[SRU][N:linux-bluefield][PATCH v1 0/4] UBUNTU: SAUCE: dma-buf: Add dma_buf_try_get()

[Stav Aviram]

BugLink: https://bugs.launchpad.net/bugs/2126876

SRU Justification:

[IMPACT]
Port non-upstream VFIO P2P patches that were previously backported to linux-bluefield-5.15 (Ubuntu 22.04 Jammy) into linux-bluefield-6.8 (Ubuntu 24.04 Noble), in order to minimize the divergence between the two kernel versions.
These patches enable VFIO P2P support by allowing MMIO regions to be exported through dma-buf, enabling direct memory access between devices such as RDMA and NVMe without CPU involvement.

[FIX]
These are Ubuntu SAUCE patches (not upstream) that were originally backported from kernel 6.0 patch series for linux-bluefield-5.15. The patches include:
1. dma-buf: Add dma_buf_try_get() for safe reference counting
2. vfio: Add vfio_device_get() to increment device references
3. vfio_pci: Consolidate FLR handling to not open code pci_try_reset_function()
4. vfio/pci: Allow MMIO regions to be exported through dma-buf with revocable attachments

[TEST CASE]
Successfully compiled on linux-bluefield-6.8, master-next branch.

[Regression Potential]
Low risk, as the series has already been integrated into Jammy without reported issues.

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2.38.1