Call Depth Tracking For Less Costly Retbleed Mitigation Hopes To Land Soon

[phoronix]

Phoronix: Call Depth Tracking For Less Costly Retbleed Mitigation Hopes To Land Soon

Longtime Linux kernel engineer Peter Zijlstra with Intel has sent out his latest "Call Depth Tracking" patches as a mitigiation for Retbleed that aims to be less costly on system performance than the current mitigation approach. With this latest patch series, he indicates he hopes to soon get this code mainlined...

https://www.phoronix.com/news/Call-Depth-Tracking-Hope-Soon

[xcom]

Will this be useful for Ryzen CPUs too?

[hotaru]

Will this be useful for Ryzen CPUs too?

Ryzen already has the "unret" mitigation as default with much lower performance impact than IBRS:

[Svyatko]

Will this be useful for Ryzen CPUs too?

Yes.

Ryzen already has the "unret" mitigation as default with much lower performance impact than IBRS:

It is insufficient: https://www.phoronix.com/news/AMD-Li...eed-STIBP-IBPB

If opting for the more secure Indirect Branch Prediction Barrier "IBPB" mitigation that can mitigate short speculation windows on basic block boundaries too, rather than just the "unret" default, it now turns out a month later Single Thread Indirect Branch Predictors "STIBP" must also be enabled.

[JEBjames]

Michael

Typo

"mitigiation" should be "mitigation"

[Mangix]

I thought these would be fixed in hardware.

[dlq84]

I thought these would be fixed in hardware.

Like an Intel engineer coming home to your house and replacing your old CPU?

[Mangix]

I mean...even newer CPUs have these issues. They have not been fixed in hardware.