Re: [Intel-gfx] [PATCH v7 06/15] drm/ttm: Add a generic TTM memcpy move for page-based iomem

Christian König
2021-05-31T12:37:09Z

Am 31.05.21 um 14:19 schrieb Thomas Hellström:
> The internal ttm_bo_util memcpy uses ioremap functionality, and while it
> probably might be possible to use it for copying in- and out of
> sglist represented io memory, using io_mem_reserve() / io_mem_free()
> callbacks, that would cause problems with fault().
> Instead, implement a method mapping page-by-page using kmap_local()
> semantics. As an additional benefit we then avoid the occasional global
> TLB flushes of ioremap() and consuming ioremap space, elimination of a
> critical point of failure and with a slight change of semantics we could
> also push the memcpy out async for testing and async driver development
> purposes.
>
> A special linear iomem iterator is introduced internally to mimic the
> old ioremap behaviour for code-paths that can't immediately be ported
> over. This adds to the code size and should be considered a temporary
> solution.
>
> Looking at the code we have a lot of checks for iomap tagged pointers.
> Ideally we should extend the core memremap functions to also accept
> uncached memory and kmap_local functionality. Then we could strip a
> lot of code.
>
> Cc: Christian König <christian.koenig@amd.com>
> Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> ---
> v3:
> - Split up in various TTM files and addressed review comments by
> Christian König. Tested and fixed legacy iomap memcpy path on i915.
> v4:
> - Fix an uninitialized variable
> Reported by: kernel test robot <lkp@intel.com>
> Reported by: Dan Carpenter <dan.carpenter@oracle.com>
> - Minor change to the ttm_move_memcpy() interface.
> - Gracefully handle lack of memremap() support on memcpy
> (Reported by Matthew Auld)
> - Minor style fix (Reported by Matthew Auld)
> ---
> drivers/gpu/drm/ttm/ttm_bo_util.c | 280 ++++++++++-------------------
> drivers/gpu/drm/ttm/ttm_module.c | 35 ++++
> drivers/gpu/drm/ttm/ttm_resource.c | 193 ++++++++++++++++++++
> drivers/gpu/drm/ttm/ttm_tt.c | 42 +++++
> include/drm/ttm/ttm_bo_driver.h | 28 +++
> include/drm/ttm/ttm_caching.h | 2 +
> include/drm/ttm/ttm_kmap_iter.h | 61 +++++++
> include/drm/ttm/ttm_resource.h | 61 +++++++
> include/drm/ttm/ttm_tt.h | 16 ++
> 9 files changed, 536 insertions(+), 182 deletions(-)
> create mode 100644 include/drm/ttm/ttm_kmap_iter.h
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
> index ae8b61460724..6ac7744a1a5c 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_util.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
> @@ -72,190 +72,126 @@ void ttm_mem_io_free(struct ttm_device *bdev,
> mem->bus.addr = NULL;
> }
>
> -static int ttm_resource_ioremap(struct ttm_device *bdev,
> - struct ttm_resource *mem,
> - void **virtual)
> +/**
> + * ttm_move_memcpy - Helper to perform a memcpy ttm move operation.
> + * @bo: The struct ttm_buffer_object.
> + * @new_mem: The struct ttm_resource we're moving to (copy destination).
> + * @new_iter: A struct ttm_kmap_iter representing the destination resource.
> + * @src_iter: A struct ttm_kmap_iter representing the source resource.
> + *
> + * This function is intended to be able to move out async under a
> + * dma-fence if desired.
> + */
> +void ttm_move_memcpy(struct ttm_buffer_object *bo,
> + pgoff_t num_pages,

Can we switch to uint32_t for num_pages for TTM in general?

That allows to copy 16TiB when you have 4KiB pages which should be
enough for quite a while and I had some really bad bugs because people
tend to do << PAGE_SHIFT and forget that it is only 32bit sometimes.

Apart from that feel free to stick my rb on the patch.

Christian.

