[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] supervisor_mode_kernel and hypercall

  • To: "Yanjun Wu" <yanjun.wu@xxxxxxxxx>
  • From: "Furquan Shaikh" <furquan.m.shaikh@xxxxxxxxx>
  • Date: Mon, 20 Oct 2008 22:10:29 +0530
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
  • Delivery-date: Mon, 20 Oct 2008 09:40:59 -0700
  • Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=fMjBln8Nw4mExUcw3WEp9TnpDQhXppNDvvbuG7Lc/z7ZQEBYEwaOBoVyUp5GT9oip3 utMSuVO5kwojOyrv8OeNy16qGEthMBdoX7XQAgjtX92ECnIdQb4yaWG+2KLg3NUMRy3p QbWdMhDb5E4hb9dIVaj/R+HPcxclOHqYJCCRQ=
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>

Hello all,
Similarly its mentioned in the same book that now fast system call
handlers are used and control does not go to hypervisor.... Does it
mean that there is no interception by the hypervisor at alll during
system call???
You all must be wondering why do i wish to go to a method where system
call would go to guest OS via hypervisor... But actually I am
implementing a security system as a part of my project and i need
this... Can anyone please help me more with it that is it possible in
xen 3.x to make a system call be intercepted by hypervisor before
going to guest kernel? Or do i need to switch to an older xen?

Thanking you all,

On 10/20/08, Yanjun Wu <yanjun.wu@xxxxxxxxx> wrote:
> In xen/arch/x86/x86_32/traps.c, if supervisor_mode_kernel is true, the
> hypercall_page will be initialized by
> hypercall_page_initialise_ring0_kernel.
> my question is, does supervisor_mode_kernel mean that the guest kernel is
> also running in ring0, the same privilege level as Xen hypervisor?
> The book "the definitive guide to the xen hypervisor" (in page 30) says
> hypercall through int82 is now deprecated, and replaced by hypercall_page.
> but int82 can still be found in hypercall_page_initialise_ring1_kernel. In
> what situation it will be used?
> Thanks.
> -Yanjun

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.