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

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 13.08.11 at 04:17, Jeremy Fitzhardinge <jeremy@xxxxxxxx> 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).

No, Xen doesn't enforce anything on the user page table that it
wouldn't on a kernel one. In fact, it can't even correlate the
respective (kernel,user) pairs.

Jan


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