Re: [PATCH v3] PCI: vmd: Handle BUS_RESTRICT_CFG value 3 for Arrow Lake-HX

[sashiko-bot@kernel.org]

> 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.
> 
> Signed-off-by: Ali Alaei <ali.alaei.tabatabaei@gmail.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260628143450.92492-1-ali.alaei.tabatabaei@gmail.com?part=1