From a575c6761757232ea2c7dc9f370640754b90cc69 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Mon, 28 Aug 2017 11:46:31 +0100 Subject: [PATCH] drm/i915: Recreate vmapping even when the object is pinned Sometimes we know we are the only user of the bo, but since we take a protective pin_pages early on, an attempt to change the vmap on the object is denied because it is busy. i915_gem_object_pin_map() cannot tell from our single pin_count if the operation is safe. Instead we must pass that information down from the caller in the manner of I915_MAP_OVERRIDE. This issue has existed from the introduction of the mapping, but was never noticed as the only place where this conflict might happen is for cached kernel buffers (such as allocated by i915_gem_batch_pool_get()). Until recently there was only a single user (the cmdparser) so no conflicts ever occurred. However, we now use it to allocate batches for different operations (using MAP_WC on !llc for writes) in addition to the existing shadow batch (using MAP_WB for reads). We could either keep both mappings cached, or use a different write mechanism if we detect a MAP_WB already exists (i.e. clflush afterwards), but as we haven't seen this issue in the wild (it requires hitting the GPU reloc path in addition to the cmdparser) for simplicity just allow the mappings to be recreated. v2: Include the i915_MAP_OVERRIDE bit in the enum so the compiler knows about all the valid values. Fixes: 7dd4f6729f92 ("drm/i915: Async GPU relocation processing") Testcase: igt/gem_lut_handle # byt, completely by accident Signed-off-by: Chris Wilson Cc: Joonas Lahtinen Link: https://patchwork.freedesktop.org/patch/msgid/20170828104631.8606-1-chris@chris-wilson.co.uk Reviewed-by: Joonas Lahtinen --- drivers/gpu/drm/i915/i915_cmd_parser.c | 2 +- drivers/gpu/drm/i915/i915_drv.h | 3 +++ drivers/gpu/drm/i915/i915_gem.c | 7 ++++++- drivers/gpu/drm/i915/i915_gem_execbuffer.c | 4 +++- 4 files changed, 13 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_cmd_parser.c b/drivers/gpu/drm/i915/i915_cmd_parser.c index f0cb22c..8ba932b 100644 --- a/drivers/gpu/drm/i915/i915_cmd_parser.c +++ b/drivers/gpu/drm/i915/i915_cmd_parser.c @@ -1073,7 +1073,7 @@ static u32 *copy_batch(struct drm_i915_gem_object *dst_obj, goto unpin_src; } - dst = i915_gem_object_pin_map(dst_obj, I915_MAP_WB); + dst = i915_gem_object_pin_map(dst_obj, I915_MAP_FORCE_WB); if (IS_ERR(dst)) goto unpin_dst; diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 8352cbe..0383e87 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -3485,6 +3485,9 @@ void __i915_gem_object_invalidate(struct drm_i915_gem_object *obj); enum i915_map_type { I915_MAP_WB = 0, I915_MAP_WC, +#define I915_MAP_OVERRIDE BIT(31) + I915_MAP_FORCE_WB = I915_MAP_WB | I915_MAP_OVERRIDE, + I915_MAP_FORCE_WC = I915_MAP_WC | I915_MAP_OVERRIDE, }; /** diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index ac02785..51a8dbb 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -2553,6 +2553,9 @@ static void *i915_gem_object_map(const struct drm_i915_gem_object *obj, GEM_BUG_ON(i != n_pages); switch (type) { + default: + MISSING_CASE(type); + /* fallthrough to use PAGE_KERNEL anyway */ case I915_MAP_WB: pgprot = PAGE_KERNEL; break; @@ -2583,7 +2586,9 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj, if (ret) return ERR_PTR(ret); - pinned = true; + pinned = !(type & I915_MAP_OVERRIDE); + type &= ~I915_MAP_OVERRIDE; + if (!atomic_inc_not_zero(&obj->mm.pages_pin_count)) { if (unlikely(IS_ERR_OR_NULL(obj->mm.pages))) { ret = ____i915_gem_object_get_pages(obj); diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c index 1c4fac0..dcce69a 100644 --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c @@ -1071,7 +1071,9 @@ static int __reloc_gpu_alloc(struct i915_execbuffer *eb, return PTR_ERR(obj); cmd = i915_gem_object_pin_map(obj, - cache->has_llc ? I915_MAP_WB : I915_MAP_WC); + cache->has_llc ? + I915_MAP_FORCE_WB : + I915_MAP_FORCE_WC); i915_gem_object_unpin_pages(obj); if (IS_ERR(cmd)) return PTR_ERR(cmd); -- 2.7.4