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Subject[PATCH 4.9 63/93] vfio/spapr: Postpone allocation of userspace version of TCE table
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alexey Kardashevskiy <aik@ozlabs.ru>

[ Upstream commit 39701e56f5f16ea0cf8fc9e8472e645f8de91d23 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/vfio/vfio_iommu_spapr_tce.c | 20 +++++++-------------
1 file changed, 7 insertions(+), 13 deletions(-)

--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -509,6 +509,12 @@ static long tce_iommu_build_v2(struct tc
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,
@@ -582,15 +588,6 @@ static long tce_iommu_create_table(struc
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;
}

@@ -1062,10 +1059,7 @@ static int tce_iommu_take_ownership(stru
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(

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