Commit 2db76d7c3c6d ("lib/scatterlist: sg_page_iter: support sg lists w/o backing pages") introduced the sg_page_iter_dma_address() function without providing a way to use it in the general case. If the sg_dma_len is not equal to the dma_length callers cannot safely use the for_each_sg_page/sg_page_iter_dma_address combination. Resolve this API mistake by providing a DMA specific iterator, for_each_sg_dma_page(), that uses the right length so sg_page_iter_dma_address() works as expected with all sglists. A new iterator type is introduced to provide compile-time safety against wrongly mixing accessors and iterators. Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx> --- drivers/gpu/drm/vmwgfx/vmwgfx_drv.h | 26 ++++++++++-- drivers/gpu/drm/vmwgfx/vmwgfx_mob.c | 26 +++++++----- drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c | 42 +++++++++++++------ drivers/media/pci/intel/ipu3/ipu3-cio2.c | 4 +- include/linux/scatterlist.h | 49 ++++++++++++++++++---- lib/scatterlist.c | 26 ++++++++++++ 6 files changed, 134 insertions(+), 39 deletions(-) I'd like to run this patch through the RDMA tree as we have another series in the works that wants to use the for_each_sg_dma_page() API. The changes to vmwgfx make me nervous, it would be great if someone could test and ack them? Changes since the RFC: - Rework vmwgfx too [CH] - Use a distinct type for the DMA page iterator [CH] - Do not have a #ifdef [CH] Thanks, Jason diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h index 59f614225bcd72..3c6d71e13a9342 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h @@ -297,7 +297,10 @@ struct vmw_sg_table { struct vmw_piter { struct page **pages; const dma_addr_t *addrs; - struct sg_page_iter iter; + union { + struct sg_page_iter iter; + struct sg_dma_page_iter dma_iter; + }; unsigned long i; unsigned long num_pages; bool (*next)(struct vmw_piter *); @@ -869,9 +872,24 @@ extern int vmw_bo_map_dma(struct ttm_buffer_object *bo); extern void vmw_bo_unmap_dma(struct ttm_buffer_object *bo); extern const struct vmw_sg_table * vmw_bo_sg_table(struct ttm_buffer_object *bo); -extern void vmw_piter_start(struct vmw_piter *viter, - const struct vmw_sg_table *vsgt, - unsigned long p_offs); +void _vmw_piter_start(struct vmw_piter *viter, const struct vmw_sg_table *vsgt, + unsigned long p_offs, bool for_dma); + +/* Create a piter that can call vmw_piter_dma_addr() */ +static inline void vmw_piter_start(struct vmw_piter *viter, + const struct vmw_sg_table *vsgt, + unsigned long p_offs) +{ + _vmw_piter_start(viter, vsgt, p_offs, true); +} + +/* Create a piter that can call vmw_piter_page() */ +static inline void vmw_piter_cpu_start(struct vmw_piter *viter, + const struct vmw_sg_table *vsgt, + unsigned long p_offs) +{ + _vmw_piter_start(viter, vsgt, p_offs, false); +} /** * vmw_piter_next - Advance the iterator one page. diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c b/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c index 7ed179d30ec51f..a13788017ad608 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_mob.c @@ -503,7 +503,8 @@ static void vmw_mob_assign_ppn(u32 **addr, dma_addr_t val) */ static unsigned long vmw_mob_build_pt(struct vmw_piter *data_iter, unsigned long num_data_pages, - struct vmw_piter *pt_iter) + struct vmw_piter *pt_iter_cpu, + struct vmw_piter *pt_iter_dma) { unsigned long pt_size = num_data_pages * VMW_PPN_SIZE; unsigned long num_pt_pages = DIV_ROUND_UP(pt_size, PAGE_SIZE); @@ -513,7 +514,7 @@ static unsigned long vmw_mob_build_pt(struct vmw_piter *data_iter, struct page *page; for (pt_page = 0; pt_page < num_pt_pages; ++pt_page) { - page = vmw_piter_page(pt_iter); + page = vmw_piter_page(pt_iter_cpu); save_addr = addr = kmap_atomic(page); @@ -525,7 +526,8 @@ static unsigned long vmw_mob_build_pt(struct vmw_piter *data_iter, WARN_ON(!vmw_piter_next(data_iter)); } kunmap_atomic(save_addr); - vmw_piter_next(pt_iter); + vmw_piter_next(pt_iter_cpu); + vmw_piter_next(pt_iter_dma); } return num_pt_pages; @@ -547,29 +549,31 @@ static void vmw_mob_pt_setup(struct vmw_mob *mob, { unsigned long num_pt_pages = 0; struct ttm_buffer_object *bo = mob->pt_bo; - struct vmw_piter save_pt_iter; - struct vmw_piter pt_iter; + struct vmw_piter pt_iter_cpu, pt_iter_dma; const struct vmw_sg_table *vsgt; + dma_addr_t root_page = 0; int ret; ret = ttm_bo_reserve(bo, false, true, NULL); BUG_ON(ret != 0); vsgt = vmw_bo_sg_table(bo); - vmw_piter_start(&pt_iter, vsgt, 0); - BUG_ON(!vmw_piter_next(&pt_iter)); + vmw_piter_start(&pt_iter_dma, vsgt, 0); + vmw_piter_cpu_start(&pt_iter_cpu, vsgt, 0); + BUG_ON(!vmw_piter_next(&pt_iter_cpu)); + BUG_ON(!vmw_piter_next(&pt_iter_dma)); mob->pt_level = 0; while (likely(num_data_pages > 1)) { ++mob->pt_level; BUG_ON(mob->pt_level > 2); - save_pt_iter = pt_iter; + root_page = vmw_piter_dma_addr(&pt_iter_dma); num_pt_pages = vmw_mob_build_pt(&data_iter, num_data_pages, - &pt_iter); - data_iter = save_pt_iter; + &pt_iter_cpu, &pt_iter_dma); + vmw_piter_start(&data_iter, vsgt, 0); num_data_pages = num_pt_pages; } - mob->pt_root_page = vmw_piter_dma_addr(&save_pt_iter); + mob->pt_root_page = root_page; ttm_bo_unreserve(bo); } diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c index 31786b200afc47..db8f3e40a4facb 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c @@ -269,6 +269,11 @@ static bool __vmw_piter_sg_next(struct vmw_piter *viter) return __sg_page_iter_next(&viter->iter); } +static bool __vmw_piter_sg_dma_next(struct vmw_piter *viter) +{ + return __sg_page_iter_dma_next(&viter->dma_iter); +} + /** * Helper functions to return a pointer to the current page. @@ -309,9 +314,9 @@ static dma_addr_t __vmw_piter_dma_addr(struct vmw_piter *viter) return viter->addrs[viter->i]; } -static dma_addr_t __vmw_piter_sg_addr(struct vmw_piter *viter) +static dma_addr_t __vmw_piter_sg_dma_addr(struct vmw_piter *viter) { - return sg_page_iter_dma_address(&viter->iter); + return sg_page_iter_dma_address(&viter->dma_iter); } @@ -325,32 +330,43 @@ static dma_addr_t __vmw_piter_sg_addr(struct vmw_piter *viter) * the iterator doesn't point to a valid page after initialization; it has * to be advanced one step first. */ -void vmw_piter_start(struct vmw_piter *viter, const struct vmw_sg_table *vsgt, - unsigned long p_offset) +void _vmw_piter_start(struct vmw_piter *viter, const struct vmw_sg_table *vsgt, + unsigned long p_offset, bool for_dma) { viter->i = p_offset - 1; viter->num_pages = vsgt->num_pages; switch (vsgt->mode) { case vmw_dma_phys: viter->next = &__vmw_piter_non_sg_next; - viter->dma_address = &__vmw_piter_phys_addr; - viter->page = &__vmw_piter_non_sg_page; + if (for_dma) + viter->dma_address = &__vmw_piter_phys_addr; + else + viter->page = &__vmw_piter_non_sg_page; viter->pages = vsgt->pages; break; case vmw_dma_alloc_coherent: viter->next = &__vmw_piter_non_sg_next; - viter->dma_address = &__vmw_piter_dma_addr; - viter->page = &__vmw_piter_non_sg_page; + if (for_dma) + viter->dma_address = &__vmw_piter_dma_addr; + else + viter->page = &__vmw_piter_non_sg_page; viter->addrs = vsgt->addrs; viter->pages = vsgt->pages; break; case vmw_dma_map_populate: case vmw_dma_map_bind: - viter->next = &__vmw_piter_sg_next; - viter->dma_address = &__vmw_piter_sg_addr; - viter->page = &__vmw_piter_sg_page; - __sg_page_iter_start(&viter->iter, vsgt->sgt->sgl, - vsgt->sgt->orig_nents, p_offset); + if (for_dma) { + viter->next = &__vmw_piter_sg_dma_next; + viter->dma_address = &__vmw_piter_sg_dma_addr; + __sg_page_iter_start(&viter->dma_iter.base, + vsgt->sgt->sgl, + vsgt->sgt->orig_nents, p_offset); + } else { + viter->next = &__vmw_piter_sg_next; + viter->page = &__vmw_piter_sg_page; + __sg_page_iter_start(&viter->iter, vsgt->sgt->sgl, + vsgt->sgt->orig_nents, p_offset); + } break; default: BUG(); diff --git a/drivers/media/pci/intel/ipu3/ipu3-cio2.c b/drivers/media/pci/intel/ipu3/ipu3-cio2.c index 447baaebca4486..32b6c6c217a46c 100644 --- a/drivers/media/pci/intel/ipu3/ipu3-cio2.c +++ b/drivers/media/pci/intel/ipu3/ipu3-cio2.c @@ -846,7 +846,7 @@ static int cio2_vb2_buf_init(struct vb2_buffer *vb) unsigned int pages = DIV_ROUND_UP(vb->planes[0].length, CIO2_PAGE_SIZE); unsigned int lops = DIV_ROUND_UP(pages + 1, entries_per_page); struct sg_table *sg; - struct sg_page_iter sg_iter; + struct sg_dma_page_iter sg_iter; int i, j; if (lops <= 0 || lops > CIO2_MAX_LOPS) { @@ -873,7 +873,7 @@ static int cio2_vb2_buf_init(struct vb2_buffer *vb) b->offset = sg->sgl->offset; i = j = 0; - for_each_sg_page(sg->sgl, &sg_iter, sg->nents, 0) { + for_each_sg_dma_page(sg->sgl, &sg_iter, sg->nents, 0) { if (!pages--) break; b->lop[i][j] = sg_page_iter_dma_address(&sg_iter) >> PAGE_SHIFT; diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index 093aa57120b0cf..c0592284e18b97 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -339,12 +339,12 @@ int sg_alloc_table_chained(struct sg_table *table, int nents, /* * sg page iterator * - * Iterates over sg entries page-by-page. On each successful iteration, - * you can call sg_page_iter_page(@piter) and sg_page_iter_dma_address(@piter) - * to get the current page and its dma address. @piter->sg will point to the - * sg holding this page and @piter->sg_pgoffset to the page's page offset - * within the sg. The iteration will stop either when a maximum number of sg - * entries was reached or a terminating sg (sg_last(sg) == true) was reached. + * Iterates over sg entries page-by-page. On each successful iteration, you + * can call sg_page_iter_page(@piter) to get the current page and its dma + * address. @piter->sg will point to the sg holding this page and + * @piter->sg_pgoffset to the page's page offset within the sg. The iteration + * will stop either when a maximum number of sg entries was reached or a + * terminating sg (sg_last(sg) == true) was reached. */ struct sg_page_iter { struct scatterlist *sg; /* sg holding the page */ @@ -356,7 +356,19 @@ struct sg_page_iter { * next step */ }; +/* + * sg page iterator for DMA addresses + * + * This is the same as sg_page_iter however you can call + * sg_page_iter_dma_address(@dma_iter) to get the page's DMA + * address. sg_page_iter_page() cannot be called on this iterator. + */ +struct sg_dma_page_iter { + struct sg_page_iter base; +}; + bool __sg_page_iter_next(struct sg_page_iter *piter); +bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter); void __sg_page_iter_start(struct sg_page_iter *piter, struct scatterlist *sglist, unsigned int nents, unsigned long pgoffset); @@ -372,11 +384,13 @@ static inline struct page *sg_page_iter_page(struct sg_page_iter *piter) /** * sg_page_iter_dma_address - get the dma address of the current page held by * the page iterator. - * @piter: page iterator holding the page + * @dma_iter: page iterator holding the page */ -static inline dma_addr_t sg_page_iter_dma_address(struct sg_page_iter *piter) +static inline dma_addr_t +sg_page_iter_dma_address(struct sg_dma_page_iter *dma_iter) { - return sg_dma_address(piter->sg) + (piter->sg_pgoffset << PAGE_SHIFT); + return sg_dma_address(dma_iter->base.sg) + + (dma_iter->base.sg_pgoffset << PAGE_SHIFT); } /** @@ -385,11 +399,28 @@ static inline dma_addr_t sg_page_iter_dma_address(struct sg_page_iter *piter) * @piter: page iterator to hold current page, sg, sg_pgoffset * @nents: maximum number of sg entries to iterate over * @pgoffset: starting page offset + * + * Callers may use sg_page_iter_page() to get each page pointer. */ #define for_each_sg_page(sglist, piter, nents, pgoffset) \ for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \ __sg_page_iter_next(piter);) +/** + * for_each_sg_dma_page - iterate over the pages of the given sg list + * @sglist: sglist to iterate over + * @dma_iter: page iterator to hold current page + * @dma_nents: maximum number of sg entries to iterate over, this is the value + * returned from dma_map_sg + * @pgoffset: starting page offset + * + * Callers may use sg_page_iter_dma_address() to get each page's DMA address. + */ +#define for_each_sg_dma_page(sglist, dma_iter, dma_nents, pgoffset) \ + for (__sg_page_iter_start(&(dma_iter)->base, sglist, dma_nents, \ + pgoffset); \ + __sg_page_iter_dma_next(dma_iter);) + /* * Mapping sg iterator * diff --git a/lib/scatterlist.c b/lib/scatterlist.c index 7c6096a7170486..716a751be67357 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -625,6 +625,32 @@ bool __sg_page_iter_next(struct sg_page_iter *piter) } EXPORT_SYMBOL(__sg_page_iter_next); +static int sg_dma_page_count(struct scatterlist *sg) +{ + return PAGE_ALIGN(sg->offset + sg_dma_len(sg)) >> PAGE_SHIFT; +} + +bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter) +{ + struct sg_page_iter *piter = &dma_iter->base; + + if (!piter->__nents || !piter->sg) + return false; + + piter->sg_pgoffset += piter->__pg_advance; + piter->__pg_advance = 1; + + while (piter->sg_pgoffset >= sg_dma_page_count(piter->sg)) { + piter->sg_pgoffset -= sg_dma_page_count(piter->sg); + piter->sg = sg_next(piter->sg); + if (!--piter->__nents || !piter->sg) + return false; + } + + return true; +} +EXPORT_SYMBOL(__sg_page_iter_next); + /** * sg_miter_start - start mapping iteration over a sg list * @miter: sg mapping iter to be started -- 2.20.1