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In May 2019, four new microprocessor security flaws, known as "MDS" (Microarchitectural Data Sampling) have been discovered. These flaws affect unpatched Nova Compute nodes and instances running on Intel x86_64 CPUs. The said security flaws are also referred to as "RIDL" (Rogue In-Flight Data Load) and "Fallout". Refer to the following pages for further details: - https://access.redhat.com/security/vulnerabilities/mds - https://mdsattacks.com/ - https://zombieloadattack.com/ * * * If we're adding the guide for "MDS" flaws, then it begs the question: "What about mitigation guides for previous vulnerabilities?" Two points: (a) Write the mitigation document for rest of the previous vulnerabilities too, for completeness' sake. (In April 2018 I wrote this doc[1] for Meltdown — polish it and submit it. Parts of that document's content is already incorporated into the help text for the config attribute `cpu_model_extra_flags`.) (b) For now, we can live with the cliché, "something is better than nothing"; we'll add the other docs "when we get to it". Meanwhile, operators get mitigation details from various other places — processor vendors, Linux distributions, etc. [1] https://kashyapc.fedorapeople.org/Reducing-OpenStack-Guest-Perf-Impact-from-Meltdown.txt Change-Id: I1bb472c3438cc9a91945999d2350b2c59fa6a1f3 Signed-off-by: Kashyap Chamarthy <kchamart@redhat.com>