Re: [Xen-devel] Hypercall privilege check

["Steven Y. Ko" <sko@xxxxxxxxxxx>]

> Are you doing an OS port by any chance?
No I'm just trying to mess around with privilege levels :)

> The Minix port was done by a Masters student in Ireland.  I think he started
> on Xen 2.0 and I'm not sure he ever moved it over to Xen 3.0 after writing up
> his dissertation.
>
> Code is probably about ... somewhere.  Google knows, I expect ;-)
Thanks for your help. I appreciate it.

- Steve

> Cheers,
> Mark
>
> > - Steve
> >
> > > Cheers,
> > > Mark
> > >
> > > > - Steve
> > > >
> > > > On 6/28/07, Mark Williamson <mark.williamson@xxxxxxxxxxxx> wrote:
> > > > > > I'm wondering where Xen actually checks whether a hypercall is made
> > > > > > from ring 1 or ring 3. Could anyone point me out to the code? Any
> > > > > > pointer would be much appreciated. Thanks!
> > > > >
> > > > > Hypercalls are made from ring 1.  The userspace tools do make
> > > > > hypercalls sometimes, but they do it by calling a special kernel
> > > > > driver, which then does the actual hypercall.  *actually* what that
> > > > > does is to jump into the hypercall transfer page at the right
> > > > > location.  This page contains the actual implementation of the
> > > > > hypercall (using this indirection allows future versions of Xen to
> > > > > supply different implementations of the calls, if appropriate).
> > > > >
> > > > > Take a look at:
> > > > > drivers/xen/privcmd/privcmd.c  in the XenLinux tree.  This is used by
> > > > > the dom0 tools to do control plane operations.
> > > > >
> > > > > Also, take a look at: include/asm-i386/mach-xen/asm/hypercall.h which
> > > > > contains implementations of some other hypercalls.
> > > > >
> > > > > HTH,
> > > > > Cheers,
> > > > > mark
> > > > >
> > > > > --
> > > > > Dave: Just a question. What use is a unicyle with no seat?  And no
> > > > > pedals! Mark: To answer a question with a question: What use is a
> > > > > skateboard? Dave: Skateboards have wheels.
> > > > > Mark: My wheel has a wheel!
> > > >
> > > > _______________________________________________
> > > > Xen-devel mailing list
> > > > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > > > http://lists.xensource.com/xen-devel
> > >
> > > --
> > > Dave: Just a question. What use is a unicyle with no seat?  And no
> > > pedals! Mark: To answer a question with a question: What use is a
> > > skateboard? Dave: Skateboards have wheels.
> > > Mark: My wheel has a wheel!
>
>
>
> --
> Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
> Mark: To answer a question with a question: What use is a skateboard?
> Dave: Skateboards have wheels.
> Mark: My wheel has a wheel!
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