Re: [Intel-gfx] alderlake crashes (random memory corruption?) with 6.0 i915 / ucode related

[Tvrtko Ursulin]

+ Jani and Ville for the intel_bios.c warn - no idea if that is relevant.

Hi,

On 15/10/2022 15:25, Hans de Goede wrote:
> Hi,
>
> On 10/13/22 22:33, Hans de Goede wrote:
> > Hi All,
> >
> > Yesterday I got a new Lenovo ThinkPad X1 yoga gen 7 laptop, since I plan
> > to make this my new day to day laptop I have copied over the entire
> > rootfs, /home, etc. from my current laptop to avoid having to tweak
> > everything to my liking again.
> >
> > This meant I had an initramfs generated for the other laptop. Which should
> > be fine since both are Intel machines and the old 5.19.y initramfs-es
> > worked fine. But 6.0.0 crashed with what seems like random memory
> > corruption (list integrity checks failing) until I regenerated the initrd ...
> >
> > Comparing the old vs regenerated initrds showed no relevant differences,
> > which made me think this is a CPU ucode issue (which is pre-fixed
> > to the initrd for early microcode loading).
> >
> > After some tests I have the following obeservations with 6.0.0:
> >
> > 1. The least stable is the old initrd (so with the wrong
> > ucode prefixed) this crashes before ever reaching gdm.
> > I believe that this is caused by late microcode loading
> > kicking in in this case (I though that was being removed?)
> > and doing load microcode loading on the i7-1260P with its
> > mix of P + E cores seems to seriously mess things up.
> >
> > 2. Slightly more stable, lasting at least a few minutes
> > before crashing is using dis_ucode_ldr
> >
> > 3. Using nomodeset seems to stabilize things even with
> > the old initrd with the wrong microcode prefixed
> >
> > 4. 5.19, with an old initrd and with normal modesetting
> > enabled works fine, so in a way this is a 6.0.0 regression
> >
> > 5. Using 6.0 with the new initrd with the new microcode
> > seems mostly stable, although sometimes this seems to
> > hang very early during boot, esp. if a previous boot
> > crashed and I have not run this for a long time yet.
> >
> > 6. After crashes it seems to be necessary to powercycle
> > the machine to get things back in working condition.
> >
> >
> > With 6.0 the following WARN triggers:
> > drivers/gpu/drm/i915/display/intel_bios.c:477:
> >
> >          drm_WARN(&i915->drm, min_size == 0,
> >                   "Block %d min_size is zero\n", section_id);
> >
> > Since nomodeset helps this might be quite relevant, in 5.19.13
> > this does not happen, but I'm not sure if 5.19 has this check
> > at all.
> >
> >
> > There is a 2022/10/07 BIOS update which includes a CPU microcode
> > update available from Lenovo, I have not applied this yet in case
> > people want to investigate this further first.
>
> A quick update on this, the microcode being in the initrd or not
> seems to be a bit of a red herring. Yesterday the machine crashed
> twice at boot with 6.0.0 with an initrd which did correctly have
> the alderlake microcode cpio archive prefixed.
>
> Where as with 5.19 it boots correctly everytime. I will try to
> make some time to git bisect this sometime next week. I expect
> this is an i915 issue though since 6.0.0 with nomodeset on
> the cmdline does seem to boot successfully every time.

Maybe try with KASAN to see if it catches something before random list 
corruption starts happening?

Regards,

Tvrtko