Re: [PATCH 4.9 43/92] x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown

[Nick Lowe]

Hi Arjan and Greg,

Sorry if I am not being clear enough.

My point is that there is a check for X86_VENDOR_AMD now in two places.

It is still hardcoded for the auto boot option which I think should
not be there. The patch on that basis looked incomplete to me.

Put another way, there is no effect to the auto option where the
contents of cpu_no_meltdown[] are changed and
cpu_vulnerable_to_meltdown returns differently.

The auto option does not make use of a determination of the
X86_BUG_CPU_MELTDOWN state.

This seems wrong to me. It does not seem correct to me for the auto
option to have this duplication with a check for just X86_VENDOR_AMD.

Regards,

Nick