Re: [PATCH 18/24] iommu/amd: Introduce helper function for updating device ID mapping table

["Suthikulpanit, Suravee" <suravee.suthikulpanit@amd.com>]

On 8/10/2026 10:17 PM, Vasant Hegde wrote:
> 
> 
> On 7/27/2026 6:59 PM, Suravee Suthikulpanit wrote:
>>  ... 
>> diff --git a/drivers/iommu/amd/viommu.c b/drivers/iommu/amd/viommu.c
>> index 708f2c7496a4..eb3f5217d856 100644
>> --- a/drivers/iommu/amd/viommu.c
>> +++ b/drivers/iommu/amd/viommu.c
>> @@ -29,7 +29,6 @@
>>   /*
>>    * Guest Device ID Mapping Table
>>    */
>> -#define VIOMMU_MAX_GDEVID	0xFFFF
>>   #define VIOMMU_DEVID_MAPPING_BASE	0x1000000000ULL
>>   #define VIOMMU_DEVID_MAPPING_ENTRY_SIZE	(1 << 20)
>>   
>> @@ -40,6 +39,7 @@
>>   #define VIOMMU_DOMID_MAPPING_BASE	0x2000000000ULL
>>   #define VIOMMU_DOMID_MAPPING_ENTRY_SIZE	(1 << 19)
>>   
>> +#define VIOMMU_VFCTRL_GUEST_DID_MAP_CONTROL0_OFFSET	0x00
>>   #define VIOMMU_VFCTRL_GUEST_DID_MAP_CONTROL1_OFFSET	0x08
>>   
>>   LIST_HEAD(viommu_devid_map);
>> @@ -422,6 +422,53 @@ static void __maybe_unused free_private_vm_region(struct amd_iommu *iommu, u64 *
>>   	*entry = NULL;
>>   }
>>   
>> +#define DEVID_ENTRY_GDEVID_MASK		GENMASK_ULL(61, 46)
>> +#define DEVID_ENTRY_HDEVID_MASK		GENMASK_ULL(29, 14)
>> +#define DEVID_ENTRY_WRITE		BIT_ULL(63)
>> +#define DEVID_ENTRY_VALID		BIT_ULL(0)
>> +
>> +/*
>> + * Program the DevID via VFCTRL registers
>> + * This function will be called during VM init via VFIO.
>> + */
>> +void amd_viommu_set_device_mapping(struct amd_iommu *iommu, u16 hDevId,
>> +				   u16 guestId, u16 gDevId)
> 
> Can we avoid CamelCase?
> 

OK.

>> +{
>> +	u64 val;
>> +	u8 __iomem *vfctrl;
>> +
>> +	pr_debug("%s: iommu_devid=%#x, gid=%#x, hDevId=%#x, gDevId=%#x\n",
>> +		__func__, pci_dev_id(iommu->dev), guestId, hDevId, gDevId);
>> +
>> +	val = FIELD_PREP(DEVID_ENTRY_GDEVID_MASK, gDevId) |
>> +	      FIELD_PREP(DEVID_ENTRY_HDEVID_MASK, hDevId) |
>> +	      DEVID_ENTRY_WRITE | DEVID_ENTRY_VALID;
>> +
>> +	vfctrl = VIOMMU_VFCTRL_MMIO_BASE(iommu, guestId);
>> +
>> +	writeq(val, vfctrl + VIOMMU_VFCTRL_GUEST_DID_MAP_CONTROL0_OFFSET);
>> +}
>> +
>> +/*
>> + * Clear the DevID via VFCTRL registers
>> + * This function will be called during VM destroy via VFIO.
>> + */
>> +static void clear_device_mapping(struct amd_iommu *iommu, u16 guestId, u16 gDevId)
>> +{
>> +	u64 val;
>> +	u8 __iomem *vfctrl;
>> +
>> +	/*
>> +	 * Clear the DevID in VFCTRL registers
>> +	 */
>> +	val = FIELD_PREP(DEVID_ENTRY_GDEVID_MASK, gDevId) |
>> +	      FIELD_PREP(DEVID_ENTRY_HDEVID_MASK, 0) |
>> +	      DEVID_ENTRY_WRITE | DEVID_ENTRY_VALID;
> 
> May be just call amd_viommu_set_device_mapping() with appropriate variables/flags?

Ok. I'll update this in V5.

Thanks,
Suravee