powerpc/powernv: Add indirect levels to it_userspace

We want to support sparse memory and therefore huge chunks of DMA windows
do not need to be mapped. If a DMA window big enough to require 2 or more
indirect levels, and a DMA window is used to map all RAM (which is
a default case for 64bit window), we can actually save some memory by
not allocation TCE for regions which we are not going to map anyway.

The hardware tables alreary support indirect levels but we also keep
host-physical-to-userspace translation array which is allocated by
vmalloc() and is a flat array which might use quite some memory.

This converts it_userspace from vmalloc'ed array to a multi level table.

As the format becomes platform dependend, this replaces the direct access
to it_usespace with a iommu_table_ops::useraddrptr hook which returns
a pointer to the userspace copy of a TCE; future extension will return
NULL if the level was not allocated.

This should not change non-KVM handling of TCE tables and it_userspace
will not be allocated for non-KVM tables.

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
index 803ac70ecedf..4bdcf22509e6 100644
--- a/arch/powerpc/include/asm/iommu.h
+++ b/arch/powerpc/include/asm/iommu.h
@@ -69,6 +69,8 @@ struct iommu_table_ops {
 			long index,
 			unsigned long *hpa,
 			enum dma_data_direction *direction);
+
+	__be64 *(*useraddrptr)(struct iommu_table *tbl, long index);
 #endif
 	void (*clear)(struct iommu_table *tbl,
 			long index, long npages);
@@ -123,9 +125,7 @@ struct iommu_table {
 };
 
 #define IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry) \
-		((tbl)->it_userspace ? \
-			&((tbl)->it_userspace[(entry) - (tbl)->it_offset]) : \
-			NULL)
+		((tbl)->it_ops->useraddrptr((tbl), (entry)))
 
 /* Pure 2^n version of get_order */
 static inline __attribute_const__