From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jan Kiszka <jan.kiszka@web.de>
Subject: Re: [PATCH 7/8] KVM: Optimize kvm_read_cr[04]_bits()
Date: Sun, 07 Feb 2010 14:20:22 +0100
Message-ID: <4B6EBE16.1080706@web.de>
References: <1264080712-3981-1-git-send-email-avi@redhat.com> <1264080712-3981-8-git-send-email-avi@redhat.com> <4B6BD63F.1000009@web.de> <4B6EAC88.7000306@redhat.com> <4B6EB32D.3060804@web.de> <4B6EB412.6090704@redhat.com>
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Cc: Marcelo Tosatti <mtosatti@redhat.com>, kvm@vger.kernel.org,
	Gleb Natapov <gleb@redhat.com>
To: Avi Kivity <avi@redhat.com>
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Avi Kivity wrote:
> On 02/07/2010 02:33 PM, Jan Kiszka wrote:
>> Avi Kivity wrote:
>>  =20
>>> On 02/05/2010 10:26 AM, Jan Kiszka wrote:
>>>    =20
>>>> Avi Kivity wrote:
>>>>
>>>>      =20
>>>>> 'mask' is always a constant, so we can check whether it includes a
>>>>> bit that
>>>>> might be owned by the guest very cheaply, and avoid the decache
>>>>> call.  Saves
>>>>> a few hundred bytes of module text.
>>>>>
>>>>>         =20
>>>> -no-kvm-irqchip -smp 2 is broken for my Linux guests since this comm=
it.
>>>> Their user space applications receive #UD and things fall apart.
>>>>
>>>>
>>>>       =20
>>> Does 2c8232fc help?
>>>
>>>     =20
>> Nope, unfortunately.
>>
>>   =20
>=20
> Which specific guests exhibit the behaviour?
>=20

64-bit Linux, various kernels from 2.6.27 to 32. x86-32 appears to be
unaffected.

Jan


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