Intel disables TSX on older architectures due to security concerns

While browsing the latest Linux kernel patches, Phoronix discovered Intel is disabling Transactional Synchronization Extensions (TSX) for most of its Skylake to Coffee Lake generation processors. Via a microcode update, Intel is turning TSX off by default due to security vulnerabilities. This unexpected change could have profound performance implications for certain workloads. According to Intel, TSX delivers a performance boost of up to 40 percent in some scenarios, and as much as 4-5x higher performance in database transaction benchmarks. For the average consumer, the impact will likely be minimal.

Phoronix writes a memory odering flaw is the reason why Intel is deprecating TSX support.

No widespread announcement on the change seems to have been made as this is the first time I have heard of this deprecation/disabling and not mentioned on other news sites, but noticed it with the fresh round of patches going into the new Linux 5.14 cycle. The Linux kernel is preparing for this microcode change as seen in the flow of new patches this morning for the 5.14 merge window.

Microcode updates are usually delivered via operating system updates, including via Linux kernel updates or Windows Update.