PCI: vmd: Handle BUS_RESTRICT_CFG value 3 for Arrow Lake-HX

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On Intel Arrow Lake-HX systems (e.g. Core Ultra 9 275HX on Acer Predator
PH16-73), the VMD controller reports BUS_RESTRICT_CFG = 3 in the VMCONFIG
register. The existing switch statement only handled values 0, 1, and 2,
causing vmd_get_bus_number_start() to return -ENODEV and aborting the
entire VMD probe. This leaves NVMe drives behind the VMD controller
invisible to the kernel.

Hardware registers (VMCAP/VMCONFIG at offsets 0x40/0x44):

  VMD 0000:00:0e.0 (8086:ad0b): VMCAP=0x000f, VMCONFIG=0x03b8
  BUS_RESTRICT_CFG(0x03b8) = (0x03b8 >> 8) & 0x3 = 3

Add cfg=3 as a fallthrough to cfg=2, setting busn_start=224, which is
the correct bus number base for this hardware.

Also add a PCI_POSSIBLE_ERROR() guard after reading VMCONFIG: a failed
config space read returns 0xFFFF, and BUS_RESTRICT_CFG(0xFFFF) = 3,
so without this guard a removed or errored device would falsely match
the new case 3 instead of being caught as an error.

Reported-by: Lin Mohan <linmhwork@outlook.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221137 # Arrow-Lake-S
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221136 # Arrow-Lake-S
Signed-off-by: Ali Alaei <ali.alaei.tabatabaei@gmail.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20260628143450.92492-1-ali.alaei.tabatabaei@gmail.com

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Ali Alaei 2026-06-28 16:34:50 +02:00 • committed by Bjorn Helgaas

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commit 72b32eccbc

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drivers/pci/controller/vmd.c

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