From 172ae5b4c8c104af56804bf2406014849ed6fa37 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Mon, 5 Dec 2016 14:29:37 +0000 Subject: [PATCH] drm/i915: Fix i915_gem_evict_for_vma (soft-pinning) Soft-pinning depends upon being able to check for availabilty of an interval and evict overlapping object from a drm_mm range manager very quickly. Currently it uses a linear list, and so performance is dire and not suitable as a general replacement. Worse, the current code will oops if it tries to evict an active buffer. It also helps if the routine reports the correct error codes as expected by its callers and emits a tracepoint upon use. For posterity since the wrong patch was pushed (i.e. that missed these key points and had known bugs), this is the changelog that should have been on commit 506a8e87d8d2 ("drm/i915: Add soft-pinning API for execbuffer"): Userspace can pass in an offset that it presumes the object is located at. The kernel will then do its utmost to fit the object into that location. The assumption is that userspace is handling its own object locations (for example along with full-ppgtt) and that the kernel will rarely have to make space for the user's requests. This extends the DRM_IOCTL_I915_GEM_EXECBUFFER2 to do the following: * if the user supplies a virtual address via the execobject->offset *and* sets the EXEC_OBJECT_PINNED flag in execobject->flags, then that object is placed at that offset in the address space selected by the context specifier in execbuffer. * the location must be aligned to the GTT page size, 4096 bytes * as the object is placed exactly as specified, it may be used by this execbuffer call without relocations pointing to it It may fail to do so if: * EINVAL is returned if the object does not have a 4096 byte aligned address * the object conflicts with another pinned object (either pinned by hardware in that address space, e.g. scanouts in the aliasing ppgtt) or within the same batch. EBUSY is returned if the location is pinned by hardware EINVAL is returned if the location is already in use by the batch * EINVAL is returned if the object conflicts with its own alignment (as meets the hardware requirements) or if the placement of the object does not fit within the address space All other execbuffer errors apply. Presence of this execbuf extension may be queried by passing I915_PARAM_HAS_EXEC_SOFTPIN to DRM_IOCTL_I915_GETPARAM and checking for a reported value of 1 (or greater). v2: Combine the hole/adjusted-hole ENOSPC checks v3: More color, more splitting, more blurb. Fixes: 506a8e87d8d2 ("drm/i915: Add soft-pinning API for execbuffer") Signed-off-by: Chris Wilson Reviewed-by: Joonas Lahtinen Link: http://patchwork.freedesktop.org/patch/msgid/20161205142941.21965-2-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_drv.h | 3 +- drivers/gpu/drm/i915/i915_gem_evict.c | 106 ++++++++++++++++----- drivers/gpu/drm/i915/i915_gem_execbuffer.c | 1 + drivers/gpu/drm/i915/i915_trace.h | 28 ++++++ drivers/gpu/drm/i915/i915_vma.c | 2 +- 5 files changed, 112 insertions(+), 28 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index a0c67916ec20..605247baa7d1 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -3341,7 +3341,8 @@ int __must_check i915_gem_evict_something(struct i915_address_space *vm, unsigned cache_level, u64 start, u64 end, unsigned flags); -int __must_check i915_gem_evict_for_vma(struct i915_vma *target); +int __must_check i915_gem_evict_for_vma(struct i915_vma *vma, + unsigned int flags); int i915_gem_evict_vm(struct i915_address_space *vm, bool do_idle); /* belongs in i915_gem_gtt.h */ diff --git a/drivers/gpu/drm/i915/i915_gem_evict.c b/drivers/gpu/drm/i915/i915_gem_evict.c index 739ede7c89ed..fa40100146ea 100644 --- a/drivers/gpu/drm/i915/i915_gem_evict.c +++ b/drivers/gpu/drm/i915/i915_gem_evict.c @@ -212,45 +212,99 @@ found: return ret; } -int -i915_gem_evict_for_vma(struct i915_vma *target) +/** + * i915_gem_evict_for_vma - Evict vmas to make room for binding a new one + * @target: address space and range to evict for + * @flags: additional flags to control the eviction algorithm + * + * This function will try to evict vmas that overlap the target node. + * + * To clarify: This is for freeing up virtual address space, not for freeing + * memory in e.g. the shrinker. + */ +int i915_gem_evict_for_vma(struct i915_vma *target, unsigned int flags) { - struct drm_mm_node *node, *next; + LIST_HEAD(eviction_list); + struct drm_mm_node *node; + u64 start = target->node.start; + u64 end = start + target->node.size; + struct i915_vma *vma, *next; + bool check_color; + int ret = 