Re: [Xen-devel] [PATCH] VMX: XSA-60 workaround

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.08.13 at 08:21, "Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx> wrote:
> Jan Beulich wrote on 2013-08-20:
>>>>> On 20.08.13 at 09:34, "Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx> wrote:
>>> Yes. Another solution is that to prepare a new EPT table with
>>> setting UC in all entries. When guest set CD, then just change the
>>> EPTP to point to the new table. And back to old EPT table when guest clear 
> it.
>> 
>> Consuming how much extra memory for e.g. a 1Tb guest?
> Memory shouldn't be a problem in such platform. Also, modern CPUs already 
> support the 1G EPT page size.

Wasting memory is always a problem, and 1Gb pages aren't
guaranteed to be available at domain creation time. I view this
dual table approach only as a last resort thing (and if we were to
go this route we ought to evaluate whether this or the non-
sharing approach [EPT/VT-d, with the EPT one having the option
of getting re-populated on demand] are preferable, which among
other things part depends on whether all vCPU-s have to be
running on the same EPT table).

Jan


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