On Wed, 15 Dec 2010 00:00:08 +0100 Alexander Graf <agraf@xxxxxxx> wrote: > > On 14.12.2010, at 21:04, Scott Wood wrote: > > > Well, the TLB path might not be so bad if it can reuse an existing > > check for mapping the magic page in the first place -- but if an > > interrupt happens immediately after setting critical, but before saving > > scratch registers, the critical end will not be the next magic page > > write. So you'd still have to either single-step or emulate the stores > > at least. > > We could also move the critical value to its own page, so we only have to trap that one :). Stable ABI... > > Or I suppose we could document that all magic page stores other than > > ending critical must come before checking int_pending, though that seems > > a bit ugly. > > That one's very hard to do with live binary patching Sorry, I was only talking about stores within a critical section -- not unrelated stores that other patched instructions might do. So that once KVM has an interrupt to deliver, and sees that critical is engaged, it knows that the next magic page store will resolve things. Either it is a store to critical, and KVM can now deliver the interrupt -- or it is some other store (scratch or MSR itself) and thus int_pending has not yet been checked. I don't think it would be a problem for live patching. It just seems a bit icky. -Scott -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
