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, 0 insertions, 46 deletions

diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
index 8ab124a67311..54ae6c2be1b7 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -211,44 +211,6 @@ static long tce_iommu_register_pages(struct tce_container *container,
 	return 0;
 }
 
-static long tce_iommu_userspace_view_alloc(struct iommu_table *tbl,
-		struct mm_struct *mm)
-{
-	unsigned long cb = _ALIGN_UP(sizeof(tbl->it_userspace[0]) *
-			tbl->it_size, PAGE_SIZE);
-	unsigned long *uas;
-	long ret;
-
-	BUG_ON(tbl->it_userspace);
-
-	ret = try_increment_locked_vm(mm, cb >> PAGE_SHIFT);
-	if (ret)
-		return ret;
-
-	uas = vzalloc(cb);
-	if (!uas) {
-		decrement_locked_vm(mm, cb >> PAGE_SHIFT);
-		return -ENOMEM;
-	}
-	tbl->it_userspace = (__be64 *) uas;
-
-	return 0;
-}
-
-static void tce_iommu_userspace_view_free(struct iommu_table *tbl,
-		struct mm_struct *mm)
-{
-	unsigned long cb = _ALIGN_UP(sizeof(tbl->it_userspace[0]) *
-			tbl->it_size, PAGE_SIZE);
-
-	if (!tbl->it_userspace)
-		return;
-
-	vfree(tbl->it_userspace);
-	tbl->it_userspace = NULL;
-	decrement_locked_vm(mm, cb >> PAGE_SHIFT);
-}
-
 static bool tce_page_is_contained(struct page *page, unsigned page_shift)
 {
 	/*
@@ -599,12 +561,6 @@ 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, container->mm);
-		if (ret)
-			return ret;
-	}
-
 	for (i = 0; i < pages; ++i) {
 		struct mm_iommu_table_group_mem_t *mem = NULL;
 		__be64 *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry + i);
@@ -685,7 +641,6 @@ static void tce_iommu_free_table(struct tce_container *container,
 {
 	unsigned long pages = tbl->it_allocated_size >> PAGE_SHIFT;
 
-	tce_iommu_userspace_view_free(tbl, container->mm);
 	iommu_tce_table_put(tbl);
 	decrement_locked_vm(container->mm, pages);
 }
@@ -1200,7 +1155,6 @@ static void tce_iommu_release_ownership(struct tce_container *container,
 			continue;
 
 		tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
-		tce_iommu_userspace_view_free(tbl, container->mm);
 		if (tbl->it_map)
 			iommu_release_ownership(tbl);