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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: i915 "GPU HANG", bisected to a2daa27c0c61 "swiotlb: simplify swiotlb_max_segment"
On Tue, Oct 18, 2022 at 05:52:16AM +0200, Marek Marczykowski-Górecki wrote: > not only) when using IGD in Xen PV dom0. After not very long time Xorg > crashes, and dmesg contain messages like this: > > i915 0000:00:02.0: [drm] GPU HANG: ecode 7:1:01fffbfe, in Xorg [5337] > i915 0000:00:02.0: [drm] Resetting rcs0 for stopped heartbeat on rcs0 > i915 0000:00:02.0: [drm] Xorg[5337] context reset due to GPU hang <snip> > I tried reverting just this commit on top of 6.0.x, but the context > changed significantly in subsequent commits, so after trying reverting > it together with 3 or 4 more commits I gave up. > > What may be an important detail, the system heavily uses cross-VM shared > memory (gntdev) to map window contents from VMs. This is Qubes OS, and > it uses Xen 4.14. Can you try the patch below? --- >From 26fe4749750f1bf843666ca777e297279994e33a Mon Sep 17 00:00:00 2001 From: Robert Beckett <bob.beckett@xxxxxxxxxxxxx> Date: Tue, 26 Jul 2022 16:39:35 +0100 Subject: drm/i915: stop abusing swiotlb_max_segment Calling swiotlb functions directly is nowadays considered harmful. See https://lore.kernel.org/intel-gfx/20220711082614.GA29487@xxxxxx/ 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. Signed-off-by: Robert Beckett <bob.beckett@xxxxxxxxxxxxx> Signed-off-by: Christoph Hellwig <hch@xxxxxx> [hch: added the Xen hack] --- 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 | 30 +++++++++++--------- 5 files changed, 25 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 c698f95af15fe..629acb403a2c9 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, get_order(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 f42ca1179f373..11125c32dd35d 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 e3fc38dd5db04..de5d0a7241027 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; @@ -538,7 +538,7 @@ 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 8423df021b713..e4515d6acd43c 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 9ddb3e743a3e5..c278888f71528 100644 --- a/drivers/gpu/drm/i915/i915_scatterlist.h +++ b/drivers/gpu/drm/i915/i915_scatterlist.h @@ -9,7 +9,8 @@ #include <linux/pfn.h> #include <linux/scatterlist.h> -#include <linux/swiotlb.h> +#include <linux/dma-mapping.h> +#include <xen/xen.h> #include "i915_gem.h" @@ -127,19 +128,22 @@ 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)); + + /* + * Xen on x86 can reshuffle pages under us. The DMA API takes + * care of that both in dma_alloc_* (by calling into the hypervisor + * to make the pages contigous) and in dma_map_* (by bounce buffering). + * But i915 abuses ignores the coherency aspects of the DMA API and + * thus can't cope with bounce buffering actually happening, so add + * a hack here to force small allocations and mapping when running on + * Xen. (good luck with TDX, btw --hch) + */ + if (IS_ENABLED(CONFIG_X86) && xen_domain()) + max = PAGE_SIZE; + return round_down(max, PAGE_SIZE); } bool i915_sg_trim(struct sg_table *orig_st); -- 2.30.2
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