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Re: amd64: svs



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.
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