Re: [Xen-devel] [PATCH v2 01/30] xen/x86: move setup of the VM86 TSS to the domain builder

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

On Wed, Sep 28, 2016 at 09:35:21AM -0600, Jan Beulich wrote:
> >>> On 27.09.16 at 17:56, <roger.pau@xxxxxxxxxx> wrote:
> > This is also required for PVHv2 guests if they want to use real-mode, and
> > hvmloader is not executed for those kind of guests.
> 
> While the intention is fine, I'm not convinced of consuming yet another
> special page here: Other than the way hvmloader's allocation works,
> here you permanently take away a page from the guest unconditionally
> which (a) is used only on VMX, (b) only on old hardware, and (c) VMX
> code appears to even be able to help itself without this TSS (at the
> price of doing more emulation).

Yes, real mode should also work without this. Given that I don't think we 
expect real-mode to be used for mostly anything but early AP initialization, 
I guess we could just leave PVHv2 guests without the TSS.

Roger.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel