Introduce a new ioctl to allocate a vDEVICE object. Since a vDEVICE object
is a connection of an iommufd_iommufd object and an iommufd_viommu object,
require both as the ioctl inputs and take refcounts in the ioctl handler.

Add to the vIOMMU object a "vdevs" xarray, indexed by a per-vIOMMU virtual
device ID, which can be:
 - Virtual StreamID on a nested ARM SMMUv3, an index to a Stream Table
 - Virtual DeviceID on a nested AMD IOMMU, an index to a Device Table
 - Virtual ID on a nested Intel VT-D IOMMU, an index to a Context Table

Then, let the idev structure hold the allocated vdev pointer with a proper
locking protection.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/iommufd/iommufd_private.h |  12 +++
 include/linux/iommufd.h                 |   2 +
 include/uapi/linux/iommufd.h            |  26 ++++++
 drivers/iommu/iommufd/device.c          |  11 +++
 drivers/iommu/iommufd/main.c            |   7 ++
 drivers/iommu/iommufd/viommu.c          | 108 ++++++++++++++++++++++++
 6 files changed, 166 insertions(+)

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 8c9ab35eaea5..05587c60d0d3 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -391,6 +391,7 @@ struct iommufd_device {
 	struct iommufd_object obj;
 	struct iommufd_ctx *ictx;
 	struct iommufd_group *igroup;
+	struct iommufd_vdevice *vdev;
 	struct list_head group_item;
 	/* always the physical device */
 	struct device *dev;
@@ -505,8 +506,19 @@ static inline int iommufd_hwpt_replace_device(struct iommufd_device *idev,
 	return iommu_group_replace_domain(idev->igroup->group, hwpt->domain);
 }
 
+static inline struct iommufd_viommu *
+iommufd_get_viommu(struct iommufd_ucmd *ucmd, u32 id)
+{
+	return container_of(iommufd_get_object(ucmd->ictx, id,
+					       IOMMUFD_OBJ_VIOMMU),
+			    struct iommufd_viommu, obj);
+}
+
 int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd);
 void iommufd_viommu_destroy(struct iommufd_object *obj);
+int iommufd_vdevice_alloc_ioctl(struct iommufd_ucmd *ucmd);
+void iommufd_vdevice_destroy(struct iommufd_object *obj);
+void iommufd_vdevice_abort(struct iommufd_object *obj);
 
 #ifdef CONFIG_IOMMUFD_TEST
 int iommufd_test(struct iommufd_ucmd *ucmd);
diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index 5d61a1d2947a..821816e3b1fd 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -90,6 +90,8 @@ struct iommufd_viommu {
 
 	const struct iommufd_viommu_ops *ops;
 
+	struct xarray vdevs;
+
 	unsigned int type;
 };
 
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 09c1b4ba46d8..407747785f6a 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -52,6 +52,7 @@ enum {
 	IOMMUFD_CMD_HWPT_INVALIDATE = 0x8d,
 	IOMMUFD_CMD_FAULT_QUEUE_ALLOC = 0x8e,
 	IOMMUFD_CMD_VIOMMU_ALLOC = 0x8f,
+	IOMMUFD_CMD_VDEVICE_ALLOC = 0x90,
 };
 
