On 1/30/19 1:44 PM, Vlastimil Babka wrote: > Close that sidechannel by always initiating readahead on the cache if we > encounter a cache miss for preadv2(RWF_NOWAIT); with that in place, probing > the pagecache residency itself will actually populate the cache, making the > sidechannel useless. I fear this does not really close the side channel. You can time the preadv2 function and infer which path it took, so you just bring it down to the same as using mmap and timing accesses. If I understood it correctly, this patch just removes the advantages of preadv2 over mmmap+access for the attacker. Cheers, Daniel
