iommufd/viommu: Support get_viommu_size and viommu_init ops

To ease the for-driver iommufd APIs, get_viommu_size and viommu_init ops
are introduced to replace the viommu_init op.

Let the new viommu_init pathway coexist with the old viommu_alloc one.

Since the viommu_alloc op and its pathway will be soon deprecated, try to
minimize the code difference between them by adding a tentative jump tag.

Note that this fails a !viommu->ops case from now on with a WARN_ON_ONCE
since a vIOMMU is expected to support an alloc_domain_nested op for now,
or some sort of a viommu op in the foreseeable future. This WARN_ON_ONCE
can be lifted, if some day there is a use case wanting !viommu->ops.

Link: https://patch.msgid.link/r/35c5fa5926be45bda82f5fc87545cd3180ad4c9c.1749882255.git.nicolinc@nvidia.com
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/iommu/iommufd/viommu.c b/drivers/iommu/iommufd/viommu.c
index 01df2b985f02a037bfcc7004cc48057d39823c8d..27a39f524840cf56308037835fb6f3e7c606f9bb 100644 (file)
--- a/drivers/iommu/iommufd/viommu.c
+++ b/drivers/iommu/iommufd/viommu.c
@@ -21,6 +21,7 @@ int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd)
        struct iommufd_viommu *viommu;
        struct iommufd_device *idev;
        const struct iommu_ops *ops;
+       size_t viommu_size;
        int rc;
 
        if (cmd->flags || cmd->type == IOMMU_VIOMMU_TYPE_DEFAULT)
@@ -31,11 +32,29 @@ int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd)
                return PTR_ERR(idev);
 
        ops = dev_iommu_ops(idev->dev);
-       if (!ops->viommu_alloc) {
+       if (!ops->get_viommu_size || !ops->viommu_init) {
+               if (ops->viommu_alloc)
+                       goto get_hwpt_paging;
+               rc = -EOPNOTSUPP;
+               goto out_put_idev;
+       }
+
+       viommu_size = ops->get_viommu_size(idev->dev, cmd->type);
+       if (!viommu_size) {
+               rc = -EOPNOTSUPP;
+               goto out_put_idev;
+       }
+
+       /*
+        * It is a driver bug for providing a viommu_size smaller than the core
+        * vIOMMU structure size
+        */
+       if (WARN_ON_ONCE(viommu_size < sizeof(*viommu))) {
                rc = -EOPNOTSUPP;
                goto out_put_idev;
        }
 
+get_hwpt_paging:
        hwpt_paging = iommufd_get_hwpt_paging(ucmd, cmd->hwpt_id);
        if (IS_ERR(hwpt_paging)) {
                rc = PTR_ERR(hwpt_paging);
@@ -47,8 +66,13 @@ int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd)
                goto out_put_hwpt;
        }
 
-       viommu = ops->viommu_alloc(idev->dev, hwpt_paging->common.domain,
-                                  ucmd->ictx, cmd->type);
+       if (ops->viommu_alloc)
+               viommu = ops->viommu_alloc(idev->dev,
+                                          hwpt_paging->common.domain,
+                                          ucmd->ictx, cmd->type);
+       else
+               viommu = (struct iommufd_viommu *)_iommufd_object_alloc(
+                       ucmd->ictx, viommu_size, IOMMUFD_OBJ_VIOMMU);
        if (IS_ERR(viommu)) {
                rc = PTR_ERR(viommu);
                goto out_put_hwpt;
@@ -68,6 +92,18 @@ int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd)
         */
        viommu->iommu_dev = __iommu_get_iommu_dev(idev->dev);
 
+       if (!ops->viommu_alloc) {
+               rc = ops->viommu_init(viommu, hwpt_paging->common.domain);
+               if (rc)
+                       goto out_abort;
+       }
+
+       /* It is a driver bug that viommu->ops isn't filled */
+       if (WARN_ON_ONCE(!viommu->ops)) {
+               rc = -EOPNOTSUPP;
+               goto out_abort;
+       }
+
        cmd->out_viommu_id = viommu->obj.id;
        rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
        if (rc)