Re: [Xen-devel] xenoprof passive profiling and "mode" setting

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 5 Jul 2006, at 19:27, Ray Bryant wrote:

> So, how is that possibly true for the kernel in an HVM guest?
> (Wouldn't guest_kernel_mode(regs) be false in that case since it is not
> running ring_3()?)
guest_kernel_mode() does not work for HVM guests. It may need to be 
fixed -- it had previously only been used in paravirtual-only contexts.
It might make sense to invert[*] the predicate and rename to 
user_mode(). Then definition is simply ring_3(regs) for x86/32 and 
(ring_3(regs) && !((v)->arch.flags & TF_kernel_mode)) for x86/64.
> Also, wouldn't ring_0(regs) be true if we are running in kernel mode 
> in an HVM
> guest?    This code appears to assign such a sample to being part of 
> xen,
> right?
ring_0(regs) should be replaced by !guest_mode(regs).

So maybe:
  int mode = 2;
  if (guest_mode(regs))
      mode = user_mode(current, regs) ? 0 : 1;

 -- Keir

[*] Not really inversion, as neither guest_kernel_mode() nor 
user_mode() are true for hypervisor mode.

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