better move the
> code (checks state and calls kvm_inject_irq() if needed) to the
> pre_kvm_run() callback?
>
> hints anyone?
>   

You can call kvm_disable_irqchip_creation() to kill in-kernel pic and 
friends.

(the logic is inverted -- the function should be 
kvm_enable_irqchip_creation() so that this problem would not occur)

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


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Re: [ANNOUNCE] kvm-43 release

[Gerd Hoffmann]

Avi Kivity wrote:
> You can call kvm_disable_irqchip_creation() to kill in-kernel pic and
> friends.
> 
> (the logic is inverted -- the function should be
> kvm_enable_irqchip_creation() so that this problem would not occur)

Ok, will try, next question first though as I'm running in trouble much
earlier in -44:  I get suspious page faults.

I *think* it happens because I'm changing guest page tables from outside
(i.e. host application), and the new intel pgtable optimization bits
don't expect that (yes, it is a vt box).

A quick scan of kvmctl.h doesn't show anything which looks like I could
call to tell kvm the guest page tables have been modified.  Hints how to
handle this?

thanks,
  Gerd

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Re: [ANNOUNCE] kvm-43 release

[Avi Kivity]

Gerd Hoffmann wrote:
> Avi Kivity wrote:
>   
>> You can call kvm_disable_irqchip_creation() to kill in-kernel pic and
>> friends.
>>
>> (the logic is inverted -- the function should be
>> kvm_enable_irqchip_creation() so that this problem would not occur)
>>     
>
> Ok, will try, next question first though as I'm running in trouble much
> earlier in -44:  I get suspious page faults.
>
> I *think* it happens because I'm changing guest page tables from outside
> (i.e. host application), and the new intel pgtable optimization bits
> don't expect that (yes, it is a vt box).
>   

Well, the older implementation doesn't expect that either.  You can 
disable the optimization with bypass_guest_pf=0, though.

> A quick scan of kvmctl.h doesn't show anything which looks like I could
> call to tell kvm the guest page tables have been modified.  Hints how to
> handle this?
>
>   

There's a kvm_mmu_zap_all() function, but it isn't exposed.  It's very 
coarse grained, but can be used for experiments.

You could write a new ioctl that tells kvm that some pages were modified 
by the host; that's useful for guests which page out page tables (and 
so, during page in, disk dma could overwrite a page table).


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


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Re: [ANNOUNCE] kvm-43 release

[Gerd Hoffmann]

>> I *think* it happens because I'm changing guest page tables from outside
>> (i.e. host application), and the new intel pgtable optimization bits
>> don't expect that (yes, it is a vt box).
> 
> Well, the older implementation doesn't expect that either.  You can
> disable the optimization with bypass_guest_pf=0, though.

Thanks.  Using bypass_guest_pf=0 and irqchip_disable() brings things
back to -41 level of functionality.

kvm not expecting both guest and host app changing pagetables could
explain other problems I'm seeing though, so maybe i better fix that.
Long term it isn't planned to stay that way anyway, it's just handy for
proof-of-concept because userspace is very easy to hack and debug ...

thanks,
  Gerd



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