iommufd/viommu: Add driver-defined vDEVICE support

NVIDIA VCMDQ driver will have a driver-defined vDEVICE structure and do
some HW configurations with that.

To allow IOMMU drivers to define their own vDEVICE structures, move the
struct iommufd_vdevice to the public header and provide a pair of viommu
ops, similar to get_viommu_size and viommu_init.

Doing this, however, creates a new window between the vDEVICE allocation
and its driver-level initialization, during which an abort could happen
but it can't invoke a driver destroy function from the struct viommu_ops
since the driver structure isn't initialized yet. vIOMMU object doesn't
have this problem, since its destroy op is set via the viommu_ops by the
driver viommu_init function. Thus, vDEVICE should do something similar:
add a destroy function pointer inside the struct iommufd_vdevice instead
of the struct iommufd_viommu_ops.

Note that there is unlikely a use case for a type dependent vDEVICE, so
a static vdevice_size is probably enough for the near term instead of a
get_vdevice_size function op.

Link: https://patch.msgid.link/r/1e751c01da7863c669314d8e27fdb89eabcf5605.1752126748.git.nicolinc@nvidia.com
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Pranjal Shrivastava <praan@google.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 9fdbf5f21f2e6596916b6d7850bd6d856f750d8a..06b8c2e2d9e648c22bd5fe19f44fd4a5b32c396c 100644 (file)
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -653,18 +653,6 @@ 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);
 
-struct iommufd_vdevice {
-       struct iommufd_object obj;
-       struct iommufd_viommu *viommu;
-       struct device *dev;
-
-       /*
-        * Virtual device ID per vIOMMU, e.g. vSID of ARM SMMUv3, vDeviceID of
-        * AMD IOMMU, and vRID of Intel VT-d
-        */
-       u64 virt_id;
-};
-
 #ifdef CONFIG_IOMMUFD_TEST
 int iommufd_test(struct iommufd_ucmd *ucmd);
 void iommufd_selftest_destroy(struct iommufd_object *obj);

diff --git a/drivers/iommu/iommufd/viommu.c b/drivers/iommu/iommufd/viommu.c
index c0365849f84917831152ee9930466301b93aa355..081ee6697a11b04ee5516f98db7fc369ffa22005 100644 (file)
--- a/drivers/iommu/iommufd/viommu.c
+++ b/drivers/iommu/iommufd/viommu.c
@@ -116,6 +116,8 @@ void iommufd_vdevice_destroy(struct iommufd_object *obj)
                container_of(obj, struct iommufd_vdevice, obj);
        struct iommufd_viommu *viommu = vdev->viommu;
 
+       if (vdev->destroy)
+               vdev->destroy(vdev);
        /* xa_cmpxchg is okay to fail if alloc failed xa_cmpxchg previously */
        xa_cmpxchg(&viommu->vdevs, vdev->virt_id, vdev, NULL, GFP_KERNEL);
        refcount_dec(&viommu->obj.users);
@@ -126,6 +128,7 @@ int iommufd_vdevice_alloc_ioctl(struct iommufd_ucmd *ucmd)
 {
        struct iommu_vdevice_alloc *cmd = ucmd->cmd;
        struct iommufd_vdevice *vdev, *curr;
+       size_t vdev_size = sizeof(*vdev);
        struct iommufd_viommu *viommu;
        struct iommufd_device *idev;
        u64 virt_id = cmd->virt_id;
@@ -150,7 +153,22 @@ int iommufd_vdevice_alloc_ioctl(struct iommufd_ucmd *ucmd)
                goto out_put_idev;
        }
 