> + struct ttm_kmap_iter *dst_iter,
> + struct ttm_kmap_iter *src_iter)
> {
> - int ret;
> - void *addr;
> -
> - *virtual = NULL;
> - ret = ttm_mem_io_reserve(bdev, mem);
> - if (ret || !mem->bus.is_iomem)
> - return ret;
> + const struct ttm_kmap_iter_ops *dst_ops = dst_iter->ops;
> + const struct ttm_kmap_iter_ops *src_ops = src_iter->ops;
> + struct ttm_tt *ttm = bo->ttm;
> + struct dma_buf_map src_map, dst_map;
> + pgoff_t i;
>
> - if (mem->bus.addr) {
> - addr = mem->bus.addr;
> - } else {
> - size_t bus_size = (size_t)mem->num_pages << PAGE_SHIFT;
> + /* Single TTM move. NOP */
> + if (dst_ops->maps_tt && src_ops->maps_tt)
> + return;
>
> - if (mem->bus.caching == ttm_write_combined)
> - addr = ioremap_wc(mem->bus.offset, bus_size);
> -#ifdef CONFIG_X86
> - else if (mem->bus.caching == ttm_cached)
> - addr = ioremap_cache(mem->bus.offset, bus_size);
> -#endif
> - else
> - addr = ioremap(mem->bus.offset, bus_size);
> - if (!addr) {
> - ttm_mem_io_free(bdev, mem);
> - return -ENOMEM;
> + /* Don't move nonexistent data. Clear destination instead. */
> + if (src_ops->maps_tt && (!ttm || !ttm_tt_is_populated(ttm))) {
> + if (ttm && !(ttm->page_flags & TTM_PAGE_FLAG_ZERO_ALLOC))
> + return;
> +
> + for (i = 0; i < num_pages; ++i) {
> + dst_ops->map_local(dst_iter, &dst_map, i);
> + if (dst_map.is_iomem)
> + memset_io(dst_map.vaddr_iomem, 0, PAGE_SIZE);
> + else
> + memset(dst_map.vaddr, 0, PAGE_SIZE);
> + if (dst_ops->unmap_local)
> + dst_ops->unmap_local(dst_iter, &dst_map);
> }
> + return;
> }
> - *virtual = addr;
> - return 0;
> -}
> -
> -static void ttm_resource_iounmap(struct ttm_device *bdev,
> - struct ttm_resource *mem,
> - void *virtual)
> -{
> - if (virtual && mem->bus.addr == NULL)
> - iounmap(virtual);
> - ttm_mem_io_free(bdev, mem);
> -}
> -
> -static int ttm_copy_io_page(void *dst, void *src, unsigned long page)
> -{
> - uint32_t *dstP =
> - (uint32_t *) ((unsigned long)dst + (page << PAGE_SHIFT));
> - uint32_t *srcP =
> - (uint32_t *) ((unsigned long)src + (page << PAGE_SHIFT));
> -
> - int i;
> - for (i = 0; i < PAGE_SIZE / sizeof(uint32_t); ++i)
> - iowrite32(ioread32(srcP++), dstP++);
> - return 0;
> -}
> -
> -static int ttm_copy_io_ttm_page(struct ttm_tt *ttm, void *src,
> - unsigned long page,
> - pgprot_t prot)
> -{
> - struct page *d = ttm->pages[page];
> - void *dst;
> -
> - if (!d)
> - return -ENOMEM;
> -
> - src = (void *)((unsigned long)src + (page << PAGE_SHIFT));
> - dst = kmap_atomic_prot(d, prot);
> - if (!dst)
> - return -ENOMEM;
> -
> - memcpy_fromio(dst, src, PAGE_SIZE);
> -
> - kunmap_atomic(dst);
> -
> - return 0;
> -}
> -
> -static int ttm_copy_ttm_io_page(struct ttm_tt *ttm, void *dst,
> - unsigned long page,
> - pgprot_t prot)
> -{
> - struct page *s = ttm->pages[page];
> - void *src;
>
> - if (!s)
> - return -ENOMEM;
> -
> - dst = (void *)((unsigned long)dst + (page << PAGE_SHIFT));
> - src = kmap_atomic_prot(s, prot);
> - if (!src)
> - return -ENOMEM;
> -
> - memcpy_toio(dst, src, PAGE_SIZE);
> -
> - kunmap_atomic(src);
> + for (i = 0; i < num_pages; ++i) {
> + dst_ops->map_local(dst_iter, &dst_map, i);
> + src_ops->map_local(src_iter, &src_map, i);
> +
> + if (!src_map.is_iomem && !dst_map.is_iomem) {
> + memcpy(dst_map.vaddr, src_map.vaddr, PAGE_SIZE);
> + } else if (!src_map.is_iomem) {
> + dma_buf_map_memcpy_to(&dst_map, src_map.vaddr,
> + PAGE_SIZE);
> + } else if (!dst_map.is_iomem) {
> + memcpy_fromio(dst_map.vaddr, src_map.vaddr_iomem,
> + PAGE_SIZE);
> + } else {
> + int j;
> + u32 __iomem *src = src_map.vaddr_iomem;
> + u32 __iomem *dst = dst_map.vaddr_iomem;
>
> - return 0;
> + for (j = 0; j < (PAGE_SIZE / sizeof(u32)); ++j)
> + iowrite32(ioread32(src++), dst++);
> + }
> + if (src_ops->unmap_local)
> + src_ops->unmap_local(src_iter, &src_map);
> + if (dst_ops->unmap_local)
> + dst_ops->unmap_local(dst_iter, &dst_map);
> + }
> }
> +EXPORT_SYMBOL(ttm_move_memcpy);
>
> int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
> struct ttm_operation_ctx *ctx,
> - struct ttm_resource *new_mem)
> + struct ttm_resource *dst_mem)
> {
> struct ttm_device *bdev = bo->bdev;
> - struct ttm_resource_manager *man = ttm_manager_type(bdev, new_mem->mem_type);
> + struct ttm_resource_manager *dst_man =
> + ttm_manager_type(bo->bdev, dst_mem->mem_type);
> struct ttm_tt *ttm = bo->ttm;
> - struct ttm_resource *old_mem = &bo->mem;
> - struct ttm_resource old_copy = *old_mem;
> - void *old_iomap;
> - void *new_iomap;
> - int ret;
> - unsigned long i;
> -
> - ret = ttm_bo_wait_ctx(bo, ctx);
> - if (ret)
> - return ret;
> -
> - ret = ttm_resource_ioremap(bdev, old_mem, &old_iomap);
> - if (ret)
> - return ret;
> - ret = ttm_resource_ioremap(bdev, new_mem, &new_iomap);
> - if (ret)
> - goto out;
> -
> - /*
> - * Single TTM move. NOP.
> - */
> - if (old_iomap == NULL && new_iomap == NULL)
> - goto out2;
> -
> - /*
> - * Don't move nonexistent data. Clear destination instead.
> - */
> - if (old_iomap == NULL &&
> - (ttm == NULL || (!ttm_tt_is_populated(ttm) &&
> - !(ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)))) {
> - memset_io(new_iomap, 0, new_mem->num_pages*PAGE_SIZE);
> - goto out2;
> - }
> + struct ttm_resource *src_mem = &bo->mem;
> + struct ttm_resource_manager *src_man =
> + ttm_manager_type(bdev, src_mem->mem_type);
> + struct ttm_resource src_copy = *src_mem;
> + union {
> + struct ttm_kmap_iter_tt tt;
> + struct ttm_kmap_iter_linear_io io;
> + } _dst_iter, _src_iter;
> + struct ttm_kmap_iter *dst_iter, *src_iter;
> + int ret = 0;
>
> - /*
> - * TTM might be null for moves within the same region.
> - */
> - if (ttm) {
> + if (ttm && ((ttm->page_flags & TTM_PAGE_FLAG_SWAPPED) ||
> + dst_man->use_tt)) {
> ret = ttm_tt_populate(bdev, ttm, ctx);
> if (ret)
> - goto out1;
> + return ret;
> }
>
> - for (i = 0; i < new_mem->num_pages; ++i) {
> - if (old_iomap == NULL) {
> - pgprot_t prot = ttm_io_prot(bo, old_mem, PAGE_KERNEL);
> - ret = ttm_copy_ttm_io_page(ttm, new_iomap, i,
> - prot);
> - } else if (new_iomap == NULL) {
> - pgprot_t prot = ttm_io_prot(bo, new_mem, PAGE_KERNEL);
> - ret = ttm_copy_io_ttm_page(ttm, old_iomap, i,
> - prot);
> - } else {
> - ret = ttm_copy_io_page(new_iomap, old_iomap, i);
> - }
> - if (ret)
> - goto out1;
> + dst_iter = ttm_kmap_iter_linear_io_init(&_dst_iter.io, bdev, dst_mem);
> + if (PTR_ERR(dst_iter) == -EINVAL && dst_man->use_tt)
> + dst_iter = ttm_kmap_iter_tt_init(&_dst_iter.tt, bo->ttm);
> + if (IS_ERR(dst_iter))
> + return PTR_ERR(dst_iter);
> +
> + src_iter = ttm_kmap_iter_linear_io_init(&_src_iter.io, bdev, src_mem);
> + if (PTR_ERR(src_iter) == -EINVAL && src_man->use_tt)
> + src_iter = ttm_kmap_iter_tt_init(&_src_iter.tt, bo->ttm);
> + if (IS_ERR(src_iter)) {
> + ret = PTR_ERR(src_iter);
> + goto out_src_iter;
> }
> - mb();
> -out2:
> - old_copy = *old_mem;
>
> - ttm_bo_assign_mem(bo, new_mem);
> -
> - if (!man->use_tt)
> - ttm_bo_tt_destroy(bo);
> + ttm_move_memcpy(bo, dst_mem->num_pages, dst_iter, src_iter);
> + src_copy = *src_mem;
> + ttm_bo_move_sync_cleanup(bo, dst_mem);
>
> -out1:
> - ttm_resource_iounmap(bdev, old_mem, new_iomap);
> -out:
> - ttm_resource_iounmap(bdev, &old_copy, old_iomap);
> + if (!src_iter->ops->maps_tt)
> + ttm_kmap_iter_linear_io_fini(&_src_iter.io, bdev, &src_copy);
> +out_src_iter:
> + if (!dst_iter->ops->maps_tt)
> + ttm_kmap_iter_linear_io_fini(&_dst_iter.io, bdev, dst_mem);
>
> - /*
> - * On error, keep the mm node!
