Re: [PATCH v4] PCI: Relabel JHL6540 on Lenovo X1 Carbon 7,8

Lukas Wunner
2024-05-15T20:35:24Z

On Wed, May 15, 2024 at 02:53:54PM -0400, Esther Shimanovich wrote:
> On Wed, May 8, 2024 at 1:23???AM Lukas Wunner <lukas@wunner.de> wrote:
> > On Wed, May 01, 2024 at 06:23:28PM -0400, Esther Shimanovich wrote:
> > > On Sat, Apr 27, 2024 at 3:17AM Lukas Wunner <lukas@wunner.de> wrote:
> > > That is correct, when the user-visible issue occurs, no driver is
> > > bound to the NHI and XHCI. The discrete JHL chip is not permitted to
> > > attach to the external-facing root port because of the security
> > > policy, so the NHI and XHCI are not seen by the computer.
> >
> > Could you rework your patch to only rectify the NHI's and XHCI's
> > device properties and leave the bridges untouched?
>
> So I tried a build with that patch, but it never reached the
> tb_pci_fixup function

That means that for some reason, the PCI devices are not associated with
the Thunderbolt ports. Could you add this to the command line:

thunderbolt.dyndbg ignore_loglevel log_buf_len=10M

and this to your kernel config:

CONFIG_DYNAMIC_DEBUG=y

You should see "... is associated with ..." messages in dmesg.
This did work for Mika during his testing with recent Thunderbolt chips.
I amended the patches after his testing but wouldn't expect that to
cause issues.

@Mika, would you mind re-testing if you've got cycles to spare?

> even when NHI and XHCI were both labeled as
> fixed and external facing in the quirk.

Setting the two as fixed and trusted should be sufficient.
The external_facing bit should not be needed on the NHI and XHCI.

> Also, I don't see where you distinguish between an integrated
> Thunderbolt PCIe root port and a root port with no thunderbolt
> functionality built in. Could you point that out to me?

Hm, why would I have to distinguish between the two?

I distinguish between Thunderbolt PCIe Adapters on the root switch
and ones on non-root switches. The latter are attached Device Routers,
the former is the Host Router. I just set the ones on the former to
external_facing, fixed and trusted. Everything downstream is untrusted
and removable.

> I'm not sure how your patch protects against the following case
> scenario I described earlier:
> > Let's say we have a TigerLake CPU, which has integrated
> > Thunderbolt/USB4 capabilities:
> >
> > TigerLake_ThunderboltCPU -> USB-C Port
> > This device also has the ExternalFacingPort property in ACPI and lacks
> > the usb4-host-interface property in the ACPI.
> >
> > My worry is that someone could take an Alpine Ridge Chip Thunderbolt
> > Dock and attach it to the TigerLake CPU
> >
> > TigerLake_ThunderboltCPU -> USB-C Port -> AlpineRidge_Dock
> >
> > If that were to happen, this quirk would incorrectly label the Alpine
> > Ridge Dock as "fixed" instead of "removable".

See above, the Alpine Ridge Dock is never the root switch.
The Tiger Lake CPU is.

Thanks,

Lukas