Re: [PATCH RFT RFC] usb: xhci: Kill hosts with HCE or HSE on command timeout

[Desnes Nunes]

Hello Michal,

On Fri, May 22, 2026 at 6:03 AM Michal Pecio <michal.pecio@xxxxxxxxx> wrote:
> If the bug is deterministic it should be fairly easy to nail it down.
> Attached xhci debugfs patch adds a list of almost all memory the xHC
> is allowed to access, including (if I havevn't missed something) all
> mappings it is allowed to access before any slots are enabled.
>
> Please apply, reboot and then:
>
> zip -r before.zip /sys/kernel/debug/usb/xhci/0000:80:14.0
> # trigger crash kexec and the bug
> zip -r after.zip /sys/kernel/debug/usb/xhci/0000:80:14.0
...
> And since the bug may be an out of bounds access by the HW, if you
> don't mind running slightly experimental patch to a critical subsystem,
> please also apply the DMA guard pages patch. I've been using it for a
> few months without issues, but YMMV. It helps determine which mapping
> is accessed OOB.
>
> Note: DMA guard pages may casue USB to stop working before kexec if
> it's a HW bug masked by memory layout, or begin to work after kexec in
> case of some IOMMU subsystem issues.

Please find the requested information in the attachments below.
Kernel was patched with both patches.

Best Regards,

Desnes

Attachment: after.zip
Description: Zip archive

Attachment: before.zip
Description: Zip archive