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powerpc/iommu: Allocate it_map by vmalloc 

The IOMMU table uses the it_map bitmap to keep track of allocated DMA
pages. This has always been a contiguous array allocated at either
the boot time or when a passed through device is returned to the host OS.
The it_map memory is allocated by alloc_pages() which allocates
contiguous physical memory.

Such allocation method occasionally creates a problem when there is
no big chunk of memory available (no free memory or too fragmented).
On powernv/ioda2 the default DMA window requires 16MB for it_map.

This replaces alloc_pages_node() with vzalloc_node() which allocates
contiguous block but in virtual memory. This should reduce changes of
failure but should not cause other behavioral changes as it_map is only
used by the kernel's DMA hooks/api when MMU is on.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210216033307.69863-2-aik@ozlabs.ru
This commit is contained in:
Alexey Kardashevskiy 2021-02-16 14:33:06 +11:00 committed by Michael Ellerman
parent 0db1146167
commit 7f1fa82d79
1 changed files with 3 additions and 12 deletions
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15
arch/powerpc/kernel/iommu.c
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@ -718,7 +718,6 @@ struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid,
{
unsigned long sz;
static int welcomed = 0;
struct page *page;
unsigned int i;
struct iommu_pool *p;
@ -727,11 +726,9 @@ struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid,
/* number of bytes needed for the bitmap */
sz = BITS_TO_LONGS(tbl->it_size) * sizeof(unsigned long);
page = alloc_pages_node(nid, GFP_KERNEL, get_order(sz));
if (!page)
tbl->it_map = vzalloc_node(sz, nid);
if (!tbl->it_map)
panic("iommu_init_table: Can't allocate %ld bytes\n", sz);
tbl->it_map = page_address(page);
memset(tbl->it_map, 0, sz);
iommu_table_reserve_pages(tbl, res_start, res_end);
@ -773,8 +770,6 @@ struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid,
static void iommu_table_free(struct kref *kref)
{
unsigned long bitmap_sz;
unsigned int order;
struct iommu_table *tbl;
tbl = container_of(kref, struct iommu_table, it_kref);
@ -795,12 +790,8 @@ static void iommu_table_free(struct kref *kref)
if (!bitmap_empty(tbl->it_map, tbl->it_size))
pr_warn("%s: Unexpected TCEs\n", __func__);
/* calculate bitmap size in bytes */
bitmap_sz = BITS_TO_LONGS(tbl->it_size) * sizeof(unsigned long);
/* free bitmap */
order = get_order(bitmap_sz);
free_pages((unsigned long) tbl->it_map, order);
vfree(tbl->it_map);
/* free table */
kfree(tbl);