Re: [PATCH 00/31 v2] PTI support for x86_32

[Andy Lutomirski]

On Fri, Feb 9, 2018 at 9:25 AM, Joerg Roedel <joro@xxxxxxxxxx> wrote:
> Hi,
>
> here is the second version of my PTI implementation for
> x86_32, based on tip/x86-pti-for-linus. It took a lot longer
> than I had hoped, but there have been a number of obstacles
> on the way. It also isn't the small patch-set anymore that v1
> was, but compared to it this one actually works :)

One thing worth noting is that performance of this whole series is
going to be abysmal due to the complete lack of 32-bit PCID.  Maybe
any kernel built with this option set that runs on a CPU that has the
PCID bit set in CPUID should print a big fat warning like "WARNING:
you are using 32-bit PTI on a 64-bit PCID-capable CPU.  Your
performance will increase dramatically if you switch to a 64-bit
kernel."