Apply fix for "GPU HANG" issue

Relevant thread:
https://lore.kernel.org/xen-devel/Y06VthUrV6PjOcJH@mail-itl/T/#t

Fixes QubesOS/qubes-issues#7813

gpu-hang.patch

@@ -0,0 +1,163 @@
+From 26fe4749750f1bf843666ca777e297279994e33a Mon Sep 17 00:00:00 2001
+From: Robert Beckett <bob.beckett@collabora.com>
+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@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.
+
+Signed-off-by: Robert Beckett <bob.beckett@collabora.com>
+Signed-off-by: Christoph Hellwig <hch@lst.de>
+[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
+

kernel.spec.in

@@ -146,6 +146,7 @@ Patch12: 0013-xen-pcifront-pciback-Update-pciif.h-with-err-and-res.patch
 Patch16: 0001-usbip-tweak-clear-halt-with-simple-reset.patch
 Patch19: increase-reclaim-speed.patch
 Patch25: 0001-Re-enable-interrupts-before-loading-PNVM.patch
+Patch26: gpu-hang.patch
 
 %description
 Qubes Dom0 kernel.