> - */
> - if (!ret)
> - ttm_resource_free(bo, &old_copy);
> return ret;
> }
> EXPORT_SYMBOL(ttm_bo_move_memcpy);
> @@ -336,27 +272,7 @@ pgprot_t ttm_io_prot(struct ttm_buffer_object *bo, struct ttm_resource *res,
> man = ttm_manager_type(bo->bdev, res->mem_type);
> caching = man->use_tt ? bo->ttm->caching : res->bus.caching;
>
> - /* Cached mappings need no adjustment */
> - if (caching == ttm_cached)
> - return tmp;
> -
> -#if defined(__i386__) || defined(__x86_64__)
> - if (caching == ttm_write_combined)
> - tmp = pgprot_writecombine(tmp);
> - else if (boot_cpu_data.x86 > 3)
> - tmp = pgprot_noncached(tmp);
> -#endif
> -#if defined(__ia64__) || defined(__arm__) || defined(__aarch64__) || \
> - defined(__powerpc__) || defined(__mips__)
> - if (caching == ttm_write_combined)
> - tmp = pgprot_writecombine(tmp);
> - else
> - tmp = pgprot_noncached(tmp);
> -#endif
> -#if defined(__sparc__)
> - tmp = pgprot_noncached(tmp);
> -#endif
> - return tmp;
> + return ttm_prot_from_caching(caching, tmp);
> }
> EXPORT_SYMBOL(ttm_io_prot);
>
> diff --git a/drivers/gpu/drm/ttm/ttm_module.c b/drivers/gpu/drm/ttm/ttm_module.c
> index 56b0efdba1a9..997c458f68a9 100644
> --- a/drivers/gpu/drm/ttm/ttm_module.c
> +++ b/drivers/gpu/drm/ttm/ttm_module.c
> @@ -31,12 +31,47 @@
> */
> #include <linux/module.h>
> #include <linux/device.h>
> +#include <linux/pgtable.h>
> #include <linux/sched.h>
> #include <linux/debugfs.h>
> #include <drm/drm_sysfs.h>
> +#include <drm/ttm/ttm_caching.h>
>
> #include "ttm_module.h"
>
> +/**
> + * ttm_prot_from_caching - Modify the page protection according to the
> + * ttm cacing mode
> + * @caching: The ttm caching mode
> + * @tmp: The original page protection
> + *
> + * Return: The modified page protection
> + */
> +pgprot_t ttm_prot_from_caching(enum ttm_caching caching, pgprot_t tmp)
> +{
> + /* Cached mappings need no adjustment */
> + if (caching == ttm_cached)
> + return tmp;
> +
> +#if defined(__i386__) || defined(__x86_64__)
> + if (caching == ttm_write_combined)
> + tmp = pgprot_writecombine(tmp);
> + else if (boot_cpu_data.x86 > 3)
> + tmp = pgprot_noncached(tmp);
> +#endif
> +#if defined(__ia64__) || defined(__arm__) || defined(__aarch64__) || \
> + defined(__powerpc__) || defined(__mips__)
> + if (caching == ttm_write_combined)
> + tmp = pgprot_writecombine(tmp);
> + else
> + tmp = pgprot_noncached(tmp);
> +#endif
> +#if defined(__sparc__)
> + tmp = pgprot_noncached(tmp);
> +#endif
> + return tmp;
> +}
> +
> struct dentry *ttm_debugfs_root;
>
> static int __init ttm_init(void)
> diff --git a/drivers/gpu/drm/ttm/ttm_resource.c b/drivers/gpu/drm/ttm/ttm_resource.c
> index 59e2b7157e41..931bcd1a9b9b 100644
> --- a/drivers/gpu/drm/ttm/ttm_resource.c
> +++ b/drivers/gpu/drm/ttm/ttm_resource.c
> @@ -22,6 +22,10 @@
> * Authors: Christian König
> */
>
> +#include <linux/dma-buf-map.h>
> +#include <linux/io-mapping.h>
> +#include <linux/scatterlist.h>
> +
> #include <drm/ttm/ttm_resource.h>
> #include <drm/ttm/ttm_bo_driver.h>
>
> @@ -147,3 +151,192 @@ void ttm_resource_manager_debug(struct ttm_resource_manager *man,
> man->func->debug(man, p);
> }
> EXPORT_SYMBOL(ttm_resource_manager_debug);
> +
> +static void ttm_kmap_iter_iomap_map_local(struct ttm_kmap_iter *iter,
> + struct dma_buf_map *dmap,
> + pgoff_t i)
> +{
> + struct ttm_kmap_iter_iomap *iter_io =
> + container_of(iter, typeof(*iter_io), base);
> + void __iomem *addr;
> +
> +retry:
> + while (i >= iter_io->cache.end) {
> + iter_io->cache.sg = iter_io->cache.sg ?
