The dma-map IOVA alloc, link, and sync APIs perform significantly better than dma-map / dma-unmap, as they avoid costly IOMMU synchronizations. This difference is especially noticeable when mapping a 2MB region in 4KB pages.
Use the IOVA alloc, link, and sync APIs for GPU SVM, which create DMA mappings between the CPU and GPU. Signed-off-by: Matthew Brost <[email protected]> --- v3: - Always link IOVA in mixed mappings - Sync IOVA v4: - Initialize IOVA state in get_pages - Use pack IOVA linking (Jason) - s/page_to_phys/hmm_pfn_to_phys (Leon) drivers/gpu/drm/drm_gpusvm.c | 55 ++++++++++++++++++++++++++++++------ include/drm/drm_gpusvm.h | 5 ++++ 2 files changed, 52 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c index 4b8130a4ce95..800caaf0a783 100644 --- a/drivers/gpu/drm/drm_gpusvm.c +++ b/drivers/gpu/drm/drm_gpusvm.c @@ -1139,11 +1139,19 @@ static void __drm_gpusvm_unmap_pages(struct drm_gpusvm *gpusvm, struct drm_gpusvm_pages_flags flags = { .__flags = svm_pages->flags.__flags, }; + bool use_iova = dma_use_iova(&svm_pages->state); + + if (use_iova) { + dma_iova_unlink(dev, &svm_pages->state, 0, + svm_pages->state_offset, + svm_pages->dma_addr[0].dir, 0); + dma_iova_free(dev, &svm_pages->state); + } for (i = 0, j = 0; i < npages; j++) { struct drm_pagemap_addr *addr = &svm_pages->dma_addr[j]; - if (addr->proto == DRM_INTERCONNECT_SYSTEM) + if (!use_iova && addr->proto == DRM_INTERCONNECT_SYSTEM) dma_unmap_page(dev, addr->addr, PAGE_SIZE << addr->order, @@ -1408,6 +1416,7 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm, struct drm_gpusvm_pages_flags flags; enum dma_data_direction dma_dir = ctx->read_only ? DMA_TO_DEVICE : DMA_BIDIRECTIONAL; + struct dma_iova_state *state = &svm_pages->state; retry: if (time_after(jiffies, timeout)) @@ -1446,6 +1455,9 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm, if (err) goto err_free; + *state = (struct dma_iova_state){}; + svm_pages->state_offset = 0; + map_pages: /* * Perform all dma mappings under the notifier lock to not @@ -1539,13 +1551,33 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm, goto err_unmap; } - addr = dma_map_page(gpusvm->drm->dev, - page, 0, - PAGE_SIZE << order, - dma_dir); - if (dma_mapping_error(gpusvm->drm->dev, addr)) { - err = -EFAULT; - goto err_unmap; + if (!i) + dma_iova_try_alloc(gpusvm->drm->dev, state, + npages * PAGE_SIZE >= + HPAGE_PMD_SIZE ? + HPAGE_PMD_SIZE : 0, + npages * PAGE_SIZE); + + if (dma_use_iova(state)) { + err = dma_iova_link(gpusvm->drm->dev, state, + hmm_pfn_to_phys(pfns[i]), + svm_pages->state_offset, + PAGE_SIZE << order, + dma_dir, 0); + if (err) + goto err_unmap; + + addr = state->addr + svm_pages->state_offset; + svm_pages->state_offset += PAGE_SIZE << order; + } else { + addr = dma_map_page(gpusvm->drm->dev, + page, 0, + PAGE_SIZE << order, + dma_dir); + if (dma_mapping_error(gpusvm->drm->dev, addr)) { + err = -EFAULT; + goto err_unmap; + } } svm_pages->dma_addr[j] = drm_pagemap_addr_encode @@ -1557,6 +1589,13 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm, flags.has_dma_mapping = true; } + if (dma_use_iova(state)) { + err = dma_iova_sync(gpusvm->drm->dev, state, 0, + svm_pages->state_offset); + if (err) + goto err_unmap; + } + if (pagemap) { flags.has_devmem_pages = true; drm_pagemap_get(dpagemap); diff --git a/include/drm/drm_gpusvm.h b/include/drm/drm_gpusvm.h index 2578ac92a8d4..cd94bb2ee6ee 100644 --- a/include/drm/drm_gpusvm.h +++ b/include/drm/drm_gpusvm.h @@ -6,6 +6,7 @@ #ifndef __DRM_GPUSVM_H__ #define __DRM_GPUSVM_H__ +#include <linux/dma-mapping.h> #include <linux/kref.h> #include <linux/interval_tree.h> #include <linux/mmu_notifier.h> @@ -136,6 +137,8 @@ struct drm_gpusvm_pages_flags { * @dma_addr: Device address array * @dpagemap: The struct drm_pagemap of the device pages we're dma-mapping. * Note this is assuming only one drm_pagemap per range is allowed. + * @state: DMA IOVA state for mapping. + * @state_offset: DMA IOVA offset for mapping. * @notifier_seq: Notifier sequence number of the range's pages * @flags: Flags for range * @flags.migrate_devmem: Flag indicating whether the range can be migrated to device memory @@ -147,6 +150,8 @@ struct drm_gpusvm_pages_flags { struct drm_gpusvm_pages { struct drm_pagemap_addr *dma_addr; struct drm_pagemap *dpagemap; + struct dma_iova_state state; + unsigned long state_offset; unsigned long notifier_seq; struct drm_gpusvm_pages_flags flags; }; -- 2.34.1
