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Date: Tue, 26 Jul 2022 14:12:09 +0100 From: Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com> To: Robert Beckett <bob.beckett@...labora.com>, Jani Nikula <jani.nikula@...ux.intel.com>, Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>, Rodrigo Vivi <rodrigo.vivi@...el.com>, David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch> Cc: kernel@...labora.com, Christoph Hellwig <hch@....de>, Thomas Hellstrom <thomas.hellstrom@...el.com>, Matthew Auld <matthew.auld@...el.com>, Tvrtko Ursulin <tvrtko.ursulin@...el.com>, intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH v4] drm/i915: stop using swiotlb On 25/07/2022 15:18, Robert Beckett wrote: > Calling swiotlb functions directly is nowadays considered harmful. See > https://lore.kernel.org/intel-gfx/20220711082614.GA29487@lst.de/ > > Replace swiotlb_max_segment() calls with dma_max_mapping_size(). > In i915_gem_object_get_pages_internal() no longer consider max_segment > only if CONFIG_SWIOTLB is enabled. There can be other (iommu related) > causes of specific max segment sizes. > > Cc: Christoph Hellwig <hch@....de> > Cc: Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com> > Cc: Thomas Hellstrom <thomas.hellstrom@...el.com> > Cc: Matthew Auld <matthew.auld@...el.com> > > v2: - restore UINT_MAX clamp in i915_sg_segment_size() > - drop PAGE_SIZE check as it will always be >= PAGE_SIZE > v3: - actually clamp to UINT_MAX in i915_sg_segment_size() > v4: - round down max segment size to PAGE_SIZE > > Reviewed-by: Christoph Hellwig <hch@....de> > Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@...el.com> > Signed-off-by: Robert Beckett <bob.beckett@...labora.com> > --- > drivers/gpu/drm/i915/gem/i915_gem_internal.c | 19 ++++--------------- > drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 2 +- > drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 4 ++-- > drivers/gpu/drm/i915/gem/i915_gem_userptr.c | 2 +- > drivers/gpu/drm/i915/i915_scatterlist.h | 17 ++++------------- > 5 files changed, 12 insertions(+), 32 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_internal.c b/drivers/gpu/drm/i915/gem/i915_gem_internal.c > index c698f95af15f..24f37658f1bb 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_internal.c > +++ b/drivers/gpu/drm/i915/gem/i915_gem_internal.c > @@ -6,7 +6,6 @@ > > #include <linux/scatterlist.h> > #include <linux/slab.h> > -#include <linux/swiotlb.h> > > #include "i915_drv.h" > #include "i915_gem.h" > @@ -38,22 +37,12 @@ static int i915_gem_object_get_pages_internal(struct drm_i915_gem_object *obj) > struct scatterlist *sg; > unsigned int sg_page_sizes; > unsigned int npages; > - int max_order; > + int max_order = MAX_ORDER; > + unsigned int max_segment; > gfp_t gfp; > > - max_order = MAX_ORDER; > -#ifdef CONFIG_SWIOTLB > - if (is_swiotlb_active(obj->base.dev->dev)) { > - unsigned int max_segment; > - > - max_segment = swiotlb_max_segment(); > - if (max_segment) { > - max_segment = max_t(unsigned int, max_segment, > - PAGE_SIZE) >> PAGE_SHIFT; > - max_order = min(max_order, ilog2(max_segment)); > - } > - } > -#endif > + max_segment = i915_sg_segment_size(i915->drm.dev) >> PAGE_SHIFT; > + max_order = min(max_order, ilog2(max_segment)); > > gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_RECLAIMABLE; > if (IS_I965GM(i915) || IS_I965G(i915)) { > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c > index 4eed3dd90ba8..34b9c76cd8e6 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c > +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c > @@ -194,7 +194,7 @@ static int shmem_get_pages(struct