> + sg_next(iter_io->cache.sg) : iter_io->st->sgl;
> + iter_io->cache.i = iter_io->cache.end;
> + iter_io->cache.end += sg_dma_len(iter_io->cache.sg) >>
> + PAGE_SHIFT;
> + iter_io->cache.offs = sg_dma_address(iter_io->cache.sg) -
> + iter_io->start;
> + }
> +
> + if (i < iter_io->cache.i) {
> + iter_io->cache.end = 0;
> + iter_io->cache.sg = NULL;
> + goto retry;
> + }
> +
> + addr = io_mapping_map_local_wc(iter_io->iomap, iter_io->cache.offs +
> + (((resource_size_t)i - iter_io->cache.i)
> + << PAGE_SHIFT));
> + dma_buf_map_set_vaddr_iomem(dmap, addr);
> +}
> +
> +static void ttm_kmap_iter_iomap_unmap_local(struct ttm_kmap_iter *iter,
> + struct dma_buf_map *map)
> +{
> + io_mapping_unmap_local(map->vaddr_iomem);
> +}
> +
> +static const struct ttm_kmap_iter_ops ttm_kmap_iter_io_ops = {
> + .map_local = ttm_kmap_iter_iomap_map_local,
> + .unmap_local = ttm_kmap_iter_iomap_unmap_local,
> + .maps_tt = false,
> +};
> +
> +/**
> + * ttm_kmap_iter_iomap_init - Initialize a struct ttm_kmap_iter_iomap
> + * @iter_io: The struct ttm_kmap_iter_iomap to initialize.
> + * @iomap: The struct io_mapping representing the underlying linear io_memory.
> + * @st: sg_table into @iomap, representing the memory of the struct
> + * ttm_resource.
> + * @start: Offset that needs to be subtracted from @st to make
> + * sg_dma_address(st->sgl) - @start == 0 for @iomap start.
> + *
> + * Return: Pointer to the embedded struct ttm_kmap_iter.
> + */
> +struct ttm_kmap_iter *
> +ttm_kmap_iter_iomap_init(struct ttm_kmap_iter_iomap *iter_io,
> + struct io_mapping *iomap,
> + struct sg_table *st,
> + resource_size_t start)
> +{
> + iter_io->base.ops = &ttm_kmap_iter_io_ops;
> + iter_io->iomap = iomap;
> + iter_io->st = st;
> + iter_io->start = start;
> + memset(&iter_io->cache, 0, sizeof(iter_io->cache));
> +
> + return &iter_io->base;
> +}
> +EXPORT_SYMBOL(ttm_kmap_iter_iomap_init);
> +
> +/**
> + * DOC: Linear io iterator
> + *
> + * This code should die in the not too near future. Best would be if we could
> + * make io-mapping use memremap for all io memory, and have memremap
> + * implement a kmap_local functionality. We could then strip a huge amount of
> + * code. These linear io iterators are implemented to mimic old functionality,
> + * and they don't use kmap_local semantics at all internally. Rather ioremap or
> + * friends, and at least on 32-bit they add global TLB flushes and points
> + * of failure.
> + */
> +
> +static void ttm_kmap_iter_linear_io_map_local(struct ttm_kmap_iter *iter,
> + struct dma_buf_map *dmap,
> + pgoff_t i)
> +{
> + struct ttm_kmap_iter_linear_io *iter_io =
> + container_of(iter, typeof(*iter_io), base);
> +
> + *dmap = iter_io->dmap;
> + dma_buf_map_incr(dmap, i * PAGE_SIZE);
> +}
> +
> +static const struct ttm_kmap_iter_ops ttm_kmap_iter_linear_io_ops = {
> + .map_local = ttm_kmap_iter_linear_io_map_local,
> + .maps_tt = false,
> +};
> +
> +/**
> + * ttm_kmap_iter_linear_io_init - Initialize an iterator for linear io memory
> + * @iter_io: The iterator to initialize
> + * @bdev: The TTM device
> + * @mem: The ttm resource representing the iomap.
> + *
> + * This function is for internal TTM use only. It sets up a memcpy kmap iterator
> + * pointing at a linear chunk of io memory.
> + *
> + * Return: A pointer to the embedded struct ttm_kmap_iter or error pointer on
> + * failure.
> + */
> +struct ttm_kmap_iter *
> +ttm_kmap_iter_linear_io_init(struct ttm_kmap_iter_linear_io *iter_io,
> + struct ttm_device *bdev,
> + struct ttm_resource *mem)
> +{
> + int ret;
> +
> + ret = ttm_mem_io_reserve(bdev, mem);
> + if (ret)
> + goto out_err;
> + if (!mem->bus.is_iomem) {
> + ret = -EINVAL;
> + goto out_io_free;
> + }
> +
> + if (mem->bus.addr) {
> + dma_buf_map_set_vaddr(&iter_io->dmap, mem->bus.addr);
> + iter_io->needs_unmap = false;
> + } else {
> + size_t bus_size = (size_t)mem->num_pages << PAGE_SHIFT;
> +
> + iter_io->needs_unmap = true;
> + memset(&iter_io->dmap, 0, sizeof(iter_io->dmap));
> + if (mem->bus.caching == ttm_write_combined)
> + dma_buf_map_set_vaddr_iomem(&iter_io->dmap,
> + ioremap_wc(mem->bus.offset,
> + bus_size));
> + else if (mem->bus.caching == ttm_cached)
> + dma_buf_map_set_vaddr(&iter_io->dmap,
> + memremap(mem->bus.offset, bus_size,
> + MEMREMAP_WB |
> + MEMREMAP_WT |
> + MEMREMAP_WC));
> +
> + /* If uncached requested or if mapping cached or wc failed */
> + if (dma_buf_map_is_null(&iter_io->dmap))
> + dma_buf_map_set_vaddr_iomem(&iter_io->dmap,
> + ioremap(mem->bus.offset,
> + bus_size));
> +
> + if (dma_buf_map_is_null(&iter_io->dmap)) {
> + ret = -ENOMEM;
> + goto out_io_free;
> + }
> + }
> +
> + iter_io->base.ops = &ttm_kmap_iter_linear_io_ops;
> + return &iter_io->base;
> +
> +out_io_free:
> + ttm_mem_io_free(bdev, mem);
> +out_err:
> + return ERR_PTR(ret);
> +}
> +
> +/**
> + * ttm_kmap_iter_linear_io_fini - Clean up an iterator for linear io memory
> + * @iter_io: The iterator to initialize
> + * @bdev: The TTM device
> + * @mem: The ttm resource representing the iomap.