-       vdev = iommufd_object_alloc_ucmd(ucmd, vdev, IOMMUFD_OBJ_VDEVICE);
+       if (viommu->ops && viommu->ops->vdevice_size) {
+               /*
+                * It is a driver bug for:
+                * - ops->vdevice_size smaller than the core structure size
+                * - not implementing a pairing ops->vdevice_init op
+                */
+               if (WARN_ON_ONCE(viommu->ops->vdevice_size < vdev_size ||
+                                !viommu->ops->vdevice_init)) {
+                       rc = -EOPNOTSUPP;
+                       goto out_put_idev;
+               }
+               vdev_size = viommu->ops->vdevice_size;
+       }
+
+       vdev = (struct iommufd_vdevice *)_iommufd_object_alloc_ucmd(
+               ucmd, vdev_size, IOMMUFD_OBJ_VDEVICE);
        if (IS_ERR(vdev)) {
                rc = PTR_ERR(vdev);
                goto out_put_idev;
@@ -168,6 +186,12 @@ int iommufd_vdevice_alloc_ioctl(struct iommufd_ucmd *ucmd)
                goto out_put_idev;
        }
 
+       if (viommu->ops && viommu->ops->vdevice_init) {
+               rc = viommu->ops->vdevice_init(vdev);
+               if (rc)
+                       goto out_put_idev;
+       }
+
        cmd->out_vdevice_id = vdev->obj.id;
        rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
 

diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index 2d1bf2f97ee311be051de9025a3b4fafabecba8f..bdd10a85eeefae050d8f8411c433d7842ef763ed 100644 (file)
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -104,6 +104,21 @@ struct iommufd_viommu {
        enum iommu_viommu_type type;
 };
 
+struct iommufd_vdevice {
+       struct iommufd_object obj;
+       struct iommufd_viommu *viommu;
+       struct device *dev;
+
+       /*
+        * Virtual device ID per vIOMMU, e.g. vSID of ARM SMMUv3, vDeviceID of
+        * AMD IOMMU, and vRID of Intel VT-d
+        */
+       u64 virt_id;
+
+       /* Clean up all driver-specific parts of an iommufd_vdevice */
+       void (*destroy)(struct iommufd_vdevice *vdev);
+};
+
 /**
  * struct iommufd_viommu_ops - vIOMMU specific operations
  * @destroy: Clean up all driver-specific parts of an iommufd_viommu. The memory
@@ -120,6 +135,14 @@ struct iommufd_viommu {
  *                    array->entry_num to report the number of handled requests.
  *                    The data structure of the array entry must be defined in
  *                    include/uapi/linux/iommufd.h
+ * @vdevice_size: Size of the driver-defined vDEVICE structure per this vIOMMU
+ * @vdevice_init: Initialize the driver-level structure of a vDEVICE object, or
+ *                related HW procedure. @vdev is already initialized by iommufd
+ *                core: vdev->dev and vdev->viommu pointers; vdev->id carries a
+ *                per-vIOMMU virtual ID (refer to struct iommu_vdevice_alloc in
+ *                include/uapi/linux/iommufd.h)
+ *                If driver has a deinit function to revert what vdevice_init op
+ *                does, it should set it to the @vdev->destroy function pointer
  */
 struct iommufd_viommu_ops {
        void (*destroy)(struct iommufd_viommu *viommu);
@@ -128,6 +151,8 @@ struct iommufd_viommu_ops {
                const struct iommu_user_data *user_data);
        int (*cache_invalidate)(struct iommufd_viommu *viommu,
                                struct iommu_user_data_array *array);
+       const size_t vdevice_size;
+       int (*vdevice_init)(struct iommufd_vdevice *vdev);
 };
 
 #if IS_ENABLED(CONFIG_IOMMUFD)
@@ -224,4 +249,10 @@ static inline int iommufd_viommu_report_event(struct iommufd_viommu *viommu,
         BUILD_BUG_ON_ZERO(offsetof(drv_struct, member)) +                     \
         BUILD_BUG_ON_ZERO(!__same_type(struct iommufd_viommu,                 \
                                        ((drv_struct *)NULL)->member)))
+
+#define VDEVICE_STRUCT_SIZE(drv_struct, member)                                \
+       (sizeof(drv_struct) +                                                  \
+        BUILD_BUG_ON_ZERO(offsetof(drv_struct, member)) +                     \
+        BUILD_BUG_ON_ZERO(!__same_type(struct iommufd_vdevice,                \
+                                       ((drv_struct *)NULL)->member)))
 #endif