svn commit: r328625 - in head/sys: amd64/amd64 amd64/ia32 amd64/include dev/cpuctl i386/i386 x86/include x86/x86

[Shawn Webb]

On Wed, Jan 31, 2018 at 02:36:27PM +0000, Konstantin Belousov wrote:
> Author: kib
> Date: Wed Jan 31 14:36:27 2018
> New Revision: 328625
> URL: https://svnweb.freebsd.org/changeset/base/328625
> 
> Log:
>   IBRS support, AKA Spectre hardware mitigation.
>   
>   It is coded according to the Intel document 336996-001, reading of the
>   patches posted on lkml, and some additional consultations with Intel.
>   
>   For existing processors, you need a microcode update which adds IBRS
>   CPU features, and to manually enable it by setting the tunable/sysctl
>   hw.ibrs_disable to 0.  Current status can be checked in sysctl
>   hw.ibrs_active.  The mitigation might be inactive if the CPU feature
>   is not patched in, or if CPU reports that IBRS use is not required, by
>   IA32_ARCH_CAP_IBRS_ALL bit.
>   
>   Sponsored by:	The FreeBSD Foundation
>   MFC after:	1 week
>   Differential revision:	https://reviews.freebsd.org/D14029

Hey Kostik,

Thank you very much for your work on this. I'm curious why you disable
IBPB for userland.

Thanks,

-- 
Shawn Webb
Cofounder and Security Engineer
HardenedBSD

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