> + *
> + * This function is for internal TTM use only. It cleans up a memcpy kmap
> + * iterator initialized by ttm_kmap_iter_linear_io_init.
> + */
> +void
> +ttm_kmap_iter_linear_io_fini(struct ttm_kmap_iter_linear_io *iter_io,
> + struct ttm_device *bdev,
> + struct ttm_resource *mem)
> +{
> + if (iter_io->needs_unmap && dma_buf_map_is_set(&iter_io->dmap)) {
> + if (iter_io->dmap.is_iomem)
> + iounmap(iter_io->dmap.vaddr_iomem);
> + else
> + memunmap(iter_io->dmap.vaddr);
> + }
> +
> + ttm_mem_io_free(bdev, mem);
> +}
> diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
> index 539e0232cb3b..0e41227116b1 100644
> --- a/drivers/gpu/drm/ttm/ttm_tt.c
> +++ b/drivers/gpu/drm/ttm/ttm_tt.c
> @@ -433,3 +433,45 @@ void ttm_tt_mgr_init(unsigned long num_pages, unsigned long num_dma32_pages)
> if (!ttm_dma32_pages_limit)
> ttm_dma32_pages_limit = num_dma32_pages;
> }
> +
> +static void ttm_kmap_iter_tt_map_local(struct ttm_kmap_iter *iter,
> + struct dma_buf_map *dmap,
> + pgoff_t i)
> +{
> + struct ttm_kmap_iter_tt *iter_tt =
> + container_of(iter, typeof(*iter_tt), base);
> +
> + dma_buf_map_set_vaddr(dmap, kmap_local_page_prot(iter_tt->tt->pages[i],
> + iter_tt->prot));
> +}
> +
> +static void ttm_kmap_iter_tt_unmap_local(struct ttm_kmap_iter *iter,
> + struct dma_buf_map *map)
> +{
> + kunmap_local(map->vaddr);
> +}
> +
> +static const struct ttm_kmap_iter_ops ttm_kmap_iter_tt_ops = {
> + .map_local = ttm_kmap_iter_tt_map_local,
> + .unmap_local = ttm_kmap_iter_tt_unmap_local,
> + .maps_tt = true,
> +};
> +
> +/**
> + * ttm_kmap_iter_tt_init - Initialize a struct ttm_kmap_iter_tt
> + * @iter_tt: The struct ttm_kmap_iter_tt to initialize.
> + * @tt: Struct ttm_tt holding page pointers of the struct ttm_resource.
> + *
> + * Return: Pointer to the embedded struct ttm_kmap_iter.
> + */
> +struct ttm_kmap_iter *
> +ttm_kmap_iter_tt_init(struct ttm_kmap_iter_tt *iter_tt,
> + struct ttm_tt *tt)
> +{
> + iter_tt->base.ops = &ttm_kmap_iter_tt_ops;
> + iter_tt->tt = tt;
> + iter_tt->prot = ttm_prot_from_caching(tt->caching, PAGE_KERNEL);
> +
> + return &iter_tt->base;
> +}
> +EXPORT_SYMBOL(ttm_kmap_iter_tt_init);
> diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
> index dbccac957f8f..fdbeac78c236 100644
> --- a/include/drm/ttm/ttm_bo_driver.h
> +++ b/include/drm/ttm/ttm_bo_driver.h
> @@ -40,6 +40,7 @@
> #include <drm/ttm/ttm_device.h>
>
> #include "ttm_bo_api.h"
> +#include "ttm_kmap_iter.h"
> #include "ttm_placement.h"
> #include "ttm_tt.h"
> #include "ttm_pool.h"
> @@ -272,6 +273,23 @@ int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo,
> bool pipeline,
> struct ttm_resource *new_mem);
>
> +/**
> + * ttm_bo_move_accel_cleanup.
> + *
> + * @bo: A pointer to a struct ttm_buffer_object.
> + * @new_mem: struct ttm_resource indicating where to move.
> + *
> + * Special case of ttm_bo_move_accel_cleanup where the bo is guaranteed
> + * by the caller to be idle. Typically used after memcpy buffer moves.
