I just tested the 4.15 kernel and it is reporting that my old i486 (non-cpuid capable) cpu is vulnerable to all three issues: Meltdown, Spectre V1, and Spectre V2.
I find this to be _unlikely_. /sys/devices/system/cpu/vulnerabilities/* reports the following: meltdown: "Vulnerable" spectre_v1: "Vulnerable" spectre_v2: "Vulnerable: Minimal generic ASM retpoline" The output of dmesg includes: "Spectre V2 mitigation: Vulnerable: Minimal generic ASM retpoline" "Spectre V2 mitigation: Filling RSB on context switch" Also, /proc/cpuinfo reports the following: cpuid level: -1 flags: fpu retpoline rsb_ctxsw bugs: cpu_meltdown spectre_v1 spectre_v2 I have the hardware to test on. Send me your patches. - Matthew Whitehead
