[RFC PATCH 1/4] vfio-nvme: add vfio-nvme lm driver infrastructure

[Bjorn Helgaas]

On Sat, Aug 02, 2025 at 07:47:02PM -0700, Chaitanya Kulkarni wrote:
> Add foundational infrastructure for vfio-nvme, enabling support for live
> migration of NVMe devices via the VFIO framework. The following
> components are included:

> +static void nvmevf_pci_aer_reset_done(struct pci_dev *pdev)
> +{
> +	struct nvmevf_pci_core_device *nvmevf_dev = nvmevf_drvdata(pdev);
> +
> +	if (!nvmevf_dev->migrate_cap)
> +		return;
> +
> +	/*
> +	 * As the higher VFIO layers are holding locks across reset and using
> +	 * those same locks with the mm_lock we need to prevent ABBA deadlock
> +	 * with the state_mutex and mm_lock.

Add blank line between paragraphs.

> +	 * In case the state_mutex was taken already we defer the cleanup work
> +	 * to the unlock flow of the other running context.
> +	 */
> +	spin_lock(&nvmevf_dev->reset_lock);
> +	nvmevf_dev->deferred_reset = true;
> +	if (!mutex_trylock(&nvmevf_dev->state_mutex)) {
> +		spin_unlock(&nvmevf_dev->reset_lock);
> +		return;
> +	}
> +	spin_unlock(&nvmevf_dev->reset_lock);
> +	nvmevf_state_mutex_unlock(nvmevf_dev);
> +}