vfio/spapr: Add a helper to create default DMA window

There is already a helper to create a DMA window which does allocate
a table and programs it to the IOMMU group. However
tce_iommu_take_ownership_ddw() did not use it and did these 2 calls
itself to simplify error path.

Since we are going to delay the default window creation till
the default window is accessed/removed or new window is added,
we need a helper to create a default window from all these cases.

This adds tce_iommu_create_default_window(). Since it relies on
a VFIO container to have at least one IOMMU group (for future use),
this changes tce_iommu_attach_group() to add a group to the container
first and then call the new helper.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
index 4efd2b20c35c77590d1dad51ae7c99c23406d614..a67bbfdd86d5b9cbdc110807385440ebe33c4992 100644 (file)
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -710,6 +710,29 @@ static long tce_iommu_remove_window(struct tce_container *container,
        return 0;
 }
 
+static long tce_iommu_create_default_window(struct tce_container *container)
+{
+       long ret;
+       __u64 start_addr = 0;
+       struct tce_iommu_group *tcegrp;
+       struct iommu_table_group *table_group;
+
+       if (!tce_groups_attached(container))
+               return -ENODEV;
+
+       tcegrp = list_first_entry(&container->group_list,
+                       struct tce_iommu_group, next);
+       table_group = iommu_group_get_iommudata(tcegrp->grp);
+       if (!table_group)
+               return -ENODEV;
+
+       ret = tce_iommu_create_window(container, IOMMU_PAGE_SHIFT_4K,
+                       table_group->tce32_size, 1, &start_addr);
+       WARN_ON_ONCE(!ret && start_addr);
+
+       return ret;
+}
+
 static long tce_iommu_ioctl(void *iommu_data,
                                 unsigned int cmd, unsigned long arg)
 {
@@ -1100,9 +1123,6 @@ static void tce_iommu_release_ownership_ddw(struct tce_container *container,
 static long tce_iommu_take_ownership_ddw(struct tce_container *container,
                struct iommu_table_group *table_group)
 {
-       long i, ret = 0;
-       struct iommu_table *tbl = NULL;
-
        if (!table_group->ops->create_table || !table_group->ops->set_window ||
                        !table_group->ops->release_ownership) {
                WARN_ON_ONCE(1);
@@ -1111,47 +1131,7 @@ static long tce_iommu_take_ownership_ddw(struct tce_container *container,
 
        table_group->ops->take_ownership(table_group);
 
-       /*
-        * If it the first group attached, check if there is
-        * a default DMA window and create one if none as
-        * the userspace expects it to exist.
-        */
-       if (!tce_groups_attached(container) && !container->tables[0]) {
-               ret = tce_iommu_create_table(container,
-                               table_group,
-                               0, /* window number */
-                               IOMMU_PAGE_SHIFT_4K,
-                               table_group->tce32_size,
-                               1, /* default levels */
-                               &tbl);
-               if (ret)
-                       goto release_exit;
-               else
-                       container->tables[0] = tbl;
-       }
-
-       /* Set all windows to the new group */
-       for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
-               tbl = container->tables[i];
-
-               if (!tbl)
-                       continue;
-
-               /* Set the default window to a new group */
-               ret = table_group->ops->set_window(table_group, i, tbl);
-               if (ret)
-                       goto release_exit;
-       }
-
        return 0;
-
-release_exit:
-       for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i)
-               table_group->ops->unset_window(table_group, i);
-
-       table_group->ops->release_ownership(table_group);
-
-       return ret;
 }
 
 static int tce_iommu_attach_group(void *iommu_data,
@@ -1161,6 +1141,7 @@ static int tce_iommu_attach_group(void *iommu_data,
        struct tce_container *container = iommu_data;
        struct iommu_table_group *table_group;
        struct tce_iommu_group *tcegrp = NULL;
+       bool create_default_window = false;
 
        mutex_lock(&container->lock);
 
@@ -1203,14 +1184,30 @@ static int tce_iommu_attach_group(void *iommu_data,
        }
 
        if (!table_group->ops || !table_group->ops->take_ownership ||
-                       !table_group->ops->release_ownership)
+                       !table_group->ops->release_ownership) {
                ret = tce_iommu_take_ownership(container, table_group);
-       else
+       } else {
                ret = tce_iommu_take_ownership_ddw(container, table_group);
+               if (!tce_groups_attached(container) && !container->tables[0])
+                       create_default_window = true;
+       }
 
        if (!ret) {
                tcegrp->grp = iommu_group;
                list_add(&tcegrp->next, &container->group_list);
+               /*
+                * If it the first group attached, check if there is
+                * a default DMA window and create one if none as
+                * the userspace expects it to exist.
+                */
+               if (create_default_window) {
+                       ret = tce_iommu_create_default_window(container);
+                       if (ret) {
+                               list_del(&tcegrp->next);
+                               tce_iommu_release_ownership_ddw(container,
+                                               table_group);
+                       }
+               }
        }
 
 unlock_exit: