Re: [PATCH] PCI: Avoid bus reset on NVIDIA GB202 and GB203 GPUs

[sashiko-bot@kernel.org]

> NVIDIA GB202 (GeForce RTX 5090, RTX PRO 6000) and GB203 (GeForce RTX
> 5080/5070 Ti/5070) GPUs train their link at x16 at boot, but after a
> Secondary Bus Reset the link comes back at x8 and stays there until the
> next cold boot.
> 
> The GPU's HD Audio function (e.g. 10de:22e9 on GB203) has no reset method,
> so when both functions are assigned to a VM, vfio-pci falls back to a bus
> reset at VM start and again at release, and the GPU then runs at half
> width. Assigning only function 0 avoids the bus reset because the GPU
> itself supports FLR, which is why the problem is usually reported as
> "passing the audio function breaks x16".
> 
> Observed on an RTX 5080 (10de:2c02) behind an AMD Root Port, kernel
> 7.0.14, Proxmox VE host with a Windows 11 Pro guest:
> 
> [ ... ]
> kept x16.
> 
> Link: https://forum.proxmox.com/threads/asus-x870e-pcie-x8-bifurcation-bug-with-rtx-5090-vfio-passthrough.178461/
> 
> Signed-off-by: mark-ship-it <williamwoodstock79@gmail.com>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261018201727.96924-1-williamwoodstock79@gmail.com?part=1