mapping guest domain memory to Dom0

mapping guest domain memory to Dom0

[Adam Thorsen]

Mark Williamson said this regarding the grant_table api (and the fact
that it is not working yet):

>Right now, domains which need to map other domains
>memory are privileged and can map what they like

Is anybody doing this?  If so, what kernel mechanisms are you using?
(I'm sure this question is very easy to answer for a kernel hacker)


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Re: mapping guest domain memory to Dom0

[Mark A. Williamson]

> >Right now, domains which need to map other domains
> >memory are privileged and can map what they like
>
> Is anybody doing this?  If so, what kernel mechanisms are you using?
> (I'm sure this question is very easy to answer for a kernel hacker)

Yes, shared memory is an important part of Xen's architecture.

The userspace xc library and the xcs control switch map another domain's 
memory to put the kernel image, etc into it.  The code for this is in 
tools/libxc/xc_private.c

The blkback.c, netback.c (and usbback.c if you are on unstable) drivers under 
drivers/xen/{blk,net,usb}back/ show how to map another domain's memory from 
kernel space (it's a bit less user friendly than the userspace interface).

HTH,
Mark


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Re: mapping guest domain memory to Dom0

[Adam Thorsen]

I am using the xc_map_foreign_range() function to attempt to map
memory from a guest domain into Domain 0.  I am guessing that the
value named mfn indicates the page in the guest domain that I wish to
start mapping from.

If this assumption is correct,  how do I get a value for mfn?  Say for
instance, that I wanted to map the kernel running in the guest domain?
 How about a specific process?

-Adam Thorsen


On Wed, 2 Feb 2005 15:53:54 +0000, Mark A. Williamson
<mark.williamson@cl.cam.ac.uk> wrote:
> > >Right now, domains which need to map other domains
> > >memory are privileged and can map what they like
> >
> > Is anybody doing this?  If so, what kernel mechanisms are you using?
> > (I'm sure this question is very easy to answer for a kernel hacker)
> 
> Yes, shared memory is an important part of Xen's architecture.
> 
> The userspace xc library and the xcs control switch map another domain's
> memory to put the kernel image, etc into it.  The code for this is in
> tools/libxc/xc_private.c
> 
> The blkback.c, netback.c (and usbback.c if you are on unstable) drivers under
> drivers/xen/{blk,net,usb}back/ show how to map another domain's memory from
> kernel space (it's a bit less user friendly than the userspace interface).
> 
> HTH,
> Mark
>


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