[BUG] x86 : i486 reporting to be vulnerable to Meltdown/Spectre_V1/Spectre_V2

[tedheadster]

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