Re: [PATCH] x86/cpu, x86/pti: Do not enable PTI on AMD processors

[Pavel Machek]

On Tue 2017-12-26 23:43:54, Tom Lendacky wrote:
> AMD processors are not subject to the types of attacks that the kernel
> page table isolation feature protects against.  The AMD microarchitecture
> does not allow memory references, including speculative references, that
> access higher privileged data when running in a lesser privileged mode
> when that access would result in a page fault.
> 
> Disable page table isolation by default on AMD processors by not setting
> the X86_BUG_CPU_INSECURE feature, which controls whether X86_FEATURE_PTI
> is set.

PTI was originally meant to protect KASLR from memory leaks, before
Spectre was public. I guess that's still valid use on AMD cpus?
								Pavel
								
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