 /**
@@ -896,4 +897,29 @@ struct iommu_viommu_alloc {
 	__u32 out_viommu_id;
 };
 #define IOMMU_VIOMMU_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VIOMMU_ALLOC)
+
+/**
+ * struct iommu_vdevice_alloc - ioctl(IOMMU_VDEVICE_ALLOC)
+ * @size: sizeof(struct iommu_vdevice_alloc)
+ * @viommu_id: vIOMMU ID to associate with the virtual device
+ * @dev_id: The pyhsical device to allocate a virtual instance on the vIOMMU
+ * @__reserved: Must be 0
+ * @virt_id: Virtual device ID per vIOMMU, e.g. vSID of ARM SMMUv3, vDeviceID
+ *           of AMD IOMMU, and vID of a nested Intel VT-d to a Context Table.
+ * @out_vdevice_id: Output virtual instance ID for the allocated object
+ * @__reserved2: Must be 0
+ *
+ * Allocate a virtual device instance (for a physical device) against a vIOMMU.
+ * This instance holds the device's information (related to its vIOMMU) in a VM.
+ */
+struct iommu_vdevice_alloc {
+	__u32 size;
+	__u32 viommu_id;
+	__u32 dev_id;
+	__u32 __reserved;
+	__aligned_u64 virt_id;
+	__u32 out_vdevice_id;
+	__u32 __reserved2;
+};
+#define IOMMU_VDEVICE_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VDEVICE_ALLOC)
 #endif
diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 5fd3dd420290..e50113305a9c 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -277,6 +277,17 @@ EXPORT_SYMBOL_NS_GPL(iommufd_ctx_has_group, IOMMUFD);
  */
 void iommufd_device_unbind(struct iommufd_device *idev)
 {
+	u32 vdev_id = 0;
+
+	/* idev->vdev object should be destroyed prior, yet just in case.. */
+	mutex_lock(&idev->igroup->lock);
+	if (idev->vdev)
+		vdev_id = idev->vdev->obj.id;
+	mutex_unlock(&idev->igroup->lock);
+	/* Relying on xa_lock against a race with iommufd_destroy() */
+	if (vdev_id)
+		iommufd_object_remove(idev->ictx, NULL, vdev_id, 0);
+
 	iommufd_object_destroy_user(idev->ictx, &idev->obj);
 }
 EXPORT_SYMBOL_NS_GPL(iommufd_device_unbind, IOMMUFD);
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index ab5ee325d809..696ac9e0e74b 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -322,6 +322,7 @@ union ucmd_buffer {
 	struct iommu_option option;
 	struct iommu_vfio_ioas vfio_ioas;
 	struct iommu_viommu_alloc viommu;
+	struct iommu_vdevice_alloc vdev;
 #ifdef CONFIG_IOMMUFD_TEST
 	struct iommu_test_cmd test;
 #endif
@@ -375,6 +376,8 @@ static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
 		 __reserved),
 	IOCTL_OP(IOMMU_VIOMMU_ALLOC, iommufd_viommu_alloc_ioctl,
 		 struct iommu_viommu_alloc, out_viommu_id),
+	IOCTL_OP(IOMMU_VDEVICE_ALLOC, iommufd_vdevice_alloc_ioctl,
+		 struct iommu_vdevice_alloc, __reserved2),
 #ifdef CONFIG_IOMMUFD_TEST
 	IOCTL_OP(IOMMU_TEST_CMD, iommufd_test, struct iommu_test_cmd, last),
 #endif
@@ -513,6 +516,10 @@ static const struct iommufd_object_ops iommufd_object_ops[] = {
 	[IOMMUFD_OBJ_VIOMMU] = {
 		.destroy = iommufd_viommu_destroy,
 	},
+	[IOMMUFD_OBJ_VDEVICE] = {
+		.destroy = iommufd_vdevice_destroy,
+		.abort = iommufd_vdevice_abort,
+	},
 #ifdef CONFIG_IOMMUFD_TEST
 	[IOMMUFD_OBJ_SELFTEST] = {
 		.destroy = iommufd_selftest_destroy,
diff --git a/drivers/iommu/iommufd/viommu.c b/drivers/iommu/iommufd/viommu.c
index e612f3d539b7..77ea41f36b0f 100644
--- a/drivers/iommu/iommufd/viommu.c
+++ b/drivers/iommu/iommufd/viommu.c
@@ -12,6 +12,7 @@ void iommufd_viommu_destroy(struct iommufd_object *obj)
 	if (viommu->ops && viommu->ops->free)
 		viommu->ops->free(viommu);
 	refcount_dec(&viommu->hwpt->common.obj.users);
+	xa_destroy(&viommu->vdevs);
 }
 
 int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd)
@@ -66,6 +67,7 @@ int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd)
 	/* Assume physical IOMMUs are unpluggable (the most likely case) */
 	viommu->iommu_dev = __iommu_get_iommu_dev(idev->dev);
 
+	xa_init(&viommu->vdevs);
 	refcount_inc(&viommu->hwpt->common.obj.users);
 
