linux/drivers/iommu/io-pgtable.c
Boris Brezillon 17b226dcf8 iommu: Allow passing custom allocators to pgtable drivers
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

It might also be valuable for other aspects of GPU and similar
use-cases, like fine-grained memory accounting and resource limiting.

We will extend the Arm LPAE format to support custom allocators in a
separate commit.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20231124142434.1577550-2-boris.brezillon@collabora.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2023-11-27 11:10:12 +01:00

102 lines
2.5 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Generic page table allocator for IOMMUs.
*
* Copyright (C) 2014 ARM Limited
*
* Author: Will Deacon <will.deacon@arm.com>
*/
#include <linux/bug.h>
#include <linux/io-pgtable.h>
#include <linux/kernel.h>
#include <linux/types.h>
static const struct io_pgtable_init_fns *
io_pgtable_init_table[IO_PGTABLE_NUM_FMTS] = {
#ifdef CONFIG_IOMMU_IO_PGTABLE_LPAE
[ARM_32_LPAE_S1] = &io_pgtable_arm_32_lpae_s1_init_fns,
[ARM_32_LPAE_S2] = &io_pgtable_arm_32_lpae_s2_init_fns,
[ARM_64_LPAE_S1] = &io_pgtable_arm_64_lpae_s1_init_fns,
[ARM_64_LPAE_S2] = &io_pgtable_arm_64_lpae_s2_init_fns,
[ARM_MALI_LPAE] = &io_pgtable_arm_mali_lpae_init_fns,
#endif
#ifdef CONFIG_IOMMU_IO_PGTABLE_DART
[APPLE_DART] = &io_pgtable_apple_dart_init_fns,
[APPLE_DART2] = &io_pgtable_apple_dart_init_fns,
#endif
#ifdef CONFIG_IOMMU_IO_PGTABLE_ARMV7S
[ARM_V7S] = &io_pgtable_arm_v7s_init_fns,
#endif
#ifdef CONFIG_AMD_IOMMU
[AMD_IOMMU_V1] = &io_pgtable_amd_iommu_v1_init_fns,
[AMD_IOMMU_V2] = &io_pgtable_amd_iommu_v2_init_fns,
#endif
};
static int check_custom_allocator(enum io_pgtable_fmt fmt,
struct io_pgtable_cfg *cfg)
{
/* No custom allocator, no need to check the format. */
if (!cfg->alloc && !cfg->free)
return 0;
/* When passing a custom allocator, both the alloc and free
* functions should be provided.
*/
if (!cfg->alloc || !cfg->free)
return -EINVAL;
/* Make sure the format supports custom allocators. */
if (io_pgtable_init_table[fmt]->caps & IO_PGTABLE_CAP_CUSTOM_ALLOCATOR)
return 0;
return -EINVAL;
}
struct io_pgtable_ops *alloc_io_pgtable_ops(enum io_pgtable_fmt fmt,
struct io_pgtable_cfg *cfg,
void *cookie)
{
struct io_pgtable *iop;
const struct io_pgtable_init_fns *fns;
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;
iop = fns->alloc(cfg, cookie);
if (!iop)
return NULL;
iop->fmt = fmt;
iop->cookie = cookie;
iop->cfg = *cfg;
return &iop->ops;
}
EXPORT_SYMBOL_GPL(alloc_io_pgtable_ops);
/*
* It is the IOMMU driver's responsibility to ensure that the page table
* is no longer accessible to the walker by this point.
*/
void free_io_pgtable_ops(struct io_pgtable_ops *ops)
{
struct io_pgtable *iop;
if (!ops)
return;
iop = io_pgtable_ops_to_pgtable(ops);
io_pgtable_tlb_flush_all(iop);
io_pgtable_init_table[iop->fmt]->free(iop);
}
EXPORT_SYMBOL_GPL(free_io_pgtable_ops);