Re: [Xen-devel] vcpu_info

["pallavi jk" <pallutai@xxxxxxxxx>]

Hi Jeremy,

Yes, I am planning to modify xen and the guest OS as well.

I need to trap every entry into the guest OS from user mode because I need to perform some checks in the hypervisor before transferring control to the guest OS.
So I need to avoid fast handlers which would directly transfer control to the guest OS, as I want to trap this entry first in the hypervisor. I need to do this as I intend to protect applications from a possibly malicious OS, so I want to perform some checks in the hypervisor.

I have just started studying the code. Can you please provide me guidelines about which source files and functions I should concentrate on?

On Fri, Oct 10, 2008 at 10:10 PM, Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:

pallavi jk wrote:

Thanx George.

Yes, am looking into xen-2.0. "struct vcpu_info" is not present there.

Actually am doing a project in which i need to provide a functionality similar to pushing the address of cr2 onto the stack.

Also, how can I avoid the use of fast handlers?...I need to perform some checks inside xen before transferring control to the guest OS for each trap.

Should I modify the "set_trap_table" hypercall for that??

It might help if you give a more complete description of what you're trying to achieve.  The list of things you're trying to do or want don't make a lot of sense on their own.

For example, are you modifying Xen?  Or just guest code?  If you're modifying Xen, it's pretty easy to remove the special case for trap 0x80.

  J

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