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Intel Details Cascade Lake, Hardware Mitigations for Meltdown, Spectre (extremetech.com)
An anonymous reader shares a report: Ever since Meltdown and Spectre were disclosed, Intel's various customers have been asking how long it would take for hardware fixes to these problems to ship. The fixes will deploy with Cascade Lake, Intel's next server platform due later this year, but the company is finally lifting the lid on some of those improvements and security enhancements at Hot Chips this week.
One major concern? Putting back the performance that previous solutions have lost as a result of Meltdown and Spectre. It's hard to quantify exactly what this looks like, because the impact tends to be extremely workload-dependent. But Intel's guidance has been in the 5-10 percent range, depending on workload and platform, and with the understanding that older CPUs were sometimes hit harder than newer ones. Intel wasn't willing to speak to exactly what kind of uplift users should expect, but Lisa Spelman, VP of Intel's Data Center Group, told AnandTech that the new hardware solutions would have an "impact" on the performance hit from mitigation, and that overall performance would improve at the platform level regardless. Variant 1 will still require software-level protections, while Variant 2 (that's the "classic" Spectre attack) will require a mixture of hardware and software protection. Variant 3 (Meltdown) will be blocked in hardware, 3a (discovered by ARM) patched via firmware, with Variant 5 (Foreshadow) also patched in hardware.
One major concern? Putting back the performance that previous solutions have lost as a result of Meltdown and Spectre. It's hard to quantify exactly what this looks like, because the impact tends to be extremely workload-dependent. But Intel's guidance has been in the 5-10 percent range, depending on workload and platform, and with the understanding that older CPUs were sometimes hit harder than newer ones. Intel wasn't willing to speak to exactly what kind of uplift users should expect, but Lisa Spelman, VP of Intel's Data Center Group, told AnandTech that the new hardware solutions would have an "impact" on the performance hit from mitigation, and that overall performance would improve at the platform level regardless. Variant 1 will still require software-level protections, while Variant 2 (that's the "classic" Spectre attack) will require a mixture of hardware and software protection. Variant 3 (Meltdown) will be blocked in hardware, 3a (discovered by ARM) patched via firmware, with Variant 5 (Foreshadow) also patched in hardware.
This seems like an effort to stick a bunch of fingers in holes in a dam when the dam has a systemic design flaw. What are the chances that other problems will be discovered after tape-out of the new processors?
These bugs are an indictment of the complexity of the speedup techniques Intel has used. With complexity comes extra design expense, reductions in yield, reductions in reliability, and now, security issues that were not very foreseeable.
Adding more complexity in the form of changes to address all these little problems does not give comfort that the syndrome is fixed.
This was serious enough to warrant going back to the drawing board and designing in changes that eliminate this class of problems, not the individual problems that we know of. This is a disappointing effort.