0; lockdep_assert_held(&target->vm->i915->drm.struct_mutex); + trace_i915_gem_evict_vma(target, flags); - list_for_each_entry_safe(node, next, - &target->vm->mm.head_node.node_list, - node_list) { - struct i915_vma *vma; - int ret; + check_color = target->vm->mm.color_adjust; + if (check_color) { + /* Expand search to cover neighbouring guard pages (or lack!) */ + if (start > target->vm->start) + start -= 4096; + if (end < target->vm->start + target->vm->total) + end += 4096; + } - if (node->start + node->size <= target->node.start) - continue; - if (node->start >= target->node.start + target->node.size) + drm_mm_for_each_node_in_range(node, &target->vm->mm, start, end) { + /* If we find any non-objects (!vma), we cannot evict them */ + if (node->color == I915_COLOR_UNEVICTABLE) { + ret = -ENOSPC; break; + } vma = container_of(node, typeof(*vma), node); - if (i915_vma_is_pinned(vma)) { - if (!vma->exec_entry || i915_vma_pin_count(vma) > 1) - /* Object is pinned for some other use */ - return -EBUSY; - - /* We need to evict a buffer in the same batch */ - if (vma->exec_entry->flags & EXEC_OBJECT_PINNED) - /* Overlapping fixed objects in the same batch */ - return -EINVAL; - - return -ENOSPC; + /* If we are using coloring to insert guard pages between + * different cache domains within the address space, we have + * to check whether the objects on either side of our range + * abutt and conflict. If they are in conflict, then we evict + * those as well to make room for our guard pages. + */ + if (check_color) { + if (vma->node.start + vma->node.size == target->node.start) { + if (vma->node.color == target->node.color) + continue; + } + if (vma->node.start == target->node.start + target->node.size) { + if (vma->node.color == target->node.color) + continue; + } } - ret = i915_vma_unbind(vma); - if (ret) - return ret; + if (flags & PIN_NONBLOCK && + (i915_vma_is_pinned(vma) || i915_vma_is_active(vma))) { + ret = -ENOSPC; + break; + } + + /* Overlap of objects in the same batch? */ + if (i915_vma_is_pinned(vma)) { + ret = -ENOSPC; + if (vma->exec_entry && + vma->exec_entry->flags & EXEC_OBJECT_PINNED) + ret = -EINVAL; + break; + } + + /* Never show fear in the face of dragons! + * + * We cannot directly remove this node from within this + * iterator and as with i915_gem_evict_something() we employ + * the vma pin_count in order to prevent the action of + * unbinding one vma from freeing (by dropping its active + * reference) another in our eviction list. + */ + __i915_vma_pin(vma); + list_add(&vma->exec_list, &eviction_list); } - return 0; + list_for_each_entry_safe(vma, next, &eviction_list, exec_list) { + list_del_init(&vma->exec_list); + __i915_vma_unpin(vma); + if (ret == 0) + ret = i915_vma_unbind(vma); + } + + return ret; } /** diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c index 5f164adc837c..d665a33229bd 100644 --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c @@ -274,6 +274,7 @@ static void eb_destroy(struct eb_vmas *eb) exec_list); list_del_init(&vma->exec_list); i915_gem_execbuffer_unreserve_vma(vma); + vma->exec_entry = NULL; i915_vma_put(vma); } kfree(eb); diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h index 240067705e1c..18ae37c411fd 100644 --- a/drivers/gpu/drm/i915/i915_trace.h +++ b/drivers/gpu/drm/i915/i915_trace.h @@ -450,6 +450,34 @@ TRACE_EVENT(i915_gem_evict_vm, TP_printk("dev=%d, vm=%p", __entry->dev, __entry->vm) ); +TRACE_EVENT(i915_gem_evict_vma, + TP_PROTO(struct i915_vma *vma, unsigned int flags), + TP_ARGS(vma, flags), + + TP_STRUCT__entry( + __field(u32, dev) + __field(struct i915_address_space *, vm) + __field(u64, start) + __field(u64, size) + __field(unsigned long, color) + __field(unsigned int, flags) + ), + + TP_fast_assign( + __entry->dev = vma->vm->i915->drm.primary->index; + __entry->vm = vma->vm; + __entry->start = vma->node.start; + __entry->size = vma->node.size; + __entry->color = vma->node.color; + __entry->flags = flags; + ), + + TP_printk("dev=%d, vm=%p, start=%llx size=%llx, color=%lx, flags=%x", + __entry->dev, __entry->vm, + __entry->start, __entry->size, + __entry->color, __entry->flags) +); + TRACE_EVENT(i915_gem_ring_sync_to, TP_PROTO(struct drm_i915_gem_request *to, struct drm_i915_gem_request *from), diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c index 4c91a68ecb6d..bc077e51b3e7 100644 --- a/drivers/gpu/drm/i915/i915_vma.c +++ b/drivers/gpu/drm/i915/i915_vma.c @@ -401,7 +401,7 @@ i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags) vma->node.color = obj->cache_level; ret = drm_mm_reserve_node(&vma->vm->mm, &vma->node); if (ret) { - ret = i915_gem_evict_for_vma(vma); + ret = i915_gem_evict_for_vma(vma, flags); if (ret == 0) ret = drm_mm_reserve_node(&vma->vm->mm, &vma->node); if (ret)