[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] [PATCH 1/9] Add cpu idle pwr mgmt to xen
>From: Jan Beulich [mailto:jbeulich@xxxxxxxxxx] >Sent: 2008年4月30日 17:35 > >>>> "Tian, Kevin" <kevin.tian@xxxxxxxxx> 30.04.08 11:12 >>> >>One thing kicking me just now is, whether Linux address check >>style can be used here by temporarily increasing address limit >>in compat logic to bypass relative check in common code? I >>didn't see obvious benefit to reserve a guest virtual addr range >>and let each component to manage internal allocation themselves. >>Linux style seems simpler and compat logic can just use xmalloc >>to create native copy to reduce xlat complexity. > >I intentionally did not go that route when I first wrote these >translation >routines. For one, you wouldn't be able to partly copy things (as I >suggested as an improvement here), since the validity checks would >apply to all or nothing during an individual hypercall (and a >bad 64-bit >field representing a pointer might then slip through). Secondly, the What do you mean by partly copying things? For a 32-on-64 guest, all pointers from guest are 32-bit and compat_handler_okay already ensures compat pointers validity. Only native structure may have 64-bit pointer field, which is checked by common guest_handle_okay if from a 64bit guest, or is trusted by increasing addr limitation if from compat layer... >static pre-allocation used currently also avoids spurious failures of >hypercalls (there may be deterministic failures if the combined set >of indirect hypercall arguments exceeds the pre-allocation size. That's also the limitation of current approach by pre-defined size, which is not scalable if 2nd level pointer are variable decided by some count field. Thanks, Kevin _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
|
![]() |
Lists.xenproject.org is hosted with RackSpace, monitoring our |