Patching instructions with PV versions

Patching instructions with PV versions

[Dushyant Bansal]

Hi,
     I understand that in order to improve performance by reducing vm 
exits, kvm uses one shared page between kvm and guest. Now, guest can 
map this page and access its fields using load, store instructions. 
Then, it patches instructions with their paravirtualized versions 
(inside kvm_use_magic_page). I have a few questions.
  Is patching, by default enabled for every guest?
  When is this patching done? Does it target only guest kernel code?

Thanks,
Dushyant

RE: Patching instructions with PV versions

[Sethi Varun-B16395]

Hi Dushyant,
Please refer to the magic page section of the following document:
linux/Documentation/kvm/ppc-pv.txt

Regards
Varun
________________________________________
From: kvm-ppc-owner@vger.kernel.org [kvm-ppc-owner@vger.kernel.org] on behalf of Dushyant Bansal [cs5070214@cse.iitd.ac.in]
Sent: Saturday, February 26, 2011 5:35 PM
To: kvm-ppc@vger.kernel.org
Subject: Patching instructions with PV versions

Hi,
     I understand that in order to improve performance by reducing vm
exits, kvm uses one shared page between kvm and guest. Now, guest can
map this page and access its fields using load, store instructions.
Then, it patches instructions with their paravirtualized versions
(inside kvm_use_magic_page). I have a few questions.
  Is patching, by default enabled for every guest?
  When is this patching done? Does it target only guest kernel code?

Thanks,
Dushyant
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Re: Patching instructions with PV versions

[Dushyant Bansal]

On Monday 28 February 2011 07:43 PM, Sethi Varun-B16395 wrote:
> Hi Dushyant,
> Please refer to the magic page section of the following document:
> linux/Documentation/kvm/ppc-pv.txt
>    
Thanks, now I do have a better understanding.
> Regards
> Varun
> ________________________________________
> From: kvm-ppc-owner@vger.kernel.org [kvm-ppc-owner@vger.kernel.org] on behalf of Dushyant Bansal [cs5070214@cse.iitd.ac.in]
> Sent: Saturday, February 26, 2011 5:35 PM
> To: kvm-ppc@vger.kernel.org
> Subject: Patching instructions with PV versions
>
> Hi,
>       I understand that in order to improve performance by reducing vm
> exits, kvm uses one shared page between kvm and guest. Now, guest can
> map this page and access its fields using load, store instructions.
> Then, it patches instructions with their paravirtualized versions
> (inside kvm_use_magic_page). I have a few questions.
>    Is patching, by default enabled for every guest?
>    When is this patching done? Does it target only guest kernel code?
>
> Thanks,
> Dushyant
> --
> To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in
> the body of a message to majordomo@vger.kernel.org
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>