The NVIDIA SunOS driver supports the retpoline Spectre V2 mitigation technique as identified by: https://software.intel.com/security-software-guidance/api-app/sites/default/files/Retpoline-A-Branch-Target-Injection-Mitigation.pdf

SunOS does not provide a consistent method to determine if the kernel implements Spectre V2 mitigation at driver install time. The NVIDIA SunOS driver implements the non-speculative (safe) version of the retpoline thunk which provides Spectre V2 mitigation for the NVIDIA kernel module. When enabled, users may notice a performance degradation.