On Fri, 21 May 2021 at 16:33, Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx> wrote: > > 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@xxxxxxx> > Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx> > --- > v3: > - Split up in various TTM files and addressed review comments by > Christian König. Tested and fixed legacy iomap memcpy path on i915. > --- > drivers/gpu/drm/ttm/ttm_bo_util.c | 278 ++++++++++------------------- > drivers/gpu/drm/ttm/ttm_module.c | 35 ++++ > drivers/gpu/drm/ttm/ttm_resource.c | 166 +++++++++++++++++ > 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, 508 insertions(+), 181 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..912cbe8e60a2 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, > + struct ttm_resource *dst_mem, > + 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 < dst_mem->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 < dst_mem->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 >> 2); ++j) IMO PAGE_SIZE / sizeof(u32) is easier to understand. > + 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; > + 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; > - 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; > - } > - > - /* > - * 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, 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..e05ae7e3d477 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 +151,165 @@ 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, > +}; > + > +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; > + 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)); The comments in set_vaddr suggest that this is meant for system-memory. Does that actually matter or is it just about not losing the __iomem annotation on platforms where it matters? Apparently cached device local is a thing. Also should this not be wrapped in CONFIG_X86?