[PATCH v6 13/13] iommu/amd: Add support for nested domain attach/detach

Suravee Suthikulpanit
2026-01-15T06:09:57Z

Introduce set_dte_nested() to program guest translation settings in
the host DTE when attaches the nested domain to a device.

Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
drivers/iommu/amd/nested.c | 73 ++++++++++++++++++++++++++++++++++++++
1 file changed, 73 insertions(+)

diff --git a/drivers/iommu/amd/nested.c b/drivers/iommu/amd/nested.c
index 8154a773eed8..66cc36133c8b 100644
--- a/drivers/iommu/amd/nested.c
+++ b/drivers/iommu/amd/nested.c
@@ -183,6 +183,78 @@ amd_iommu_alloc_domain_nested(struct iommufd_viommu *viommu, u32 flags,
return ERR_PTR(ret);
}

+static void set_dte_nested(struct amd_iommu *iommu, struct iommu_domain *dom,
+ struct iommu_dev_data *dev_data, struct dev_table_entry *new)
+{
+ struct protection_domain *parent;
+ struct nested_domain *ndom = to_ndomain(dom);
+ struct iommu_hwpt_amd_guest *gdte = &ndom->gdte;
+ struct pt_iommu_amdv1_hw_info pt_info;
+
+ /*
+ * The nest parent domain is attached during the call to the
+ * struct iommu_ops.viommu_init(), which will be stored as part
+ * of the struct amd_iommu_viommu.parent.
+ */
+ if (WARN_ON(!ndom->viommu || !ndom->viommu->parent))
+ return;
+
+ parent = ndom->viommu->parent;
+ amd_iommu_make_clear_dte(dev_data, new);
+
+ /* Retrieve the current pagetable info via the IOMMU PT API. */
+ pt_iommu_amdv1_hw_info(&parent->amdv1, &pt_info);
+
+ /*
+ * Use domain ID from nested domain to program DTE.
+ * See amd_iommu_alloc_domain_nested().
+ */
+ amd_iommu_set_dte_v1(dev_data, parent, ndom->gdom_info->hdom_id,
+ &pt_info, new);
+
+ /* GV is required for nested page table */
+ new->data[0] |= DTE_FLAG_GV;
+
+ /* Guest PPR */
+ new->data[0] |= gdte->dte[0] & DTE_FLAG_PPR;
+
+ /* Guest translation stuff */
+ new->data[0] |= gdte->dte[0] & (DTE_GLX | DTE_FLAG_GIOV);
+
+ /* GCR3 table */
+ new->data[0] |= gdte->dte[0] & DTE_GCR3_14_12;
+ new->data[1] |= gdte->dte[1] & (DTE_GCR3_30_15 | DTE_GCR3_51_31);
+
+ /* Guest paging mode */
+ new->data[2] |= gdte->dte[2] & DTE_GPT_LEVEL_MASK;
+}
+
+static int nested_attach_device(struct iommu_domain *dom, struct device *dev,
+ struct iommu_domain *old)
+{
+ struct dev_table_entry new = {0};
+ struct iommu_dev_data *dev_data = dev_iommu_priv_get(dev);
+ struct amd_iommu *iommu = get_amd_iommu_from_dev_data(dev_data);
+ int ret = 0;
+
+ /*
+ * Needs to make sure PASID is not enabled
+ * for this attach path.
+ */
+ if (WARN_ON(dev_data->pasid_enabled))
+ return -EINVAL;
+
+ mutex_lock(&dev_data->mutex);
+
+ set_dte_nested(iommu, dom, dev_data, &new);
+
+ amd_iommu_update_dte(iommu, dev_data, &new);
+
+ mutex_unlock(&dev_data->mutex);
+
+ return ret;
+}
+
static void nested_domain_free(struct iommu_domain *dom)
{
struct guest_domain_mapping_info *curr;
@@ -217,5 +289,6 @@ static void nested_domain_free(struct iommu_domain *dom)
}

static const struct iommu_domain_ops nested_domain_ops = {
+ .attach_dev = nested_attach_device,
.free = nested_domain_free,
};
--
2.34.1