 	cmd->out_viommu_id = viommu->obj.id;
@@ -83,3 +85,109 @@ int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd)
 	iommufd_put_object(ucmd->ictx, &idev->obj);
 	return rc;
 }
+
+void iommufd_vdevice_abort(struct iommufd_object *obj)
+{
+	struct iommufd_vdevice *old,
+		*vdev = container_of(obj, struct iommufd_vdevice, obj);
+	struct iommufd_viommu *viommu = vdev->viommu;
+	struct iommufd_device *idev = vdev->idev;
+
+	lockdep_assert_held(&idev->igroup->lock);
+
+	if (viommu->ops && viommu->ops->vdevice_free)
+		viommu->ops->vdevice_free(vdev);
+
+	old = xa_cmpxchg(&viommu->vdevs, vdev->id, vdev, NULL, GFP_KERNEL);
+	if (old)
+		WARN_ON(old != vdev);
+
+	refcount_dec(&viommu->obj.users);
+	refcount_dec(&idev->obj.users);
+	idev->vdev = NULL;
+}
+
+void iommufd_vdevice_destroy(struct iommufd_object *obj)
+{
+	struct iommufd_vdevice *vdev =
+		container_of(obj, struct iommufd_vdevice, obj);
+
+	mutex_lock(&vdev->idev->igroup->lock);
+	iommufd_vdevice_abort(obj);
+	mutex_unlock(&vdev->idev->igroup->lock);
+}
+
+int iommufd_vdevice_alloc_ioctl(struct iommufd_ucmd *ucmd)
+{
+	struct iommu_vdevice_alloc *cmd = ucmd->cmd;
+	struct iommufd_vdevice *vdev, *curr;
+	struct iommufd_viommu *viommu;
+	struct iommufd_device *idev;
+	u64 virt_id = cmd->virt_id;
+	int rc = 0;
+
+	if (virt_id > ULONG_MAX)
+		return -EINVAL;
+
+	viommu = iommufd_get_viommu(ucmd, cmd->viommu_id);
+	if (IS_ERR(viommu))
+		return PTR_ERR(viommu);
+
+	idev = iommufd_get_device(ucmd, cmd->dev_id);
+	if (IS_ERR(idev)) {
+		rc = PTR_ERR(idev);
+		goto out_put_viommu;
+	}
+
+	mutex_lock(&idev->igroup->lock);
+	if (idev->vdev) {
+		rc = -EEXIST;
+		goto out_unlock_igroup;
+	}
+
+	if (viommu->ops && viommu->ops->vdevice_alloc)
+		vdev = viommu->ops->vdevice_alloc(viommu, idev->dev, virt_id);
+	else
+		vdev = iommufd_object_alloc(ucmd->ictx, vdev,
+					    IOMMUFD_OBJ_VDEVICE);
+	if (IS_ERR(vdev)) {
+		rc = PTR_ERR(vdev);
+		goto out_unlock_igroup;
+	}
+
+	rc = iommufd_verify_unfinalized_object(ucmd->ictx, &vdev->obj);
+	if (rc) {
+		kfree(vdev);
+		goto out_unlock_igroup;
+	}
+
+	vdev->idev = idev;
+	vdev->id = virt_id;
+	vdev->viommu = viommu;
+
+	idev->vdev = vdev;
+	refcount_inc(&idev->obj.users);
+	refcount_inc(&viommu->obj.users);
+
+	curr = xa_cmpxchg(&viommu->vdevs, virt_id, NULL, vdev, GFP_KERNEL);
+	if (curr) {
+		rc = xa_err(curr) ?: -EBUSY;
+		goto out_abort;
+	}
+
+	cmd->out_vdevice_id = vdev->obj.id;
+	rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
+	if (rc)
+		goto out_abort;
+	iommufd_object_finalize(ucmd->ictx, &vdev->obj);
+	goto out_unlock_igroup;
+
+out_abort:
+	iommufd_object_abort_and_destroy(ucmd->ictx, &vdev->obj);
+out_unlock_igroup:
+	mutex_unlock(&idev->igroup->lock);
+	iommufd_put_object(ucmd->ictx, &idev->obj);
+out_put_viommu:
+	iommufd_put_object(ucmd->ictx, &viommu->obj);
+	return rc;
+}
-- 
2.43.0

On 2024/10/22 8:20, Nicolin Chen wrote:
> Introduce a new ioctl to allocate a vDEVICE object. Since a vDEVICE object
> is a connection of an iommufd_iommufd object and an iommufd_viommu object,

nit:

:s/iommufd_iommufd/iommufd_device/g

or not?

> require both as the ioctl inputs and take refcounts in the ioctl handler.
> 
> Add to the vIOMMU object a "vdevs" xarray, indexed by a per-vIOMMU virtual
> device ID, which can be:
>   - Virtual StreamID on a nested ARM SMMUv3, an index to a Stream Table
>   - Virtual DeviceID on a nested AMD IOMMU, an index to a Device Table
>   - Virtual ID on a nested Intel VT-D IOMMU, an index to a Context Table
> 
> Then, let the idev structure hold the allocated vdev pointer with a proper
> locking protection.
> 
> Signed-off-by: Nicolin Chen<nicolinc@nvidia.com>
> ---
>   drivers/iommu/iommufd/iommufd_private.h |  12 +++
>   include/linux/iommufd.h                 |   2 +
>   include/uapi/linux/iommufd.h            |  26 ++++++
>   drivers/iommu/iommufd/device.c          |  11 +++
>   drivers/iommu/iommufd/main.c            |   7 ++
>   drivers/iommu/iommufd/viommu.c          | 108 ++++++++++++++++++++++++
>   6 files changed, 166 insertions(+)

Thanks,
baolu

On Tue, Oct 22, 2024 at 11:40:11AM +0800, Baolu Lu wrote:
> On 2024/10/22 8:20, Nicolin Chen wrote:
> > Introduce a new ioctl to allocate a vDEVICE object. Since a vDEVICE object
> > is a connection of an iommufd_iommufd object and an iommufd_viommu object,
> 
> nit:
> 
> :s/iommufd_iommufd/iommufd_device/g
> 
> or not?

Right, thanks!

Nicolin