Re: [PATCH v2 10/26] iommu/amd: Assign IOMMU Private Address domain to IOMMU

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

On 6/1/2026 7:59 PM, Jason Gunthorpe wrote:
> On Thu, May 28, 2026 at 05:17:22AM +0000, Suravee Suthikulpanit wrote:
>> By setting the domain ID, pagetable mode, and IOMMU v1 page table in the
>> IOMMU Device Table Entry (DTE) indexed using the device ID of the
>> AMD IOMMU.
>>
>> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
>> ---
>>   drivers/iommu/amd/viommu.c | 31 +++++++++++++++++++++++++++++++
>>   1 file changed, 31 insertions(+)
>>
>> diff --git a/drivers/iommu/amd/viommu.c b/drivers/iommu/amd/viommu.c
>> index 63360eef6b0d..14426649074f 100644
>> --- a/drivers/iommu/amd/viommu.c
>> +++ b/drivers/iommu/amd/viommu.c
>> @@ -173,6 +173,35 @@ u64 amd_viommu_get_vfmmio_addr(struct amd_iommu *iommu, u16 gid)
>>   }
>>   EXPORT_SYMBOL(amd_viommu_get_vfmmio_addr);
>>   
>> +/* Set DTE for IOMMU device */
>> +static void set_iommu_dte(struct amd_iommu *iommu)
>> +{
>> +	u64 dte0, dte1;
>> +	u16 devid = iommu->devid;
>> +	struct pt_iommu_amdv1_hw_info pt_info;
>> +	struct protection_domain *pdom = iommu->viommu_pdom;
>> +	struct dev_table_entry *dev_table = get_dev_table(iommu);
>> +
>> +	pt_iommu_amdv1_hw_info(&pdom->amdv1, &pt_info);
>> +
>> +	pr_debug("%s: host_pt_root=%#llx, mode=%#x\n",
>> +		 __func__, pt_info.host_pt_root, pt_info.mode);
>> +
>> +	dte0 = FIELD_PREP(DTE_HOST_TRP, pt_info.host_pt_root >> 12);
>> +	dte0 |= (pt_info.mode & DEV_ENTRY_MODE_MASK) << DEV_ENTRY_MODE_SHIFT;
>> +	dte0 |= DTE_FLAG_IR | DTE_FLAG_IW | DTE_FLAG_V | DTE_FLAG_TV;
>> +
>> +	dte1 = dev_table[devid].data[1];
>> +	dte1 &= ~DTE_DOMID_MASK;
>> +	dte1 |= pdom->id;
> 
> Why is this editing the DTE in place!?
> 
> The special DTE should be entirely deterministic. Call
> amd_iommu_make_clear_dte(), and use amd_iommu_update_dte() to write
> it like every other DTE.
> 
> Jason

I missed this one. I'll fix in v3.
Suravee