[XEN][PATCH v9 11/19] xen/iommu: Introduce iommu_remove_dt_device()

[Vikram Garhwal <vikram.garhwal@xxxxxxx>]

Remove master device from the IOMMU. This will be helpful when removing the
overlay nodes using dynamic programming during run time.

Signed-off-by: Vikram Garhwal <vikram.garhwal@xxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>

---
Changes from v7:
    Add check if IOMMU is enabled.
    Fix indentation of fail.
---
---
 xen/drivers/passthrough/device_tree.c | 44 +++++++++++++++++++++++++++
 xen/include/xen/iommu.h               |  1 +
 2 files changed, 45 insertions(+)

diff --git a/xen/drivers/passthrough/device_tree.c 
b/xen/drivers/passthrough/device_tree.c
index 096ef2dd68..4cb32dc0b3 100644
--- a/xen/drivers/passthrough/device_tree.c
+++ b/xen/drivers/passthrough/device_tree.c
@@ -128,6 +128,50 @@ int iommu_release_dt_devices(struct domain *d)
     return 0;
 }
 
+int iommu_remove_dt_device(struct dt_device_node *np)
+{
+    const struct iommu_ops *ops = iommu_get_ops();
+    struct device *dev = dt_to_dev(np);
+    int rc;
+
+    if ( !iommu_enabled )
+        return 1;
+
+    if ( !ops )
+        return -EOPNOTSUPP;
+
+    spin_lock(&dtdevs_lock);
+
+    if ( iommu_dt_device_is_assigned_locked(np) )
+    {
+        rc = -EBUSY;
+        goto fail;
+    }
+
+    /*
+     * The driver which supports generic IOMMU DT bindings must have this
+     * callback implemented.
+     */
+    if ( !ops->remove_device )
+    {
+        rc = -EOPNOTSUPP;
+        goto fail;
+    }
+
+    /*
+     * Remove master device from the IOMMU if latter is present and available.
+     * The driver is responsible for removing is_protected flag.
+     */
+    rc = ops->remove_device(0, dev);
+
+    if ( !rc )
+        iommu_fwspec_free(dev);
+
+ fail:
+    spin_unlock(&dtdevs_lock);
+    return rc;
+}
+
 int iommu_add_dt_device(struct dt_device_node *np)
 {
     const struct iommu_ops *ops = iommu_get_ops();
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index 110693c59f..a8e9bc9a2d 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -233,6 +233,7 @@ int iommu_add_dt_device(struct dt_device_node *np);
 
 int iommu_do_dt_domctl(struct xen_domctl *domctl, struct domain *d,
                        XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl);
+int iommu_remove_dt_device(struct dt_device_node *np);
 
 #endif /* HAS_DEVICE_TREE */
 
-- 
2.17.1