Re: [PATCH v1] iommu/amd: Recognize Hygon southbridge IOAPIC for interrupt remapping

[Pu Wen <pu_wen@foxmail.com>]

On 2026/3/25 19:23, Wei Wang wrote:
> On 3/25/26 6:54 PM, Pu Wen wrote:
>> On 2026/3/25 17:39, Wei Wang wrote:
>>> Hygon systems use the AMD IOMMU driver but newer Hygon platforms report
>>> the southbridge IOAPIC at a different PCI device (00:0b.0), whereas AMD
>>> systems use device 00:14.0.
>> ......
>>> +/* SB IOAPIC device IDs */
>>> +#define IOAPIC_SB_DEVID_AMD    ((0x00 << 8) | PCI_DEVFN(0x14, 0))
>>> +#define IOAPIC_SB_DEVID_HYGON    ((0x00 << 8) | PCI_DEVFN(0x0b, 0))
>> These macro definitions is not accurate, old Hygon processor also use
>> device 0x14, as you mentioned device 0xb is only for 'newer Hygon 
>> platforms'.
>>
> 
> Yes, I noticed that. I mentioned this in the commit log:
> 
> Older Hygon systems still use the original AMD device ID (00:14.0) while
> newer systems use 00:0b.0, so a strict CPU vendor check is insufficient.
> 
> That is also why the code uses the logical OR:
> if (devid == IOAPIC_SB_DEVID_AMD || devid == IOAPIC_SB_DEVID_HYGON)

IMO, if only newer Hygon processor will use device 0xb, the macro should
use a exact name(eg: with a new Hygon family/model), let IOAPIC_SB_DEVID
as the common macro for AMD and Hygon.

-- 
Regards,
Pu Wen