Re: [Xen-devel] arch_set_info_guest() and cr1

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

(old mail, I know)

On Sat, 2011-08-13 at 03:17 +0100, Jeremy Fitzhardinge wrote:
> On 08/12/2011 03:01 PM, Mukesh Rathor wrote:
> > Ah I see it, during save/restore, it is used. 
> > Well, I'm trying to keep the option of using PV paging with hybrid, so 
> > I may need to honor that. But that's phase 2.
> 
> Though it would be nice to re-enable the use of PV writable pagetables
> to get access to HAP, and we could do without that.
> 
> Does Xen require that the user pagetable be a proper subset of the
> kernel pagetable?  If we can assume that and get proper ring protections
> in the HVM container, then we can simply ignore the user pagetable (and
> would have to if we want to get good syscall performance).

IIRC back when I did the (now completely defunct) supervisor mode kernel
stuff that was exactly the assumption which was made and it certainly
worked in practice (although "require" might be a strong term).

Ian.


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel