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Re: [Xen-devel] [V10 PATCH 09/23] PVH xen: introduce pvh_set_vcpu_info() and vmx_pvh_set_vcpu_info()

On Tue, 13 Aug 2013 11:49:54 +0100
"Jan Beulich" <JBeulich@xxxxxxxx> wrote:

> >>> On 13.08.13 at 02:27, Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
> >>> wrote:
> > On Mon, 12 Aug 2013 08:54:34 +0100 "Jan Beulich"
> If you think so, then you're not clear of the implications, including
> that this - being part of the hypervisor/guest interface - needs to
> be fixed _now_ rather than later. What I think you neglect here is
> that struct vcpu_guest_context is also used for save/restore, and
> there you _need_ to properly represent the LDT. So you have two
> choices: Keep the structure the way it is and require the guest to
> do LDT management the PV way (which will be very hard, as you
> have no spare selectors to use for it), or do things the HVM way
> (having the guest use the LDT instruction, implying that it's the
> selector and nothing else that needs to be saved/restored).
> If you go that latter, more natural route, then you next need to
> (immediately) decide whether the extra context will also be save/
> restored HVM-like (via struct hvm_hw_cpu), in which case the LDT
> related fields mentioned above are just unused on the PVH case
> (and you'd want to validate that they're zeroed).

I completely intend for save/restore to be the HVM way, that would make
most sense. This brings back to patch version 0, LDT related fields
are unused on PVH :). 


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