drm_i915_gem_object *obj) > struct intel_memory_region *mem = obj->mm.region; > struct address_space *mapping = obj->base.filp->f_mapping; > const unsigned long page_count = obj->base.size / PAGE_SIZE; > - unsigned int max_segment = i915_sg_segment_size(); > + unsigned int max_segment = i915_sg_segment_size(i915->drm.dev); > struct sg_table *st; > struct sgt_iter sgt_iter; > struct page *page; > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c > index 5a5cf332d8a5..7a828c9c0f6d 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c > +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c > @@ -189,7 +189,7 @@ static int i915_ttm_tt_shmem_populate(struct ttm_device *bdev, > struct drm_i915_private *i915 = container_of(bdev, typeof(*i915), bdev); > struct intel_memory_region *mr = i915->mm.regions[INTEL_MEMORY_SYSTEM]; > struct i915_ttm_tt *i915_tt = container_of(ttm, typeof(*i915_tt), ttm); > - const unsigned int max_segment = i915_sg_segment_size(); > + const unsigned int max_segment = i915_sg_segment_size(i915->drm.dev); > const size_t size = (size_t)ttm->num_pages << PAGE_SHIFT; > struct file *filp = i915_tt->filp; > struct sgt_iter sgt_iter; > @@ -568,7 +568,7 @@ static struct i915_refct_sgt *i915_ttm_tt_get_st(struct ttm_tt *ttm) > ret = sg_alloc_table_from_pages_segment(st, > ttm->pages, ttm->num_pages, > 0, (unsigned long)ttm->num_pages << PAGE_SHIFT, > - i915_sg_segment_size(), GFP_KERNEL); > + i915_sg_segment_size(i915_tt->dev), GFP_KERNEL); > if (ret) { > st->sgl = NULL; > return ERR_PTR(ret); > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c > index 094f06b4ce33..dfc35905dba2 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c > +++ b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c > @@ -129,7 +129,7 @@ static void i915_gem_object_userptr_drop_ref(struct drm_i915_gem_object *obj) > static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj) > { > const unsigned long num_pages = obj->base.size >> PAGE_SHIFT; > - unsigned int max_segment = i915_sg_segment_size(); > + unsigned int max_segment = i915_sg_segment_size(obj->base.dev->dev); > struct sg_table *st; > unsigned int sg_page_sizes; > struct page **pvec; > diff --git a/drivers/gpu/drm/i915/i915_scatterlist.h b/drivers/gpu/drm/i915/i915_scatterlist.h > index 9ddb3e743a3e..1377a97a20cf 100644 > --- a/drivers/gpu/drm/i915/i915_scatterlist.h > +++ b/drivers/gpu/drm/i915/i915_scatterlist.h > @@ -9,7 +9,7 @@ > > #include <linux/pfn.h> > #include <linux/scatterlist.h> > -#include <linux/swiotlb.h> > +#include <linux/dma-mapping.h> > > #include "i915_gem.h" > > @@ -127,19 +127,10 @@ static inline unsigned int i915_sg_dma_sizes(struct scatterlist *sg) > return page_sizes; > } > > -static inline unsigned int i915_sg_segment_size(void) > +static inline unsigned int i915_sg_segment_size(struct device *dev) > { > - unsigned int size = swiotlb_max_segment(); > - > - if (size == 0) > - size = UINT_MAX; > - > - size = rounddown(size, PAGE_SIZE); > - /* swiotlb_max_segment_size can return 1 byte when it means one page. */ > - if (size < PAGE_SIZE) > - size = PAGE_SIZE; > - > - return size; > + size_t max = min_t(size_t, UINT_MAX, dma_max_mapping_size(dev)); Hope your patience is not growing thin but blank line here as per checkpatch. I could fudge when applying though. Otherwise it finally passed CI, yay! Now do we dig deeper to a) understand how/where it failed and b) check what are the possible return values from dma_max_mapping_size(), or call it done? Regards, Tvrtko > + return round_down(max, PAGE_SIZE); > } > > bool i915_sg_trim(struct sg_table *orig_st);
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