On Wed, 2012-12-12 at 16:30 -0700, Alex Williamson wrote: > Locked page accounting in this version is very, very broken. How do > powerpc folks feel about seemingly generic kernel iommu interfaces > messing with the current task mm? Besides that, more problems > below... After a second look & thought... This whole accounting business is fucked. First, we simply can't just randomly return errors from H_PUT_TCE because the process reached some rlimit. This is not a proper failure mode. That means that the guest will probably panic() ... possibly right in the middle of some disk writeback or god knows what. Not good. Also the overhead of doing all that crap on every TCE map/unmap is ridiculous. Finally, it's just not going to work for real mode which we really want, since we can't take the mmap-sem in real mode anyway, so unless we convert that counter to an atomic, we can't do it. I'd suggest just not bothering, or if you want to bother, check once when creating a TCE table that the rlimit is enough to bolt as many pages as can be populated in that table and fail to create *that*. The failure mode is much better, ie, qemu failing to create a PCI bus due to insufficient rlimits. Cheers, Ben. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
