[coreboot] Looking for a volunteer to add Fam15h spectre MSR to coreboot

Arthur Heymans arthur at aheymans.xyz
Wed Apr 11 14:54:46 CEST 2018

Mike Banon <mikebdp2 at gmail.com> writes:

> Line 869 - "const int amd_erratum_319[] =" --- is this code really
> against the Spectre, or its more like against the erratas in general?
> Also, What if someone would like to use either a Linux distro which
> hasnt been upgraded to the latest kernels, or maybe some alternative
> OS like FreeDOS or Kolibri? I think Taiidan has a good point: the
> availability of protection from this vulnerability should not depend
> on your OS and the version of your Linux kernel.

I disagree, the OS and the systems proper operation should depend as
little as possible on the firmware and coreboot generally follows the
philosophy of doing as little as possible. Note that a lot of other
errata get fixed in the kernel as well already. Depending on firmware
for safe operation of outdated or legacy OS seems silly to me...

OTOH there already is some overlap between coreboot and the OS with
stuff like updating microcode which is not always needed...

> Are there any existing MSR writes inside the coreboot code, so that
> they could be copied and modified into the MSR of Taiidan's interest?
> (MSR C001_1029[1]=1) Maybe that MSR write would even be a C code
> 1-liner?
Yes that is quite easy to do, but there is other functionality in that
MSR that is needed for instance when setting up CAR, so care needs to be
taken where this happens. I haven't looked it up but it could also be a
per AP MSR in which case it needs to be programmed on each AP...

Kind regards

Arthur Heymans

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