Fix: Thunderbolt eGPU hot-unplug kernel support

[bdandy]

Thunderbolt eGPU Surprise Removal Support

Prevents kernel crashes when a Thunderbolt eGPU is unplugged unexpectedly.

Changes

Module	Files	Description
nvidia	nv-pci.c, nv.c, nv-acpi.c, nv-i2c.c, nv-rsync.c	Device removal tracking, nvInvalidateDeviceReferences()
nvidia-modeset	nvkms.c, nvkms-kapi.c, nvkms-evo.c, nvkms-dma.c	nvKmsIsDeviceValid() checks, safe event dispatch
nvidia-drm	nvidia-drm-drv.c, nvidia-drm-gem-*.c, nvidia-drm-fb.c	inSurpriseRemoval flag, skip nvKms calls on unplug
nvidia-uvm	uvm_gpu_isr.c, uvm_gpu.c, uvm_pmm_gpu.c, uvm_channel.c, uvm_gpu_semaphore.c	uvm_parent_gpu_is_accessible() guards in ISR, cleanup, and memory paths
RM core	nv_gpu_ops.c, rs_server.c, kernel_gsp.c, intr.c	gpuIsLost checks, graceful session teardown

Key Protections

• ISR handlers: Skip HAL calls when GPU not accessible
• Memory cleanup: Skip PMA/fault buffer operations for removed GPU
• Semaphore reads: Return cached values instead of reading GPU memory
• DRM objects: Skip nvKms free calls during surprise removal
• Session destroy: Warn instead of assert on orphaned devices

Testing

RTX 3060 + Thunderbolt 3: idle unplug, workload unplug, reconnect, module reload

fixes #842

[CLAassistant]

All committers have signed the CLA.

[roger-pmta]

Thanks! Fyi, this appears related to some of the crashes I was seeing on #979 and worked around in #984.

[bdandy]

I think that #984 is not related as it's about wrong detection of external gpu.

PR was tested on Thunderbolt 3 with 3060 GPU and everything working perfectly now (I was waiting for a fix more than few years).

As PR was initially created for 580.105.08 - merged it with master

Please review the changes and apply if possible!

Additionally created AUR package for those who need it right now https://aur.archlinux.org/packages/nvidia-open-egpu-dkms

[roger-pmta]

I think that #984 is not related as it's about wrong detection of external gpu.

Sorry, I should have been more clear: I'm also facing crashes on hot unplug and driver unload as well, mine just happened to be on a TB5 enclosure (which also happened to fail eGPU detection). Will try your patch alongside mine (on #984) when I get a moment and see if resolves crashes on TB5 as well 👍

[Hi-Angel]

I don't think this repository is maintained… I looked through the list of commits and PRs, and it turns out they never merge pull-requests, at least as far back as 2023 there wasn't a single one they merged.