Ingo Molnar wrote: > * Avi Kivity <[EMAIL PROTECTED]> wrote: > > >>> rmap_write_protect() has a BUG_ON() if a physical address is not >>> found the the memslot. But this is a possible scenario if a buggy >>> guest OS loads an invalid or corrupted cr3 value. So exit more >>> gracefully. >>> >> I think a better solution is to detect the invalid cr3 in new_cr3(). >> That way the entire chain of error returns is avoided. >> > > i'm wondering what the right semantics would be though. Kill the VM > context? > > on a real CPU an invalid cr3 does nothing explicitly (besides being a > sure way to get a triple fault) - physical memory is always accessible, > non-present physical memory at most generates an #MCE, but is typically > just returning 0xff, right? So perhaps keep a non-mapped page filled > with 0xff and map non-existent RAM to that? But then this 'RAM' needs to > be made non-writable.
That's a good solution. I don't see why it has to be made non-writable -- it has undefined content, and any old value will do. We have (or maybe had) something like that somewhere. > Looks a bit messy. Cleanest would be to kill the > VM context (without injecting any fault into the guest), but that would > then require an error return chain from set_cr3() ... > set_cr3() is fairly close to the top. I'm mostly worried about keeping the innards of the mmu clean. An alternative is to add a flag to the vcpu which would be examined on entry (vcpu->triple_faulted). -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
