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

[Suthikulpanit, Suravee]

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