vfio/spapr: Postpone allocation of userspace version of TCE table

The iommu_table struct manages a hardware TCE table and a vmalloc'd
table with corresponding userspace addresses. Both are allocated when
the default DMA window is created and this happens when the very first
group is attached to a container.

As we are going to allow the userspace to configure container in one
memory context and pas container fd to another, we have to postpones
such allocations till a container fd is passed to the destination
user process so we would account locked memory limit against the actual
container user constrainsts.

This postpones the it_userspace array allocation till it is used first
time for mapping. The unmapping patch already checks if the array is
allocated.

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 d0c38b2..4efd2b2 100644 (file)
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -515,6 +515,12 @@ static long tce_iommu_build_v2(struct tce_container *container,
        unsigned long hpa;
        enum dma_data_direction dirtmp;
 
+       if (!tbl->it_userspace) {
+               ret = tce_iommu_userspace_view_alloc(tbl);
+               if (ret)
+                       return ret;
+       }
+
        for (i = 0; i < pages; ++i) {
                struct mm_iommu_table_group_mem_t *mem = NULL;
                unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl,
@@ -588,15 +594,6 @@ static long tce_iommu_create_table(struct tce_container *container,
        WARN_ON(!ret && !(*ptbl)->it_ops->free);
        WARN_ON(!ret && ((*ptbl)->it_allocated_size != table_size));
 
-       if (!ret && container->v2) {
-               ret = tce_iommu_userspace_view_alloc(*ptbl);
-               if (ret)
-                       (*ptbl)->it_ops->free(*ptbl);
-       }
-
-       if (ret)
-               decrement_locked_vm(table_size >> PAGE_SHIFT);
-
        return ret;
 }
 
@@ -1068,10 +1065,7 @@ static int tce_iommu_take_ownership(struct tce_container *container,
                if (!tbl || !tbl->it_map)
                        continue;
 
-               rc = tce_iommu_userspace_view_alloc(tbl);
-               if (!rc)
-                       rc = iommu_take_ownership(tbl);
-
+               rc = iommu_take_ownership(tbl);
                if (rc) {
                        for (j = 0; j < i; ++j)
                                iommu_release_ownership(