Spectre variants 3a and 4

Post Syndicated from corbet original https://lwn.net/Articles/755114/rss

Intel has, finally, disclosed
two more Spectre variants, called 3a and 4. The first (“rogue system
register read”) allows system-configuration registers to be read
speculatively, while the second (“speculative store bypass”) could enable
speculative reads to data after a store operation has been speculatively
ignored. Some more information on variant 4 can be found in the
Project Zero bug tracker
. The fix is to install microcode updates,
which are not yet available.