https://bugs.freedesktop.org/show_bug.cgi?id=109366
Bug ID: 109366 Summary: NULL pointer at pcie_capability_read_dword with Radeon SI vfio passthrough Product: DRI Version: unspecified Hardware: x86-64 (AMD64) OS: Linux (All) Status: NEW Severity: normal Priority: medium Component: DRM/AMDgpu Assignee: dri-devel@lists.freedesktop.org Reporter: ryandbair@gmail.com
Created attachment 143131 --> https://bugs.freedesktop.org/attachment.cgi?id=143131&action=edit dmesg output
My guest is seeing the attached bug and call trace during boot. Kernel 4.20.2-200, also an issue on 4.19 series. 4.18 is similar with the older drm_ prefixed version of the function.
https://bugs.freedesktop.org/show_bug.cgi?id=109366
--- Comment #1 from Alex Williamson alex.williamson@redhat.com --- Use a Q35 VM configuration with the assigned GPU downstream of an emulated PCIe root port as a workaround. The driver assumes this configuration, presumably it's the only one that exists on bare metal, and reads from the upstream device without checking that it is actually present.
https://bugs.freedesktop.org/show_bug.cgi?id=109366
Alex Deucher alexdeucher@gmail.com changed:
What |Removed |Added ---------------------------------------------------------------------------- Component|DRM/AMDgpu |DRM/Radeon
https://bugs.freedesktop.org/show_bug.cgi?id=109366
--- Comment #2 from Alex Deucher alexdeucher@gmail.com --- Created attachment 143133 --> https://bugs.freedesktop.org/attachment.cgi?id=143133&action=edit possible fix
Does this patch fix it? dGPUs are always add in cards, so they always plug into an upstream port on bare metal. The driver needs to query the upstream port to determine what pcie gen speeds and lanes are available on the platform so that the driver can properly adjust them at runtime to save power.
https://bugs.freedesktop.org/show_bug.cgi?id=109366
--- Comment #3 from Ryan Bair ryandbair@gmail.com --- Thank you both for the responses.
I can confirm using the Q35 machine type does not see this issue.
I'm rebuilding a kernel today to test the patch and will report back.
https://bugs.freedesktop.org/show_bug.cgi?id=109366
--- Comment #4 from Ryan Bair ryandbair@gmail.com --- I can confirm the attached patch does fix the issue for i440FX.
https://bugs.freedesktop.org/show_bug.cgi?id=109366
Martin Peres martin.peres@free.fr changed:
What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution|--- |MOVED
--- Comment #5 from Martin Peres martin.peres@free.fr --- -- GitLab Migration Automatic Message --
This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity.
You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.freedesktop.org/drm/amd/issues/861.
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