@@ -34,6 +34,22 @@ io_pgtable_init_table[IO_PGTABLE_NUM_FMTS] = {
#endif
};
+static int check_custom_allocator(enum io_pgtable_fmt fmt,
+ struct io_pgtable_cfg *cfg)
+{
+ /* When passing a custom allocator, both the alloc and free
+ * functions should be provided.
+ */
+ if ((cfg->alloc != NULL) != (cfg->free != NULL))
+ return -EINVAL;
+
+ /* No custom allocator, no need to check the format. */
+ if (!cfg->alloc)
+ return 0;
+
+ return -EINVAL;
+}
+
struct io_pgtable_ops *alloc_io_pgtable_ops(enum io_pgtable_fmt fmt,
struct io_pgtable_cfg *cfg,
void *cookie)
@@ -44,6 +60,9 @@ struct io_pgtable_ops *alloc_io_pgtable_ops(enum io_pgtable_fmt fmt,
if (fmt >= IO_PGTABLE_NUM_FMTS)
return NULL;
+ if (check_custom_allocator(fmt, cfg))
+ return NULL;
+
fns = io_pgtable_init_table[fmt];
if (!fns)
return NULL;
@@ -100,6 +100,27 @@ struct io_pgtable_cfg {
const struct iommu_flush_ops *tlb;
struct device *iommu_dev;
+ /**
+ * @alloc: Custom page allocator.
+ *
+ * Optional hook used to allocate page tables. If this function is NULL,
+ * @free must be NULL too.
+ *
+ * Not all formats support custom page allocators. Before considering
+ * passing a non-NULL value, make sure the chosen page format supports
+ * this feature.
+ */
+ void *(*alloc)(void *cookie, size_t size, gfp_t gfp);
+
+ /**
+ * @free: Custom page de-allocator.
+ *
+ * Optional hook used to free page tables allocated with the @alloc
+ * hook. Must be non-NULL if @alloc is not NULL, must be NULL
+ * otherwise.
+ */
+ void (*free)(void *cookie, void *pages, size_t size);
+
/* Low-level data specific to the table format */
union {
struct {
This will be useful for GPU drivers who want to keep page tables in a pool so they can: - keep freed page tables in a free pool and speed-up upcoming page table allocations - batch page table allocation instead of allocating one page at a time - pre-reserve pages for page tables needed for map/unmap operations, to ensure map/unmap operations don't try to allocate memory in paths they're allowed to block or fail We will extend the Arm LPAE format to support custom allocators in a separate commit. Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com> --- drivers/iommu/io-pgtable.c | 19 +++++++++++++++++++ include/linux/io-pgtable.h | 21 +++++++++++++++++++++ 2 files changed, 40 insertions(+)