Re: Apollo Lake with newer microcode: not affected by meltdown anymore?

[Thomas Voegtle]

On Tue, 28 Aug 2018, Thomas Gleixner wrote:

> On Tue, 28 Aug 2018, Thomas Voegtle wrote:
> > Kernel 4.18.5 with old microcode:
> >
> > [    0.000000] microcode: microcode updated early to revision 0x2c, date =
> > 2017-03-25
> > cat /sys/devices/system/cpu/vulnerabilities/meltdown
> > Mitigation: PTI
> >
> >
> > Kernel 4.18.5 with new microcode (microcode-20180807.tgz), same config:
> >
> > [    0.000000] microcode: microcode updated early to revision 0x32, date =
> > 2018-05-11
> > cat /sys/devices/system/cpu/vulnerabilities/meltdown
> > Not affected
> >
> >
> > This happens with 4.14.y and 4.9.y as well.
> >
> > The same with ssb:
> > old microcode: spec_store_bypass:Vulnerable
> > new microcode: spec_store_bypass:Not affected
> >
> > Is this intentional behavior? I have never seen this on other CPUs, such
> > as Gemini Lake or Baytrail, Haswell etc.
>
> Looks like the micro code update has the relevant bits set in the
> IA32_ARCH_CAPABILITIES MSR, which tell the kernel that the CPU is not
> vulnerable. So it seems Intel was able to mitigate the mess in micro code
> for this particular CPU model.

Ah, ok.
Didn't think of the most obvious.
But yes RDCL_NO is set to 1 with the new microcode. Wow.

Thanks and sorry for the noise,

  Thomas