Re: [patch V2 5/5] x86/kaiser: Add boottime disable switch

[Dave Hansen]

On 11/26/2017 03:14 PM, Thomas Gleixner wrote:
> --- a/security/Kconfig
> +++ b/security/Kconfig
> @@ -56,7 +56,7 @@ config SECURITY_NETWORK
>  
>  config KAISER
>  	bool "Remove the kernel mapping in user mode"
> -	depends on X86_64 && SMP && !PARAVIRT
> +	depends on X86_64 && SMP && !PARAVIRT && JUMP_LABEL
>  	help
>  	  This feature reduces the number of hardware side channels by
>  	  ensuring that the majority of kernel addresses are not mapped

One of the reasons for doing the runtime-disable was to get rid of the
!PARAVIRT dependency.  I can add a follow-on here that will act as if we
did "nokaiser" whenever Xen is in play so we can remove this dependency.

I just hope Xen is detectable early enough to do the static patching.