[Qemu-devel] Support for Nested Paging

[Qemu-devel] Support for Nested Paging

[Ankur Agrawal]

[-- Attachment #1: Type: text/plain, Size: 787 bytes --]

Hi,

I am a student currently working on development of a Hypervisor for JOS Operating System.

I run JOS over QEMU's emulation of x86 architecture. Currently I am planning to add Nested Page Table support to JOS.

Does QEMU emulate the Nested Page Tables implemented by AMD-V architecture or the Intel VT?

Also I am trying to understand the QEMU source with an objective of participating in the Google Summer of Code and contributing to QEMU. I have tried tracing through the code but seems this link http://repo.or.cz/w/qemu/stefanha.git/blob_plain/refs/heads/tracing:/docs/tracing.txt is not updated because many of the options do not work here. I would very happy if someone could provide me links to a good starting point to understand QEMU source code.

Thanks,
Ankur

[-- Attachment #2: Type: text/html, Size: 4570 bytes --]

Re: [Qemu-devel] Support for Nested Paging

[陳韋任]

> Does QEMU emulate the Nested Page Tables implemented by AMD-V architecture or the Intel VT?

  I think the answer is no.
 
> Also I am trying to understand the QEMU source with an objective of participating in the Google Summer of Code and contributing to QEMU. I have tried tracing through the code but seems this link http://repo.or.cz/w/qemu/stefanha.git/blob_plain/refs/heads/tracing:/docs/tracing.txt is not updated because many of the options do not work here. I would very happy if someone could provide me links to a good starting point to understand QEMU source code.

  The "tracing" you mentioned is not tend to help reading the code. Depends on
which part of QEMU you're trying to play with, you have some background
knowledge of it. See "Getting to know the code" on the QEMU wiki [1]. And the
slides mentioned on the mail below is a good start.

  http://www.mail-archive.com/qemu-devel@nongnu.org/msg99864.html

HTH,
chenwj

[1] http://wiki.qemu.org/Documentation/GettingStartedDevelopers#Getting_to_know_the_code

-- 
Wei-Ren Chen (陳韋任)
Computer Systems Lab, Institute of Information Science,
Academia Sinica, Taiwan (R.O.C.)
Tel:886-2-2788-3799 #1667
Homepage: http://people.cs.nctu.edu.tw/~chenwj

Re: [Qemu-devel] Support for Nested Paging

[Stefan Hajnoczi]

On Sun, Mar 04, 2012 at 01:28:04AM +0800, 陳韋任 wrote:
> > Also I am trying to understand the QEMU source with an objective of participating in the Google Summer of Code and contributing to QEMU. I have tried tracing through the code but seems this link http://repo.or.cz/w/qemu/stefanha.git/blob_plain/refs/heads/tracing:/docs/tracing.txt is not updated because many of the options do not work here. I would very happy if someone could provide me links to a good starting point to understand QEMU source code.
> 
>   The "tracing" you mentioned is not tend to help reading the code. Depends on
> which part of QEMU you're trying to play with, you have some background
> knowledge of it.

I think the only thing missing is that you need to use:

  ./configure --enable-trace-backend=<backend>

The docs still say ./configure --trace-backend=<backend>.  I am sending
a pull request that includes a patch to update this.

Stefan

Re: [Qemu-devel] Support for Nested Paging

[Ankur Agrawal]

[-- Attachment #1: Type: text/plain, Size: 2109 bytes --]

Hi,

Thanks for your reply.

I am a graduate student at Stony Brook University and am working on design
and implementation of hypervisors for OSCAR lab (
http://oscar.cs.stonybrook.edu/). Currently I am working on implementing
emulation of Nested Page Tables in QEMU as present in AMD-V architectures.

I would like to know if the QEMU team will be interested in having a patch
which emulates the Nested Page Table and other hardware virtualization
techniques supported by AMD-V or Intel-VT atchitectures.

I would  love to help in maintenance of my patch or any other issues in the
QEMU in future as well.

I would also like to know if there is any chance that this can become a
part of Google Summer of Code 2012.

Thanks,
Ankur

2012/3/3 陳韋任 <chenwj@iis.sinica.edu.tw>

> > Does QEMU emulate the Nested Page Tables implemented by AMD-V
> architecture or the Intel VT?
>
>  I think the answer is no.
>
> > Also I am trying to understand the QEMU source with an objective of
> participating in the Google Summer of Code and contributing to QEMU. I have
> tried tracing through the code but seems this link
> http://repo.or.cz/w/qemu/stefanha.git/blob_plain/refs/heads/tracing:/docs/tracing.txtis not updated because many of the options do not work here. I would very
> happy if someone could provide me links to a good starting point to
> understand QEMU source code.
>
>  The "tracing" you mentioned is not tend to help reading the code. Depends
> on
> which part of QEMU you're trying to play with, you have some background
> knowledge of it. See "Getting to know the code" on the QEMU wiki [1]. And
> the
> slides mentioned on the mail below is a good start.
>
>  http://www.mail-archive.com/qemu-devel@nongnu.org/msg99864.html
>
> HTH,
> chenwj
>
> [1]
> http://wiki.qemu.org/Documentation/GettingStartedDevelopers#Getting_to_know_the_code
>
> --
> Wei-Ren Chen (陳韋任)
> Computer Systems Lab, Institute of Information Science,
> Academia Sinica, Taiwan (R.O.C.)
> Tel:886-2-2788-3799 #1667
> Homepage: http://people.cs.nctu.edu.tw/~chenwj
>

[-- Attachment #2: Type: text/html, Size: 3085 bytes --]

Re: [Qemu-devel] Support for Nested Paging

[Stefan Hajnoczi]

On Sat, Mar 10, 2012 at 04:44:27PM -0500, Ankur Agrawal wrote:
> I am a graduate student at Stony Brook University and am working on design
> and implementation of hypervisors for OSCAR lab (
> http://oscar.cs.stonybrook.edu/). Currently I am working on implementing
> emulation of Nested Page Tables in QEMU as present in AMD-V architectures.
> 
> I would like to know if the QEMU team will be interested in having a patch
> which emulates the Nested Page Table and other hardware virtualization
> techniques supported by AMD-V or Intel-VT atchitectures.
> 
> I would  love to help in maintenance of my patch or any other issues in the
> QEMU in future as well.
> 
> I would also like to know if there is any chance that this can become a
> part of Google Summer of Code 2012.

Yes, you can propose your own project idea.  The key thing is to find a
mentor who is willing to work with you.  You can do that on this mailing
list and #qemu IRC.

I don't know the state of i386 TCG but I suggest checking if there are
prerequisites for vmx/svm that are missing from QEMU.  You may find the
i386 TCG needs some improvements before it becomes possible to work on
vmx/svm itself.  I don't know the answer but you'll need to check this
to see if your project idea is viable.

Stefan