Intel's Mitigation For CVE-2019-14615 Graphics Vulnerability Obliterates Gen7 iGPU Performance

The Gen7 CVE-2019-14615 mitigation testing were done on two distinct systems: one with a Core i7 3770K Ivy Bridge and the other with a Core i7 4790K Haswell. The systems were basically going back and looking through the racks for some Gen7 Intel graphics setups - the intent isn't to compare the performance between the i7-3770K and i7-4790K given the other hardware/software differences but simply providing these mitigation metrics on two distinct systems.

On each system it was tested with the very latest DRM-Next kernel and then again after the DRM-Next source was patched with the two relevant Gen7 mitigation patches ("Add mechanism to submit a context WA on ring submission" and "gen7: Clear all EU/L3 residual contexts"). Those patches apply cleanly against the current DRM-Next but not against Linux 5.4 stable or Linux 5.5 Git, should you be wanting to run your own tests.

Just to be clear, during this mitigation testing only the patches relevant to CVE-2019-14615 are being toggled. The other CPU/GPU mitigations are at their defaults in just looking at this single new disclosure from 14 January.

The open-source ET: Legacy game built off the open-source Enemy Territory classic game can easily run on Ivy Bridge and Haswell graphics, well, used to more easily until yesterday.... The Core i7 4790K performance dropped from 83 to 37 FPS! Or in the case of the Ivy Bridge Core i7 3770K from 46 to 34 FPS! We really weren't expecting yesterday's mitigations to be this dramatic.

With the SuperTuxKart open-source racing game the performance difference was quite dramatic as well. Haswell or at least the high-end Core i7 4790K CPU appears to be impacted much more than the i7-3770K in these tests.