[PATCH 0/2] Misc fixes on registering PCI NVMe CMB

[Icenowy Zheng]

Here is a small patchset that is developed during my investigation of
a WARNING in my boot kernel log (AMD EPYC 7K62 CPU + Intel DC D4502
SSD), which is because of the SSD's too-small CMB block (512KB only).

The first patch is a fix of the PCI DMA registration error handling
codepath, which is just a observation-based patch (because my disk is
only NVMe 1.2 compliant, and the register cleaned up here is only added
in NVMe 1.4).

The second patch really fixes the warning by testing the CMB block
against the memory hotplugging alignment requirement (which the CMB
block of my SSD surely cannot satisfy -- the alignment requirement is
usually 2M with SPAREMEM_VMEMMAP enabled and even larger in other cases).

Refer to commit 6acd7d5ef264 ("libnvdimm/namespace: Enforce
memremap_compat_align()") for a similar approach for NVDIMM subsystem.

Icenowy Zheng (2):
  nvme-pci: clean up CMBMSC when registering CMB fails
  nvme-pci: skip CMB blocks incompatible with PCI P2P DMA

 drivers/nvme/host/pci.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

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2.48.1