> + */
> +static inline void ttm_bo_move_sync_cleanup(struct ttm_buffer_object *bo,
> + struct ttm_resource *new_mem)
> +{
> + int ret = ttm_bo_move_accel_cleanup(bo, NULL, true, false, new_mem);
> +
> + WARN_ON(ret);
> +}
> +
> /**
> * ttm_bo_pipeline_gutting.
> *
> @@ -332,4 +350,14 @@ int ttm_range_man_init(struct ttm_device *bdev,
> int ttm_range_man_fini(struct ttm_device *bdev,
> unsigned type);
>
> +void ttm_move_memcpy(struct ttm_buffer_object *bo,
> + pgoff_t num_pages,
> + struct ttm_kmap_iter *dst_iter,
> + struct ttm_kmap_iter *src_iter);
> +
> +struct ttm_kmap_iter *
> +ttm_kmap_iter_iomap_init(struct ttm_kmap_iter_iomap *iter_io,
> + struct io_mapping *iomap,
> + struct sg_table *st,
> + resource_size_t start);
> #endif
> diff --git a/include/drm/ttm/ttm_caching.h b/include/drm/ttm/ttm_caching.h
> index a0b4a49fa432..3c9dd65f5aaf 100644
> --- a/include/drm/ttm/ttm_caching.h
> +++ b/include/drm/ttm/ttm_caching.h
> @@ -33,4 +33,6 @@ enum ttm_caching {
> ttm_cached
> };
>
> +pgprot_t ttm_prot_from_caching(enum ttm_caching caching, pgprot_t tmp);
> +
> #endif
> diff --git a/include/drm/ttm/ttm_kmap_iter.h b/include/drm/ttm/ttm_kmap_iter.h
> new file mode 100644
> index 000000000000..8bb00fd39d6c
> --- /dev/null
> +++ b/include/drm/ttm/ttm_kmap_iter.h
> @@ -0,0 +1,61 @@
> +/* SPDX-License-Identifier: MIT */
> +/*
> + * Copyright © 2021 Intel Corporation
> + */
> +#ifndef __TTM_KMAP_ITER_H__
> +#define __TTM_KMAP_ITER_H__
> +
> +#include <linux/types.h>
> +
> +struct ttm_kmap_iter;
> +struct dma_buf_map;
> +
> +/**
> + * struct ttm_kmap_iter_ops - Ops structure for a struct
> + * ttm_kmap_iter.
> + * @maps_tt: Whether the iterator maps TT memory directly, as opposed
> + * mapping a TT through an aperture. Both these modes have
> + * struct ttm_resource_manager::use_tt set, but the latter typically
> + * returns is_iomem == true from ttm_mem_io_reserve.
> + */
> +struct ttm_kmap_iter_ops {
> + /**
> + * kmap_local() - Map a PAGE_SIZE part of the resource using
> + * kmap_local semantics.
> + * @res_iter: Pointer to the struct ttm_kmap_iter representing
> + * the resource.
> + * @dmap: The struct dma_buf_map holding the virtual address after
> + * the operation.
> + * @i: The location within the resource to map. PAGE_SIZE granularity.
> + */
> + void (*map_local)(struct ttm_kmap_iter *res_iter,
> + struct dma_buf_map *dmap, pgoff_t i);
> + /**
> + * unmap_local() - Unmap a PAGE_SIZE part of the resource previously
> + * mapped using kmap_local.
> + * @res_iter: Pointer to the struct ttm_kmap_iter representing
> + * the resource.
> + * @dmap: The struct dma_buf_map holding the virtual address after
> + * the operation.
> + */
> + void (*unmap_local)(struct ttm_kmap_iter *res_iter,
> + struct dma_buf_map *dmap);
> + bool maps_tt;
> +};
> +
> +/**
> + * struct ttm_kmap_iter - Iterator for kmap_local type operations on a
> + * resource.
> + * @ops: Pointer to the operations struct.
> + *
> + * This struct is intended to be embedded in a resource-specific specialization
> + * implementing operations for the resource.
> + *
> + * Nothing stops us from extending the operations to vmap, vmap_pfn etc,
> + * replacing some or parts of the ttm_bo_util. cpu-map functionality.
> + */
> +struct ttm_kmap_iter {
> + const struct ttm_kmap_iter_ops *ops;
> +};
> +
> +#endif /* __TTM_KMAP_ITER_H__ */
> diff --git a/include/drm/ttm/ttm_resource.h b/include/drm/ttm/ttm_resource.h
> index 890b9d369519..b8dc0bdb0da5 100644
> --- a/include/drm/ttm/ttm_resource.h
> +++ b/include/drm/ttm/ttm_resource.h
> @@ -27,9 +27,11 @@
>
> #include <linux/types.h>
> #include <linux/mutex.h>
> +#include <linux/dma-buf-map.h>
> #include <linux/dma-fence.h>
> #include <drm/drm_print.h>
> #include <drm/ttm/ttm_caching.h>
> +#include <drm/ttm/ttm_kmap_iter.h>
>
> #define TTM_MAX_BO_PRIORITY 4U
>
> @@ -38,6 +40,10 @@ struct ttm_resource_manager;
> struct ttm_resource;
> struct ttm_place;
> struct ttm_buffer_object;
> +struct dma_buf_map;
> +struct io_mapping;
> +struct sg_table;
> +struct scatterlist;
>
> struct ttm_resource_manager_func {
> /**
> @@ -176,6 +182,45 @@ struct ttm_resource {
> struct ttm_bus_placement bus;
> };
>
> +/**
> + * struct ttm_kmap_iter_iomap - Specialization for a struct io_mapping +
> + * struct sg_table backed struct ttm_resource.
