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

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Message-ID: <20260115060814.10692-14-suravee.suthikulpanit@amd.com>
Date: Thu, 15 Jan 2026 06:08:14 +0000
From: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
To: <jgg@...dia.com>, <nicolinc@...dia.com>
CC: <linux-kernel@...r.kernel.org>, <robin.murphy@....com>, <will@...nel.org>,
	<joro@...tes.org>, <kevin.tian@...el.com>, <jsnitsel@...hat.com>,
	<vasant.hegde@....com>, <iommu@...ts.linux.dev>, <santosh.shukla@....com>,
	<sairaj.arunkodilkar@....com>, <jon.grimm@....com>,
	<prashanthpra@...gle.com>, <wvw@...gle.com>, <wnliu@...gle.com>,
	<gptran@...gle.com>, <kpsingh@...gle.com>, <joao.m.martins@...cle.com>,
	<alejandro.j.jimenez@...cle.com>, Suravee Suthikulpanit
	<suravee.suthikulpanit@....com>
Subject: [PATCH v6 13/13] iommu/amd: Add support for nested domain attach/detach

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@...dia.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....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