On Sun, 2018-09-23 at 12:33 +1000, Balbir Singh wrote: > > And in so doing, significantly reduces the amount of non-kernel > data > > vulnerable to speculative execution attacks against the kernel. > > (and reduces what data can be loaded into the L1 data cache while > > in kernel mode, to be peeked at by the recent L1 Terminal Fault > > vulnerability). > > I see and there is no way for gadgets to invoke this path from > user space to make their speculation successful? We still have to > flush L1, indepenedent of whether XPFO is enabled or not right? Yes. And even with XPFO and L1 cache flushing enabled, there are more steps that need to be taken to reliably guard against information leaks using speculative execution. Specifically, I'm looking into making certain allocations in the Linux kernel process-local to hide even more memory from prefetching. Another puzzle piece is co-scheduling support that is relevant for systems with enabled hyperthreading: https://lwn.net/Articles/764461/ Julian Amazon Development Center Germany GmbH Berlin - Dresden - Aachen main office: Krausenstr. 38, 10117 Berlin Geschaeftsfuehrer: Dr. Ralf Herbrich, Christian Schlaeger Ust-ID: DE289237879 Eingetragen am Amtsgericht Charlottenburg HRB 149173 B