> + * @base: Embedded struct ttm_kmap_iter providing the usage interface.
> + * @iomap: struct io_mapping representing the underlying linear io_memory.
> + * @st: sg_table into @iomap, representing the memory of the struct ttm_resource.
> + * @start: Offset that needs to be subtracted from @st to make
> + * sg_dma_address(st->sgl) - @start == 0 for @iomap start.
> + * @cache: Scatterlist traversal cache for fast lookups.
> + * @cache.sg: Pointer to the currently cached scatterlist segment.
> + * @cache.i: First index of @sg. PAGE_SIZE granularity.
> + * @cache.end: Last index + 1 of @sg. PAGE_SIZE granularity.
> + * @cache.offs: First offset into @iomap of @sg. PAGE_SIZE granularity.
> + */
> +struct ttm_kmap_iter_iomap {
> + struct ttm_kmap_iter base;
> + struct io_mapping *iomap;
> + struct sg_table *st;
> + resource_size_t start;
> + struct {
> + struct scatterlist *sg;
> + pgoff_t i;
> + pgoff_t end;
> + pgoff_t offs;
> + } cache;
> +};
> +
> +/**
> + * struct ttm_kmap_iter_linear_io - Iterator specialization for linear io
> + * @base: The base iterator
> + * @dmap: Points to the starting address of the region
> + * @needs_unmap: Whether we need to unmap on fini
> + */
> +struct ttm_kmap_iter_linear_io {
> + struct ttm_kmap_iter base;
> + struct dma_buf_map dmap;
> + bool needs_unmap;
> +};
> +
> /**
> * ttm_resource_manager_set_used
> *
> @@ -237,4 +282,20 @@ int ttm_resource_manager_evict_all(struct ttm_device *bdev,
> void ttm_resource_manager_debug(struct ttm_resource_manager *man,
> struct drm_printer *p);
>
> +struct ttm_kmap_iter *
> +ttm_kmap_iter_iomap_init(struct ttm_kmap_iter_iomap *iter_io,
> + struct io_mapping *iomap,
> + struct sg_table *st,
> + resource_size_t start);
> +
> +struct ttm_kmap_iter_linear_io;
> +
> +struct ttm_kmap_iter *
> +ttm_kmap_iter_linear_io_init(struct ttm_kmap_iter_linear_io *iter_io,
> + struct ttm_device *bdev,
> + struct ttm_resource *mem);
> +
> +void ttm_kmap_iter_linear_io_fini(struct ttm_kmap_iter_linear_io *iter_io,
> + struct ttm_device *bdev,
> + struct ttm_resource *mem);
> #endif
> diff --git a/include/drm/ttm/ttm_tt.h b/include/drm/ttm/ttm_tt.h
> index 134d09ef7766..3102059db726 100644
> --- a/include/drm/ttm/ttm_tt.h
> +++ b/include/drm/ttm/ttm_tt.h
> @@ -29,6 +29,7 @@
>
> #include <linux/types.h>
> #include <drm/ttm/ttm_caching.h>
> +#include <drm/ttm/ttm_kmap_iter.h>
>
> struct ttm_bo_device;
> struct ttm_tt;
> @@ -69,6 +70,18 @@ struct ttm_tt {
> enum ttm_caching caching;
> };
>
> +/**
> + * struct ttm_kmap_iter_tt - Specialization of a mappig iterator for a tt.
> + * @base: Embedded struct ttm_kmap_iter providing the usage interface
> + * @tt: Cached struct ttm_tt.
> + * @prot: Cached page protection for mapping.
> + */
> +struct ttm_kmap_iter_tt {
> + struct ttm_kmap_iter base;
> + struct ttm_tt *tt;
> + pgprot_t prot;
> +};
> +
> static inline bool ttm_tt_is_populated(struct ttm_tt *tt)
> {
> return tt->page_flags & TTM_PAGE_FLAG_PRIV_POPULATED;
> @@ -159,6 +172,9 @@ void ttm_tt_unpopulate(struct ttm_device *bdev, struct ttm_tt *ttm);
>
> void ttm_tt_mgr_init(unsigned long num_pages, unsigned long num_dma32_pages);
>
> +struct ttm_kmap_iter *ttm_kmap_iter_tt_init(struct ttm_kmap_iter_tt *iter_tt,
> + struct ttm_tt *tt);
> +
> #if IS_ENABLED(CONFIG_AGP)
> #include <linux/agp_backend.h>
>