[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] write page table in user mode
>From: Michael A Fetterman >Sent: 2008年2月4日 20:02 > >> > > It's said to be a forward progress issue, that >instruction page of faulting >> > > IP falls into mapped virtual range by same L1 as the >target frame it tries >> > > to update. So the implication is that the unshadow unfortunately >> > > succeeds. >> >> Do you mean that the guest instruction stream is changing >the VM mapping >> of the page under %eip, from user-space? Wow. > >When I first read Kevin's description, I took it to mean that >the same L1 *page* >(not entry) was mapping the current EIP and the target of the >write. If this is >case, then the current code's prefetching of L1 entries on the >same page is >probably interacting with the user-space write heuristic, causing the >shadow->unshadow->shadow livelock, making for a much easier fix. > Yes, same L1 page. Sorry for confusion. It may be some map-cache- like usage within same 4M virtual range including code itself. But I'm not clear about what you mean as a 'much easier' fix. Could you elaborate? Thanks, Kevin _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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