Re: amd64: svs

[Dave Huang <khym%azeotrope.org@localhost>]

On Jan 13, 2018, at 22:20, Emmanuel Dreyfus <manu%netbsd.org@localhost> wrote:

John Klos <john%ziaspace.com@localhost> wrote:

FWIW, Intel updated their microcode on 8-Jan-2018:

https://downloadcenter.intel.com/download/27431/

I can't find any documentation which shows what exactly is fixed for each
family of processors.

It does not seems to fix much.

I tried the tests from git repository
http://github.com/IAIK/meltdown.git

This is Linux-centric, but at least, the "secret" case seems to apply on
NetBSD. It reports vulnerability before (cpu0: microcode version 0x58,
platform ID 1) and after (cpu0: microcode version 0x80, platform ID 1)
microcode upgrade.

And I do not have a spectre test case. Anyone has that?

My understanding is that the microcode update doesn't actually *fix* 

anything by itself. What it does is enable an OS to more easily fix 

things.

The kernel would need to check for the new SPEC_CTRL CPUID bit, 

and if present, twiddle with the new speculation control-related MSRs 

at the appropriate times.

-- 

Name: Dave Huang         |  Mammal, mammal / their names are called /

INet: khym%azeotrope.org@localhost |  they raise a paw / the bat, the cat /

Telegram: @DahanC        |  dolphin and dog / koala bear and hog -- TMBG

Dahan: Hani G Y+C 42 Y++ L+++ W- C++ T++ A+ E+ S++ V++ F- Q+++ P+ B+ PA+ PL++