Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [PATCH 3/5] lguest: avoid accidental recycling of pgdir pages | Date | Fri, 27 Mar 2009 11:54:20 +1030 |
| |
On Friday 27 March 2009 10:47:32 Jeremy Fitzhardinge wrote: > Rusty Russell wrote: > > Impact: potential bugfix > > > > In theory, the kernel could reuse the same page as pgdir for a new process > > while the hypervisor keeps it cached. This would have undesirable results. > > > > You can't just do this in tlb flush?
I don't think so. The problem is that lguest tracks 4 toplevels, using random replacement. This cache is indexed by cr3 value.
Lguest assumes it's told about all pte removals or changes, but simple additions get faulted in. If a pgdir page gets reused we'll potentially have stale values from its previous life as a pgdir, no?
Now, I haven't *seen* this happen... Rusty.
| |